US010294913B2

(12) United States Patent

Schurtenberger
(10) Patent No.: US 10 ,294,913 B2
(45) Date of Patent: May 21, 2019
(54 ) HYDROELECTRIC /HYDROKINETIC (56 ) References Cited
TURBINE AND METHODS FOR MAKING
AND USING SAME U . S . PATENT DOCUMENTS
(71) Applicant: Walter Schurtenberger , Key West, FL 1,713 ,446 A * 5/1929 Peterson ............ B63H 5 / 165
416 /247 R
(US ) 2 ,944 ,631 A * 7/ 1960 Kerry .................. B64D 33 /02
( 72 ) Inventor: Walter Schurtenberger , Key West, FL 55 / 306
(US ) (Continued )
(73) Assignee: HYDROKINETIC ENERGY CORP, FOREIGN PATENT DOCUMENTS
Key West, FL (US) DE 10036307 AL 2 /2002
( * ) Notice : Subject to any disclaimer , the term of this DE 10208588 AL 9 /2003
patent is extended or adjusted under 35 (Continued )
U .S .C . 154 (b ) by 0 days.
OTHER PUBLICATIONS
(21) Appl.No.: 15/697,401 ( 1 ) International Search Report, and ( 2 ) Written Opinion of the
( 22 ) Filed : Sep . 6, 2017 International Searching Authority (EPO ) in PCT Application No.
PCT/US2016 /017857 ,which is the parent application to the present
(65) Prior Publication Data application .
US 2018 /0087484 A1 Mar. 29, 2018 (Continued )
Related U .S . Application Data
(63) Continuation of application Primary Examiner — Jason D Shanske
No. Assistant Examiner — Brian O Peters
PCT/US2016 /017857, filed on Feb . 12 , 2016 .
(Continued ) (57 ) ABSTRACT
(51) Int . Cl. The application relates to unidirectional hydrokinetic tur
F03B 3 / 18 ( 2006 .01) bines having an improved flow acceleration system that uses
FO3B 3 /04 ( 2006 .01 ) asymmetrical hydrofoil shapes on some or all of the key
(Continued ) components of the turbine . These components that may be
(52 ) U .S . CI. hydrofoil shaped include , e .g ., the rotor blades ( 34 ), the
CPC ................ F03B 3 / 18 ( 2013 .01); FO3B 3/ 04 center hub ( 36 ), the rotor blade shroud (38 ), the accelerator
(2013.01 ); F03B 3 /121 (2013.01); F03B 3/ 126 shroud ( 20 ), annular diffuser (s) (40 ), the wildlife and debris
( 2013 .01); excluder ( 10 , 18 ) and the tail rudder (60 ) . The fabrication
(Continued ) method designs various components to cooperate in opti
(58 ) Field of Classification Search mizing the extraction of energy , while other components
CPC ...... FO3B 3 /04 ; FO3B 3 /06 ; FO3B 3 / 12 ; FO3B reduce or eliminate turbulence that could negatively affect
3 /121 ; F03B 3/ 126 ; Y10T 137 /794 ; Y10T other component( s ).
137 /8085 ; Y10T 137 /8122
(Continued ) 19 Claims, 24 Drawing Sheets

X28
 US 10 ,294 ,913 B2
Page 2
Related U .S . Application Data 6 ,872 ,232 B1 * 3 /2005 Pavlatos ........... .... B01D 45 / 12
55 / 306
(60 ) Provisional application No. 62 /115 ,540 , filed on Feb . 6 , 957 ,947
7 ,018 , 166
B2
B2
10 / 2005
3 /2006
Williams
Gaskell
12 , 2015 . 7 ,378 ,750 B2 5 / 2008 Williams
7 ,713 ,020 B2 5 /2010 Davidson
(51) FO3B
Int. Ci3./ 12 (2006 .01)
7 ,874 ,788 B2 * 1/ 2011 Stothers FO3B 3 / 04
415 / 148
F03B 11 /02 ( 2006 .01) 7,980,811 B2 * 7/ 2011 Presz, Jr . FO3D 1/ 04
F03B 17/06 (2006 .01) 415 /4 .3
(52 ) U . S . CI. 8 ,021 , 100 B2 9 / 2011 Presz , Jr.
CPC . ............ FO3B 11 /02 (2013 .01) ; F03B 17 /061 8 , 308 ,422 B2 11 /2012 Williams
8 ,466 ,595 B2 * 6 / 2013 Spooner ................ FO3B 13 /083
( 2013.01) ; F05B 2220 /7068 (2013 .01) ; F05B 290 /54
2230 /6102 (2013.01); F05B 2230 /80 8 ,622 ,688 B2 1/ 2014 Presz , Jr.
( 2013 .01 ); F05B 2240 / 124 (2013 .01); F05B 8 ,714 ,923 B2 * 5/ 2014 PreszSZ , Jr. ............. FO1D 25 / 24
2240 /13 ( 2013 .01 ); F05B 2240 /33 (2013 .01 ); 415 /220
F05B 2240 / 911 (2013 .01 ); F05B 2240 / 93 9 ,000 ,604 B2 * 4 /2015 Sireli .......... FO3B 11 /02
(2013 . 01 ); F05B 2240 / 97 (2013 .01); F05B 290 / 54
2002/0088222 AL 7 /2002 Vauthier
2250 /232 (2013. 01); F05B 2250 /73 ( 2013 .01) ; 2003/0193198 A1 10 /2003 Wobben
F05B 2260 /84 (2013 . 01 ); YO2E 10 / 28 2005/ 0031442 A1 2/2005 Williams
(2013 .01); YO2E 10 /38 (2013 .01 ); YO2P 2005 /0285407 A1 * 12 /2005 Davis ........ FO3B 3 / 128
290 / 54
70 /527 (2015. 11) 2010 /0007148 A1 1/ 2010 Davis
(58 ) Field of Classification Search 2010 /0025998 AL 2 /2010 Williams
USPC . .. . .. . . .. . ............... 416 /223 R 2012 /0187693 A1* 7 /2012 Houvener FO3B 17/ 061
See application file for complete search history. 2013/0266446 Al 10 / 2013 Presz , Jr.
290 / 54

(56) References Cited 2013 /0287496 Al 10 / 2013 Ayre

2014 /0369841 A1 * 12 /2014 Duchene .............. FO3B 13 /264
U .S . PATENT DOCUMENTS 416 / 223 A
3,980,894 A * 9/1976 Vary ................. FO3B 13 / 105 FOREIGN PATENT DOCUMENTS
290 /54
3,986 ,787 A * 10 / 1976 Mouton , Jr. .......... FO3B 11/02 DE 102010046901 Al 3/ 2012
290/ 54 DE 102014119253 A1 6 /2016
4 ,075, 500 A 2/ 1978 Oman EP 2620635 * 7 /2013
4 , 163, 904 A 8 / 1979 Skendrovic GB 2408294 A 5 / 2005
4 ,219 , 303 A 8 / 1980 Mouton , Jr. WO 2007107505 AL 9 /2007
4 , 221 ,538 A 9 / 1980 Wells WO 2014194348 A1 12 /2014
4 , 313 ,711 A 2 / 1982 Lee WO 2015000964 AL 1 /2015
4 ,421,990 A 12 / 1983 Heuss WO 2016185101 A1 11 /2016
5, 226 ,804 A * 7 / 1993 Do . .. . .. FO3B 3 / 121
416 /223 R OTHER PUBLICATIONS
6 ,053,700 A * 4/ 2000 Fosdick .............. B63J 3 /04
416 / 124 Gouhier, “ SeaUrchin : the future is tidal,” Materials Today, Feb . 19 ,
6 ,086 ,330 A * 7/2000 Press .................... F04D 29 / 384 2013 (Country Unknown ) (Accessed on Internet at: https://www .
415 / 119 materialstoday.com /composite -applications/ features/seaurchin -the
6 , 138 ,950 A * 10 / 2000 Wainfan ............ B64D 33 /02
244 / 53 B future -is -tidal ) .
6 , 168, 373 B1 1/ 2001 Vauthier Search Report dated Jan . 23 , 2019 , in counterpart Chinese patent
6 ,406 ,251 B1 6 / 2002 Vauthier application .
RE38, 336 E 12 / 2003 Williams
6 ,729, 840 B2 5 / 2004 Williams * cited by examiner
U . S . Patent May 21, 2019 Sheet 1 of 24 US 10 ,294,913 B2

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atent May 21 , 2019 Sheet 3 of 24 US 10 ,294 , 913 B2

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U . S . Patent May 21, 2019 Sheet 4 of 24 US 10 ,294,913 B2

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U . S . Patent May 21 , 2019 Sheet 8 of 24 US 10 ,294, 913 B2

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U . S . Patent May 21, 2019 Sheet 9 of 24 US 10 ,294, 913 B2

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U . S . Patent May 21 , 2019 Sheet 10 of 24 US 10, 294 ,913 B2

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U . S . Patent May 21 , 2019 Sheet 11 of 24 US 10 ,294,913 B2

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U . S . Patent May 21, 2019 Sheet 12 of 24 US 10 ,294,913 B2

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U . S . Patent May 21 , 2019 Sheet 13 of 24 US 10 ,294 ,913 B2

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U .S . Patent May 21,2019 Sheet 14 of 24 US 10 ,294 , 913 B2

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U . S . Patent May 21, 2019 Sheet 18 of 24 US 10, 294 ,913 B2

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U . S . Patent May 21, 2019 Sheet 19 of 24 US 10,294,913 B2
6kn Profile

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atent May 21 , 2019 Sheet 20 of 24 US 10, 294 ,913 B2

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 atent May 21 , 2019 Sheet 21 of 24 US 10 ,294 ,913 B2

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FIG . 35
Tide Turbine Power, Inside Diameter 1.5m
500 ,000
450,000 With Nozzle with
Accelerator
400 ,000 - No Nozzle
350,000 without Accelerator
300,000
Watts250,000
,
Power
200,000
150,000
100,000
50,000 -
1 2 3 4 5 6 7
Water Velocity ,Knots
FIG . 36
U . S . Patent May 21, 2019 Sheet 22 of 24 US 10, 294 ,913 B2

High Velocity Zone

* Y

Inside Turbine Velocity :Magnitude (m /s)

0.00000 5.6309 11.262 16.893 22.523 28.154
FIG . 37A

- High Pressure Zone

Inside Turbine

Low Pressure Zone

Inside Turbine

Absolute Pressure (Pa)

81780 . 95424 . 1.0907e + 05 1.2271e + 05 1.3636e + 05 1.5000e + 05
FIG . 37B
 atent May 21 , 2019 Sheet 23 of 24 US 10 ,294 ,913 B2

High Velocity Zone

Inside Turbine

Velocity (m /s)
0. 17804 3.8938 7.6095 11.325 15 .041 18.757

FIG . 38A

High Pressure Low Pressure Zone

Zone Inside Inside Turbine
Turbine
Velocity: Magnitude (m /s )
0.17804 3.8938 7.6095 11.325
YX
15 .041 18 .757
FIG . 38B
U . S . Patent May 21 , 2019 Sheet 24 of 24 US 10, 294 ,913 B2

-High Pressure Zone

on the Top Side of
Hydrofoil (Extrados )

Absolute Pressure (Pa)

-3.9254e +05 -2.6362e+05-1.3471e +05 -5793.3 1.2312ematerinarinnar+05eren 2.5204e +05
FIG . 39

-Low Pressure Zone

on the Top Side of
Hydrofoil(Intrados)

Absolute Pressure (Pa)

-3.9254e +05 -2.6362e+05-1.3471e +05 -5793.3 1.2312e +05 2.5204e+05
FIG . 40
 US 10 , 294 ,913 B2
HYDROELECTRIC /HYDROKINETIC and cost advantages to be gained by replacing conventional
TURBINE AND METHODS FOR MAKING coal- fired power plants with hydroelectric installations.
AND USING SAME Older installations of hydroelectric power plants are mostly
situated inside dams or below dams using the pressure at the
BACKGROUND OF THE INVENTION 5 bottom of the dam to operate a water turbine that drives
electric generators .
The present invention relates to hydrokinetic turbines Since World War I the field of science, today called fluid
designed for the purpose of generating electricity , and to dynamics , has developed tremendously and become a very
methods for designing and using such turbines. It further precise and finite science which is used today in the design
relates to certain elements employed in hydrokinetic tur- 10 of modern hydrofoils. Hydrofoils ( as well as airfoils , also
bines . The turbines according to the invention are intended part of fluid dynamics ) are used for a large variety of
to be placed underwater, in a fixed , floating, anchored or purposes , including most designs in aeronautics , in motor
towed configuration , in any location where the effective vehicles, in watercraft, and in isolated elements employed in
water current preferably flows with a minimum speed of hydrokinetic turbines.
about 0 . 25 m / s. The water flow or current may be of any type 15 Hydrokinetic turbines can be divided up into different
or source , although typically it is comprised of one or more categories or types . For example , a turbine can either be
of the following types of water flow or current: bi-directional or unidirectional. In the former case , the
a ) Fixed , floating or anchored in continuous water flow or turbine in defined such that it can be operated by a current
current, as found , e . g ., in ocean currents , rivers or that flows in both axial directions through the turbine, e . g .,
streams. 20 to be actuated to generate power both by an incoming tidal
b ) Fixed , floating or anchored in fluctuating, alternating flow as well as by a receding tidal flow . On the other hand ,
and /or cyclical water flow or currents thatmay change a unidirectional turbine is driven only by the flow of water
direction periodically or irregularly , as found, e .g ., in in a single axial direction . From a hydrodynamic standpoint,
tidal flow or seasonal flow . the design criteria to produce a bi-directional turbine are
c ) Fixed , floating or anchored in mechanically or naturally 25 significantly more limited than in the case of a unidirectional
induced occurring currents that are created by , e. g., turbine , i.e., all design criteria that would produce an
filling and emptying of reservoirs, lakes, dams or locks. adverse effect upon reversal of fluid flow direction .
d ) The device may be towed through the water by a vessel Another way of categorizinghydrokinetic turbines resides
or other device or method to artificially or effectively in their hub design , namely , whether the center hub is either
create a flow through the device . 30 closed or open . Traditionally , most hydrokinetic turbines
The power of flowing water has been used by mankind for possess a non -rotating ( fixed with respect to the turbine
millennia to generate energy of various kinds for many outer shroud ) center hub that is closed or solid , and about
different purposes . It has been used for milling grain , belt which the rotor blades rotate . See, e . g ., the following docu
driven applications to run machines in factories and to ments for examples : U . S . Pat. No. 3 , 986 , 787 to Mouton et
power many kinds of devices mechanically. For the last 150 35 al., U .S . Pat. No. 4 ,221 ,538 to Wells, U . S . Pat . No. 4 ,313, 711
years water flow has proven to be very efficient for electrical to Lee, U .S . Pat. No. 4,421, 990 to Heuss et al., U .S . Pat. No .
generation in countless different designs and applications. 6 , 168,373 to Vauthier, U .S . Pat. No. 6 ,406 ,251 to Vauthier
The basic principle of using permanent magnets and and GB 2 , 408 ,294 to Susman et al. Some designs have a
copper coils to generate electricity is still being used today solid center hub , but rotate about bearingsbetween a radially
in many different forms, including using flowing water and 40 outer rotor ring and a turbine shroud , as disclosed , e . g ., in
water turbines to drive electrical generators and alternators . U .S . Pat. No. 4 , 163 , 904 to Skendrovic .
Most ocean currents are caused by wind , which in turn is More recently , one company has pursued hydrodynamic
caused by the Coriolis forces coming from the rotation of the turbine designs in which there is provided an open center
earth . These currents are often influenced by the position of hub, for environmental reasons, i.e., to provide a safe
landmasses that can divert the flow and in some cases 45 passageway for sea creatures . See , e . g ., the following docu
accelerate the flow . Ocean currents can also be caused by ments for examples: U . S . Pat. Nos. 6 , 957, 947 , 7 , 378 , 750 ,
density differences in water masses , temperature differences 8 , 308,422 and 8 , 466 ,595 . In these basically hubless designs ,
or variations in the salinity of the water. The ocean currents the rotor blades are typically mounted at the radial inside
on this planet are probably the biggest untapped source of upon an inner ring member, and on the radial outside on an
energy in existence . River currents are also often used as a 50 outer ring member, and in some designs, there is no inside
very good and efficient source of energy . ring member present at all. These basically hubless turbine
Since the beginning of technological development, there designs are all bi-directional and are axially symmetrical in
have been many different attempts made to harvest this design .
energy with varying degrees of success and efficiency. The I n an adaptation of the open center concept, a type of
currents that are most accessible and easiest to use for 55 hydrokinetic turbine is disclosed that is of the fixed center
energy generation are near -shore surface currents of the hub design noted above, but also includes a passageway or
ocean and river currents . Water flow can also be produced an opening in the center hub. See , e. g ., US 2013 /00443685
artificially by building dams and creating reservoirs to to Sireli et al., U . S . Pat. No . 7 ,471,009 to Davis et al., both
accumulate large masses of water that can be utilized on of which relate to a unidirectional turbine design . Also see ,
demand . 60 U .S . Pat. No. 7 , 874 , 788 to Stothers et al., and US 2010 /
In 1882 the world 's first hydroelectric power plant was on 0007148 to Davis et al., which relate to specially -config
the Fox River in Appleton Wis . By 1889, 200 electrical ured , bi-directional hydrokinetic turbines that include the
plants were built in the USA , and by 1920 , hydropower was optional use of an open center hub or, in the latter, a bypass
used for 25 % of US electrical generation , which usage by opening in the hub , as in related Davis et al. ' 009 , noted
1940 went up to 40 % . Today only 6 to 8 % of the electricity 65 above (see FIG . 7 of both ).
produced in the United States comes from hydropower . Hydrokinetic power generation remains of great interest
There are vast opportunities and significant environmental and has gained growing importance along with solar power
 US 10 ,294 ,913 B2
and wind power. There is a need for significant effort to be ing a water entrance end and a water exit end defining a
made to design and build much more sophisticated and direction of water flow through the turbine, comprising a
highly efficient hydrokinetic power - generating turbines ; generally cylindrical accelerator shroud that has a wall
however , because the process of refining turbine designs is cross -section that comprises an asymmetrical hydrofoil
in many respects unpredictable and therefore time-consum - 5 shape , wherein the hydrofoil shape comprises a generally
ing , there has unfortunately been a tendency to simply build S - shaped profile in which the outer surface comprises a
larger versions of existing turbine designs in order to gain forward convex portion and a rearward concave portion that
larger energy output from them . New , highly efficient tur transitions into the forward convex portion , and the inner
bines will enable the extraction of increased amounts of surface comprises a rearward convex portion and a forward
energy from a renewable source , with practically no envi- 10 portion that has a shape that is either straight or concave and
ronmental impact. Further improvements in such turbines transitions into the rearward convex portion ; and a rotor
are highly desired , for these reasons. assembly that is mounted for rotation within the accelerator
shroud around an axis that is generally parallel to the
SUMMARY OF THE INVENTION direction of water flow through the turbine , the rotor assem
15 bly comprising a plurality of rotor blades extending radially
According to one aspect of the present invention, there is outwardly from the center of the turbine and being mounted
provided a unidirectional hydrokinetic turbine having a for rotation within the accelerator shroud . Preferably , the
water entrance end and a water exit end defining a direction rotor assembly further comprises a center hub member,
of water flow through the turbine , comprising a generally preferably with a generally round profile member having a
cylindrical accelerator shroud that has a wall cross -section 20 hydrofoil profile , and the rotor blades are attached to the hub
that defines within its cylindrical cross -section a water flow member. More preferably , the hub member comprises a
area that contains structure located therein that consists generally round profile member having an open center , with
essentially of an integral hydrokinetic force -generating the wall members surrounding the open center forming an
member comprising a center hub member having an asym - asymmetric hydrofoil profile , with the extrados being
metrical hydrofoil profile ; and a plurality of blade members 25 toward the outside of the turbine and the intrados facing
mounted on the hub member, wherein the force - generating toward the center of the hub .
member is mounted for rotation on the inner surface of the In some preferred embodiments, the rotor member further
accelerator shroud. Preferably, the hydrokinetic force - gen - comprises a rotor outer ring to which the blade tips are
erating member comprises a rotor assembly that further attached and which has an outer circumference configured
includes a rotor outer ring to which the blade tips are 30 for rotation within the accelerator shroud . In other preferred
attached and which has an outer circumference that is embodiments , the unidirectional hydrokinetic turbine fur
configured for rotation within the accelerator shroud. Pref- ther comprises an annular diffuser comprising, a generally
erably , the hub member comprises a generally round profile cylindrical ring member that has a wall cross - section that
member having an open center and wherein the wall mem - also comprises an asymmetrical hydrofoil shape, the annular
bers surrounding the open center form an asymmetric hydro - 35 diffuser having a diameter greater than the diameter of the
foil profile , with the extrados being toward the outside of the accelerator shroud and being positioned behind the main
turbine and the intrados facing toward the center of the hub . accelerator shroud , in the direction ofwater flow through the
Also , the blades preferably have an asymmetrical hydrofoil - turbine , preferably in overlapping relationship .
shaped cross - sectional configuration , with the blades most According to another aspect of the present invention ,
preferably having a chord length at their radially outer ends 40 there is provided a unidirectional hydrokinetic turbine hav
that is greater than the chord length at their radially inner ing a water entrance end and a water exit end defining a
ends , and a profile /chord thickness at their radially outer direction of water flow through the turbine , comprising a
ends that is greater than the profile thickness at their radially generally cylindrical accelerator shroud that has a wall
inner ends. It is most preferred that accelerator shroud has a cross -section that comprises an asymmetrical hydrofoil
wall cross - section that is also an asymmetrical shape . 45 shape and defines within its cylindrical cross - section a flow
According to other preferred embodiments , the unidirec - area , where the hydrofoil shape serves to accelerate the flow
tional hydrokinetic turbine has a center hub having a length of water through the accelerator shroud and to create a
that extends both forwardly and rearwardly a substantial negative pressure field behind the accelerator shroud , in the
distance past the edges of the blades , and more preferably direction of water flow ; a rotor assembly that is mounted for
extending from the blades forwardly to a first point that is 50 rotation within the accelerator shroud around an axis that is
rearward of the water entrance end of the accelerator shroud , generally parallel to the direction of water flow through the
and extending rearwardly to a point at least as far as the turbine, the rotor assembly comprising a generally elongated
water exit end of the accelerator shroud . Preferably , the cylindrical center hub having and a wall cross - section com
center hub extends a total distance from about 50 to 80 % , prising a hydrofoil shape; a plurality of rotor blades fixed to
more preferably from about 60 to 70 % and most preferably 55 and extending radially outwardly from the center hub wall
about 2/3 of the length of the accelerator shroud . for rotation therewith and terminating at rotor blade tips,
According to other preferred embodiments, the unidirec - which blades have an asymmetrical hydrofoil -shaped cross
tional hydrokinetic turbine further comprises an annular sectional configuration ; and a rotor outer ring to which the
diffuser comprising a generally cylindrical ring member that blade tips are attached and having an outer circumference
has a wall cross - section , also preferably comprising an 60 which is configured for rotation within the accelerator
asymmetrical hydrofoil shape , the annular diffuser having a shroud : and an annular diffuser comprising, a generally
diameter greater than the diameter of the accelerator shroud cylindrical ring member that has a wall cross - section com
and being positioned behind the main accelerator shroud , in prising an asymmetrical hydrofoil shape. The annular dif
the direction of water flow through the turbine, preferably in fuser has a diameter greater than the diameter of the accel
an overlapping relationship . 65 erator shroud and is positioned behind the main accelerator
According to another aspect of the present invention , shroud, in the direction of water flow through the turbine,
there is provided a unidirectional hydrokinetic turbine hav preferably in overlapping relationship , whereby the hydro
 US 10 ,294 ,913 B2
foil shape of the annular diffuser serves to accelerate the flow , and that defines within its cylindrical cross -section a
flow of water through the annular diffuser and to create a water flow area that contains an integral hydrokinetic force
negative pressure field behind the annular diffuser, and in generating member comprising a center hub member having
cooperation with the hydrofoil shape of the accelerator an asymmetrical hydrofoil profile , and a plurality of blade
shroud , the hydrofoil shaped rotor hub and the blades , to 5 members mounted on the hub member, wherein the force
augment acceleration of water flow through the accelerator generating member is mounted for rotation on the inner
shroud at the location of the rotor assembly. surface of the accelerator shroud . The turbine is character
In some preferred embodiments of the unidirectional ized by its ability to accelerate the ambient flow velocity of
hydrokinetic turbine, the blades have a chord length at their the water entering the turbine to a flow velocity at the blade
radially outer ends that is greater than the chord length at 10 members that is at least about twice the ambient flow
their radially inner ends and /or the blades have a profile / velocity, preferably at least about 21/2 times and most
chord thickness at their radially outer ends that is greater preferably at least about 3 times . Furthermore, the turbine is
than the profile / chord thickness at their radially inner ends . characterized by its ability to provide an increase in power
In other preferred embodiments , the center hub comprises a output, compared to conventional hydrokinetic turbines of
generally round profile member having an open center, 15 equal diameter, by a factor of at least about 25 % , preferably
wherein the wallmembers surrounding the open center form by at least about 50 % and most preferably by at least about
a asymmetric hydrofoil profile, with the extrados being 80 % .
toward the outside of the turbine and the intrados facing According to still another aspect of the present invention ,
toward the center of the hub . Preferably, the center hub has there is provided a shroud that is designed for use in a
a length that extends both forwardly and rearwardly a 20 unidirectional hydrokinetic turbine having a water entrance
substantial distance past the edges of the blades , more end and a water exit end defining a direction of water flow
preferably the center hub extends from the blades forwardly through the turbine . The accelerator shroud comprises a
to a first point that is rearward of the water entrance end of generally cylindrical accelerator shroud that has a wall
the accelerator shroud , and extends rearwardly to a point at cross -section comprising a generally asymmetrical hydrofoil
least as far as the water exit end of the accelerator shroud . 25 shape, wherein the hydrofoil shape comprises a generally
Preferably , the center hub extends a total distance from S - shaped profile in which the outer surface comprises a
about 50 to 80 % , more preferably from about 60 to 70 % and forward convex portion and a rearward concave portion , and
most preferably about 2/3 of the length of the accelerator the inner surface comprises a rearward convex portion and
shroud . It may also extend rearwardly beyond the rear edge a forward portion that has a shape that is either straight or
of the accelerator shroud . 30 concave. This unique configuration serves to accelerate in an
According to still another aspect of the present invention , optimum manner the flow of water through themain accel
there is provided a unidirectional hydrokinetic turbine hav - erator shroud and to create a negative pressure field behind
ing a water entrance end and a water exit end defining a the accelerator shroud , in the direction of water flow .
direction of water flow through the turbine, comprising a According to yet another aspect of the present invention ,
generally cylindrical accelerator shroud section that defines 35 there is provided a unidirectional hydrokinetic turbine hav
within its cylindrical cross -section a water flow area ; a rotor ing a water entrance end and a water exit end defining a
assembly that is mounted for rotation within the accelerator direction of water flow through the turbine , comprising a
shroud around an axis that is generally parallel to the generally cylindrical accelerator shroud that has a wall
direction of water flow through the turbine, the rotor assem - cross -section that comprises an asymmetrical hydrofoil
bly comprising a plurality of rotor blades extending radially 40 shape ; and a rotor assembly that is mounted for rotation
outwardly from the center of the turbine and a wildlife within the accelerator shroud around an axis that is generally
and / or debris deflector member mounted at the water parallel to the direction of water flow through the turbine ,
entrance end of the accelerator shroud , the deflector com - the rotor assembly comprising a plurality of rotor blades
prising a generally conically -shaped structure which is extending radially outwardly from the center of the turbine
tapered toward its forward /narrow end and comprises an 45 and a rotor outer ring to which the blade tips are attached for
array of deflector rods that run parallel to each other and are rotation within the accelerator shroud , wherein the blades
spaced essentially evenly at a pre - determined distance over have an asymmetrical hydrofoil- shaped cross -sectional con
their full - length with respect to one another, whereby the figuration , with the blades most having either a chord length
predetermined distance defines the maximum size of wild at their radially outer ends that is greater than the chord
life or an object that can pass through the deflector. Prefer - 50 length at their radially inner ends , and / or a profile /chord
ably , the wildlife and /or debris deflector member includes at thickness at their radially outer ends that is greater than the
its forward / narrow end a ring member to which the deflector profile thickness at their radially inner ends.
rods are attached , the ring having a diameter no larger than Preferably , the rotor assembly further comprises a center
the pre -determined distance of the deflector rods. In other hub member, preferably with a generally round profile
preferred embodiments, the ring member and / or at least 55 member having an asymmetrical hydrofoil profile , and the
some and preferably all of the deflector rods have a hydro rotor blades are attached to the hub member. More prefer
foil -shaped cross -section in order to reduce turbulence in the ably, the hub member comprises a generally round profile
water flowing across the ring and / or deflector rods. member having an open center , with the wall members
According to another aspect of the present invention , surrounding the open center forming an asymmetric hydro
there is provided a unidirectional hydrokinetic turbine hav - 60 foil profile , with the extradosbeing toward the outside of the
ing a water entrance end and a water exit end defining a turbine and the intrados facing toward the center of the hub .
direction of water flow through the turbine, comprising a According to still another aspect of the present invention ,
generally cylindrical accelerator shroud that has a wall there is provided a wildlife and /or debris deflector member
cross - section comprising a generally asymmetrical hydrofoil that is designed for use in a hydrokinetic turbine. The
shape, which serves to accelerate the flow of water through 65 wildlife and / or debris deflector member is designed to be
the main accelerator shroud and to create a negative pressure mounted at either end or both ends of a turbine. The deflector
field behind the accelerator shroud , in the direction of water comprises a generally conically -shaped structure which is
 US 10 ,294 ,913 B2
tapered toward one end and comprises an array of deflector disclosure of certain preferred embodiments of the invention
rods that run parallel to each other and are spaced essentially set forth herein and not for the purpose of limiting the same.
evenly at a pre - determined distance over their full-length FIG . 1 is a three - dimensional front view of one embodi
with respect to one another, whereby the predetermined ment of a hydrokinetic turbine with support/mounting struc
distance defines the maximum size of wildlife or an object 5
that can pass through the deflector. Preferably , the wildlife FIG . 2 is a three -dimensional rear view of the hydroki
and / or debris deflector member includes at its narrower end
a first ring member to which the deflector rods are attached , netic turbine of FIG . 1, with support/mounting structure;
the first ring having a diameter no larger than the pre FIG . 3 is a cross -sectional side view of the hydrokinetic
determined distance . Similarly , the deflector preferably has 10 turbine of FIG . 1 , with support/mounting structure ;
at or near its wider end a second ring member to which the FIG . 4 is a three - dimensional view of one embodiment of
deflector rods are attached . In other preferred embodiments, an accelerator shroud with annular diffuser ;
at least some and preferably all of the deflector rods and/or FIG . 5A is a partial cross -sectional view of an S - shaped /
rings have a hydrofoil-shaped cross -section . double -curved hydrofoil accelerator shroud , in an arrange
In accordance with another aspect of the present inven
tion , there is provided a method for designing a unidirec - 15sment as shown in FIG . 4 , with annular diffuser ;
FIG . 5B is a partial cross -sectional view of a non - S
tional hydrokinetic turbine having a water entrance end and
a water exit end defining a direction of water flow through shaped hydrofoil accelerator shroud, in an arrangement as
the turbine , comprising designing a generally cylindrical shown in FIG . 4 , with annular diffuser;
accelerator shroud that has a wall cross -section that com FIG . 6 is a partial cross -sectional view of another embodi
prises an initial asymmetrical hydrofoil shape and defines 20 ment of an accelerator shroud, with multiple annular diffus
within its cylindrical cross -section a flow area , where the ers of similar diameters;
hydrofoil shape is selected based on fluid dynamics prin - FIG . 7 is a partial cross- sectional view of another embodi
ciples to serve to accelerate the flow of water through the ment of an accelerator shroud , with multiple annular diffus
accelerator shroud and to create a negative pressure field ers with different diameters :
behind the accelerator shroud , in the direction of water flow ; 25 FIG . 8 is a three- dimensional view of one embodiment of
designing a rotor assembly that is mounted for rotation an entire turbine with central rotor section ;
within the accelerator shroud around an axis that is generally FIG . 9 is a cross -sectional view the entire turbine of FIG .
parallel to the direction of water flow through the turbine, 8 , with central rotor section in place ;
the rotor assembly comprising (i) a generally elongated FIG . 9A is an isolated perspective view of the accelerator
cylindrical center hub having and a wall cross-section com
prising an initial hydrofoil shape that is selected based on 30 shroud , schematically showing the placement of coils
FIG . 10 is a three- dimensional view of the rotor section
fluid dynamics principles ; ( ii ) a plurality of rotor blades
fixed to and extending radially outwardly from the center alone of the embodiment of FIG . 8 ;
hub wall for rotation therewith and terminating at rotor tips, FIG . 11 is a schematic side view of the rotor section of
which blades have an initial asymmetrical hydrofoil -shaped FIG . 8 , showing one of the hydrofoil shaped rotorblades, the
cross -sectional configuration that is selected based on fluid 35 rotor blade shroud and the hydrofoil shaped center hub ;
dynamics principles ; and ( iii ) a rotor outer ring to which the FIG . 12 is a perspective view of four rotor blades alone in
blade tips are attached and having an outer circumference the embodiment of FIG . 8 ;
which is configured for rotation within the accelerator FIG . 12A is an isolate perspective view of a single
shroud ; designing an annular diffuser comprising a generally exemplary rotor blade ;
cylindrical ring member that has a wall cross -section com - 40 FIG . 13 is a cross - sectional view of one embodiment of a
prising an initial asymmetrical hydrofoil shape that is rotor blade , illustrating certain preferred features , including
selected based on fluid dynamics principles, wherein the the variable angle of attack , variable chord length , and
annular diffuser has a diameter greater than the diameter of variable thickness of profile and twist;
the accelerator shroud and is positioned behind the main All FIG . 14 is an isolated perspective view of a four rotor
accelerator shroud , in the direction of water flow through the 45 blade embodiment, with cross - sections of hydrofoil shapes
turbine, preferably in overlapping relationship , and modify
ing the initial hydrofoil shapes of the annular accelerator, the ofFIG
the blades ;
. 15 is a perspective view of single rotor blade alone
center hub, the rotor blades and the annular diffuser, in with cross - sections of hydrofoil shapes;
response to CFD testing /analysis of a turbine design com FIG . 16 is a perspective view of one embodiment of a
prising such components , in such a way as to provide final 50 turbine with front and rear wildlife and debris excluders ;
hydrofoil shapes for all of these components that (a ) at least
enhance, and preferably optimize the ability to accelerate the withFIGfront
. 17 is a cross -sectional view of the turbine of FIG . 16 ,
and rear wildlife and debris excluders ;
flow of water through the annular diffuser and to create a
negative pressure field behind the annular diffuser and (b ) FIG . 18 is a perspective view of the turbine of FIG . 16 ,
provide cooperation with the final hydrofoil shapes of the with front and rear wildlife and debris excluders and utiliz
accelerator shroud , the rotor hub and the blades , to at least 55 ing a hydrofoil/ teardrop shaped deflector bar to form the
enhance , and preferably optimize acceleration of water flow excluders ;
through the accelerator shroud at the location of the rotor FIG . 18A is an isolated perspective view showing in detail
assembly . the teardrop profile of FIG . 18 ;
Further features and advantages of the present invention FIG . 19 is an exploded perspective view schematically
will become apparent from the detailed description of pre - 60 showing all components in partial cross -section according to
ferred embodiments that follows, when considered together one embodiment of the invention ;
with the accompanying figures of drawing. FIG . 20 is an exploded view of the turbine of FIG . 19 ,
showing all components in a schematic side view and
BRIEF DESCRIPTION OF THE DRAWINGS partially in section ;
65 FIG . 21 is a perspective view of one embodiment of a
The following is a brief description of the drawings, piling -mounted hydrokinetic turbine mounted on a pivoting
which are presented for the purpose of illustrating the pedestal ;
 US 10 ,294 ,913 B2
10
FIG . 22 is a cross -sectional side view of the piling components , with no central shaft or gears and , as a result of
mounted hydrokinetic turbine of FIG . 21 , installed on a these and other features, can operate at a higher efficiency
pivoting pedestal; level than other comparable turbines .
FIG . 23 is a schematic perspective view of raft-mounted The designs of the hydrokinetic turbines of the invention
hydrokinetic turbine installed on an ocean barge , with both 5 are readily scalable in size, which means they can easily be
turbines operating; adapted and optimized for any specific geographic area and
FIG . 24 is a schematic perspective view of a raft-mounted for different flow speeds and flow volumes .
hydrokinetic turbine installed on an ocean barge with port The present invention includes several different installa
side turbine operating, and with starboard side turbine in tion methods, making the device suitable for usage in many
maintenance position ; 10 different types of locations and conditions with any navi
FIG . 25 is a perspective view of the raft-mounted hydro - gable water depth .
kinetic turbine installed on ocean barge, with starboard side The turbines of the invention are designed to be very
turbine operating, and with port side turbine in maintenance environmentally friendly and to have practically zero impact
position ; on marine life, the seabed or riverbed and its surroundings.
FIG . 26 is a perspective view of the raft -mounted single 15 They are preferably equipped with wildlife and debris
hydrokinetic turbine installed between two ocean barges ; excluder, a safe passage or way through for smallmarine life
FIG . 27 is a perspective view of the buoyant in installation and electro -magnetic radiation (EMF) shielding. The exte
of a hydrokinetic turbine installed on a submersible raft; rior is preferably painted with non -toxic anti - fouling coat
FIG . 28 is a schematic perspective view of a structure ing.
mounted hydrokinetic turbine installed on a bridge across a 20 Due to the unique design , materials used in the construc
river ; tion and coatings applied , these devices require minimal
FIG . 29A is a schematic perspective view of a buoyant maintenance .
installation of a hydrokinetic turbine mounted on a submers The present invention , in one aspect, relates to a hydro
ible raft installed on an ocean bed or river bed ; kinetic turbine intended to be placed underwater, in a fixed ,
FIG . 29B is a schematic perspective view of a buoyant 25 floating, anchored or towed configuration , in a stream of
installation of a buoyant hydrokinetic attached directly to the water flow that preferably has a minimum flow speed of
tethers installed on an ocean bed or river bed ; about 0 .25 m /s. The invention also relates to certain turbine
FIG . 30 is a perspective view of one embodiment of a components, to a method for designing /producing such
towed installation of a hydrokinetic turbine being towed turbines, as well as to a method of using same. Of course this
behind a vessel; 30 device will produce more energy with greater flow speeds.
FIG . 31 is a perspective view of a hydrokinetic turbine These turbines may be installed in any numbers . They
with a hydrofoil shape solid center hub and hydrofoil shaped may be used as single units or may be installed as a " turbine
vanes to hold the hub in place ; and array ” or a “ turbine farm ” that may consist of multiple
FIG . 32 is a schematic side view of a hydrokinetic turbine turbines and may be up to hundreds of units . The turbines
with a hydrofoil shaped solid center hub and hydrofoil 35 may be generating electricity together or separately.
shaped vanes to hold the hub in place ; The design of these turbines is scalable and may be
FIGS. 33A and 33B are, respectively, a schematic side produced as a small unit of any size , but practically speak
view of an accelerator shroud, diffuser and center hub ing, at least about 30 cm of rotor section diameter, and may
initially selected for a 6 kn current, and a corresponding be any size of rotor section diameter that is practical and
view of an accelerator shroud , diffuser and center hub that 40 appropriate for a particular application at a specific location .
have been optimized for a 3 kn current; The device may be a large unit of any size up to at least about
FIG . 34 is a schematic side view and front view of a rotor 30 m of rotor section diameter or more .
blade optimized for a 1 . 5 m rotor section diameter turbine to The invention provides an improved flow acceleration
be used in a 3 kn current; system developed by Applicant, that uses hydrofoil shapes
FIG . 35 is a more detailed schematic side view of an 45 on many of the key components of the turbine and most
accelerator shroud , diffuser and center hub optimized for a preferably on most or all of the components over which or
1.5 m rotor section diameter turbine to be used in a 3 kn through which the water flows. These components that may
current, utilizing the rotor blade of FIG . 34 . be hydrofoil shaped are called : the rotor blades (34 ), the
FIG . 36 is a graph comparing power output from hydro center hub ( 36 ), the rotor blade shroud (38 ), the accelerator
turbines according to the invention in comparison to similar 50 shroud ( 20 ), annular diffuser ( 40 ), the wildlife and debris
machines not having hydrofoil shrouds, at varying water excluder ( 10 , 18 ), the tail rudder (60) , the support structure
velocity . (50 , 52) , the support piling (54 ). Some of these components ,
FIGS. 37A and 37B illustrate 2 - D test results of CFD such as the rotor blades or the accelerator shroud , can
analysis of flow acceleration , in velocity and in pressure , advantageously be hydrofoil shaped in order to optimize the
respectively , of an embodiment according to the invention . 55 extraction of energy, while other components such as the
FIGS. 38A and 38B illustrate CFD measurements, in wildlife and debris excluders may be hydrofoil shaped in
velocity streamlines and pressure fields, respectively , of an order to reduce or eliminate turbulence that could negatively
embodiment according to the invention . affect another component or components .
FIGS. 39 and 40 show pressure differential on the front of The hydrodynamic principles that apply to this design are
the blades and on the back of the blades, respectively , in 60 valid for any size to which this hydrokinetic turbine is scaled
CFD testing. and whatever the flow speed of the water is. With appro
priate change in the shapes of these hydrofoil shaped com
DETAILED DESCRIPTION OF PREFERRED ponents, this hydrokinetic turbine can be adapted and opti
EMBODIMENTS OF THE INVENTION mized to the flow conditions of a specific site and to the size
65 of turbine required . The changes to the hydrofoil shapes are
The devices according to the invention are characterized advantageously made to one or more of the rotor blades , the
by a unique flow acceleration system and other unique accelerator shroud , the center hub and /or the annular dif
 US 10 ,294 ,913 B2
12
fuser. The changes, which in some cases can be relatively LIST OF PARTS
small and may consist in increasing or decreasing the chord
length and / or the chord thickness of some hydrofoils and /or
changing the angle of attack / incidence of the hydrofoils
according to the speed of the water flow and the required 55 10 forward wildlife and debris excluder
12 forward ring of excluder for attachment of the deflector rods
size of the turbine. This means that the design of specific 14 hydrofoil shaped deflector rods
embodiments according to the invention may change rela 15 distance between deflector rods
tively or even very little in appearance , butwill work exactly 16 rear/aft ring of the excluder for attachment of the deflector rods
18 rear/aft wildlife and debris excluder
the same way regardless of the size of the turbine or speed 20 complete accelerator shroud
of the water flow , as long as the proportions in size and 21 S -shaped /double-curve of hydrofoil shape accelerator shroud
position of the components relative to each other and the cross -section
position between the individual parts are maintained and 22 entrance duct/forward fairing of accelerator shroud
23 stator housing center section of the accelerator shroud
remain unchanged or very similar. 24 non - S -shaped hydrofoil shape accelerator shroud cross -section
The output of the turbine will increase in proportion with 25 metallic windings of the stator
the surface area of the rotor blades; this means that the 26 9 roller/ball bearings (3 thrust bearings forward , 3 thrust bearings aft ,
3 alignment bearings )
driving force that determines how many kilowatts or mega 28 aft fairing/aft section of accelerator shroud
watts a turbine produces is not in proportion to its diameter, 29 feather edge of accelerator shroud
30 complete main rotor section with hydrofoil shaped blades, rotor blade
but in proportion of the surface area of the rotor blades shroud with recess for permanentmagnet installation , hydrofoil
exposed to the water current. The output of a turbine 20 center hub
increases by the square of the diameter ; in other words a 32 ring of permanent magnets mounted in recess on rotor section
turbine that is twice as big in diameter will put out four times 33 tip of rotor blades
34 hydrofoil shaped rotor blades
the electrical power . This property of the design makes the 35 cross -sections of hydrofoil shapes of rotor blades
turbine scalable to almost any size that is practical and 36 hydrofoil shaped center hub
usable in a body of water with changes to the hydrofoil 25 3738 open center of main rotor section
rotor blade shroud with recess for permanentmagnet installation
shapes which are often relatively minor changes . 39 root of rotor blades
The design and the use of these particular shapes of the 40 annular diffuser with hydrofoil shaped cross-section
hydrofoil parts do not only eliminate the tip vortex of the 42 2nd annular diffuser
44 3rd annular diffuser
rotor blades but also accelerate water flow through the rotor 50 tubular support structure for various mounting purposes
section of the turbine due to the fact that the accelerator 51 hydrofoil shaped attachment rods between turbine components and
support structure
shroud , in combination with the annular diffuser , creates an 52 support piling for pivoting
area of low pressure at the exit of or behind the turbine that 53 waterproof
piling
plug for removal, rings and brushes for pivoting inside
is preferably further amplified by the hydrofoil shaped 54 floating raft or ocean barge
center hub . These components together create a synergy to 35 55 support structure for rotating on a raft /barge installation
56 cranes for turbine rotation on raft/barge installation
increase the water flow even more . The water flow that is 58 submersible raft for buoyant installation
already slightly accelerated at the entrance of the turbines 59 seabed mooring or screw -type anchor
through the funneling effect of the entrance duct is further 60 turbine tail rudder to orient turbine into the direction of the water
flow
accelerated by this low - pressure area behind the turbine that 40 62 winglets attached the turbine for towing installation
creates a suction to pull the water through the rotor section 64 buoyant
fixed tether and mooring for barge/raft mounted installation or
installation
from behind at even greater speed . In the case of the 66 rolling tether to submerge turbine by shortening or lengthening
preferred use of the hydrofoil shape of the parts , the designs 72 for surfacing
incidence/angle of attack of hydrofoil blade
according to the invention achieve a very large mincrease in
edde 45 74 chord of hydrofoil/length of chord
flow speed through the rotor section of the turbine where the 75 length of rotor blade
hydrofoil shaped blades are positioned . No other known 7876 thickness of hydrofoil cross -section /shape
twist of rotor blade / change of incidence
hydrokinetic turbine design has achieved this degree of flow 80 solid /bulbous center hub
acceleration . 82 hydrofoil shaped vanes to support that position solid center hub
83 diameter of diffuser entrance
The flow acceleration created by the unique shapes and 50 84 diameter of accelerator shroud entrance
combination of all the hydrodynamic elements remains the 85 overall diameter of center hub
same at any size of turbine. Computational fluid dynamic 86 profile /chord thickness of center hub
analysis of the designs ofhydrokinetic turbines according to 87 length of accelerator shroud
88 length of diffuser
the invention has proven that they accelerate the flow speed 89 length of center hub
through the rotor section to as muchhas
as about
aboutthree times the
three times the 55 90 profile/chord thickness of accelerator shroud
speed of the ambient flow speed surrounding the outside of 91 profile/chord thickness of diffuser
92 diameter of center hub exit
the turbine. This means that, for example , if this device was 93 diameter of accelerator shroud exit
placed in a 3 kn current the flow speed the through the rotor 94 diameter of diffuser exit
95 flow direction
section of this device would be up to 9 kn . The very 60
significant advantages of this increased current to the pro
duction of hydroelectric power are clearly apparent. The invention is preferably composed of four main com
The effects of each individual part as well as the effects of ponents , a ) a flow accelerator shroud , b ) an optional annular
interaction / cooperation and relation of the parts to one diffuser following the flow accelerator shroud , c ) a main
another are described in detail below , in connection with 65 rotor which is built into the accelerator shroud but is a
several exemplary embodiments of the invention , with ref- separate part, and d ) one or more optional wildlife / debris
erence to the accompanying Figures of drawing. excluders. Some of these components typically comprise
 US 10 ,294,913 B2
13 14
several different sub -parts that are assembled to be one part field behind the turbine. Because of the cooperation and
of the turbine . Additional features and advantages are resulting synergistic effect of the accelerator shroud and the
described below . These parts and features cooperative with annular diffuser, there is a greater augmentation of flow
and have an effect on one another in ways that are also speed through the rotor section . Generally, at a position
described below to produce the improved operation of the 5 relatively closely ( e . g ., from about 4 to 6 inches ) behind the
turbines according to the invention . trailing edge of the ( final) annular diffuser, which is prefer
The Flow Accelerator Shroud with the Annular Diffuser a bly a feather edge , the rear wildlife and debris excluder is
Referring now to FIGS . 1 -5 , 8 and 19 , the flow accelerator attached . There may be some instances in which itmay be
shroud ( 20 ) is an important part that embodies the most advantageous , e . g ., specific water flow conditions, to
complex hydrofoil shape . As used in the designs of this 10 employ one or more annular diffusers , such as second
invention , it preferably has an asymmetrical hydrofoil shape annular diffuser (42) and maybe even a third annular diffuser
and most preferably an S - shaped /double -curved hydrofoil (44 ), positioned one behind the other. ( FIGS. 6 - 7 )
shape (FIG . 5a , 21), or in other words a generally S -shaped The Rotor Assembly
double - curved configuration ( FIG . 9 ), to create a negative Turning now to FIGS. 10 - 15 , the hydrokinetic turbines of
pressure field behind the shroud in order to accelerate the 15 the invention preferably have an open center (37 ). In part,
water flow through the rotor section ( 30 ) of the turbine . The this is advantageous in the designs of the present invention
cross -section of the wall of the accelerator shroud may also because of the low speed that the blades travel through the
be a hydrofoil shape that is not an S -shaped double -curved , water near the center of the rotor section and therefore do not
but resembles much more conventional hydrofoil shapes create sufficient lift or enough energy worth extracting.
( FIG . 55 , 24 ). The accelerator shroud accelerates the flow of 20 Actually , the center portion generally has a negative effect
the water on the inside of the turbine in comparison to the on the rotor due to the extra drag it creates by a larger wetted
ambient flow speed around outside the accelerator shroud . surface and additionalweight needing to be moved through
The accelerator shroud is preferably composed of four the water . The extremities of the rotor blades (34 ) travel
pieces: entrance duct (22), the stator housing ( 24 ) , the rotor through the water at a higher speed and therefore create
blade shroud ( 38 ) (FIG . 10 ) and the aft fairing ( 28 ). These 25 substantially more lift and allow substantially greater energy
four components together preferably form a single shape, extraction . Depending on the size of the turbine, the flow
which is preferably the asymmetricalhydrofoil of the accel speed at a location of the installation and other site -specific
erator shroud , which in certain preferred embodiments has needs, the ratio between open center and blade and hub size
the S -shaped /double -curved hydrofoil shape. All four pieces can be anywhere from about 40 % blade:60 % open space , to
are preferably faired together to form a perfectly smooth 30 about 80 % blade : 20 % open space . Turbines according to the
surface both inside and outside, over which the water flows invention advantageously use the major portion of the
without creating any significant turbulence . overall diameter along the perimeter of the rotor section to
The entrance duct ( 22 ) serves to funnel the water flow into produce lift, typically more than about 60 % and more
the rotor section (30 ) and to lead the water flow onto and preferably approximately 23 of the diameter. This leaves the
over the stator housing (24 ) on the outside of the accelerator 35 remaining minor portion , e . g ., in a preferred embodiment
shroud and over the rotor blade shroud ( 38 ) on the inside . approximately 1/3 of the overall diameter in the center open
This stator housing exterior surface and the rotor blade (37 ). Eliminating the center section of the rotor reduces the
shroud interior surface are part of the overall shape of the overall weight of the rotor and also reduces the wetted
accelerator shroud . The entrance duct also contains the surface area and drag that a solid profile section would
forward thrust bearings that guide the rotor section during 40 create . Therefore the designs of this invention create a more
operation. efficient rotor section that uses a smaller blade area with less
The stator housing (24 ) contains all the metallic, prefer - weight, with less wetted area and less drag, which can rotate
ably copper , coils (25 ) that comprise the stator of the annular at higher rpm rates and allow more energy to be extracted .
generator, as well as the conventional electrical wiring (not There is also a secondary effect that is of further benefit to
shown ) to convey the electrical energy generated out of the 45 the wildlife and debris excluder that is described below .
turbine . The stator housing also contains the rotational The center hub ( 36 , 80 ), that is preferably annular and
roller/ball bearings ( or other bearings or low friction poly - surrounds the preferably open center (37), is also used for
mer bushings ) ( 26 ) on which the rotor section rotates . attaching the rotor blade roots ( 39 ) . (FIGS . 11 - 12 and 31 )
The exterior surface of the rotor blade shroud (38 ) forms The center hub (80) that is solid preferably has a symmetri
part of the accelerator shroud but is a separate part that is 50 cal hydrofoil shape , whereas the center hub 36 with open
attached to the rotor blade tips ( 33 ) and rotates with the main center preferably has an asymmetrical hydrofoil shape , with
rotor inside the accelerator shroud . It is described in more the extrados being toward the outside of the turbine and the
detail below . intrados facing toward the center of the hub . The lift created
The aft fairing ( 28 ) located behind the stator housing ( 24 ) by the center hub helps further increase the negative pres
and rotor blade shroud (38 ) leads the water flow to the exit 55 sure field behind the turbine created by the accelerator
of the accelerator shroud (20 ) and preferably has a feather shroud (20 ) and the annular diffuser (40 ). This effect
edge (29 ) on the back end to avoid creating any turbulence increases the acceleration of the water flow through the rotor
or drag . The aft fairing also contains the aft/rearward thrust blade section and contributes to the synergistic effect and
bearings ( 26 ) ( FIG . 9 ) against which the rotor section is resultant higher power generation .
pushed while rotating 60 The rotor blade shroud (38 ) (also called the outer ring of
The annular diffuser (40 ) is also preferably an asymmetri- the main rotor ) is where the extremities /tips (33) of the
cal hydrofoil shaped ring and preferably has a greater blades ( 34 ) are attached . (FIG . 10 ) This rotor blade shroud
diameter than the accelerator shroud ( 20 ). The annular (38 ) forms a part of the hydrofoil shape of the accelerator
diffuser (40 ) is located behind the accelerator shroud and shroud ( 20 ). It is a separate element from the accelerator
preferably overlaps somewhat over the aft end of the accel- 65 shroud allowing it to rotate with the rotor blades (34), but the
erator shroud (20 ) . It works in a manner very similar to the surface of the rotor blade shroud is preferably perfectly in
accelerator shroud, further increasing the negative pressure line with the inside surface of the accelerator shroud (20 ) to
 US 10 ,294,913 B2
15
create one smooth curve of both inside surfaces, accelerator The Wildlife and Debris Excluder( s )
shroud and rotor blade shroud . The outside surface of the Referring now primarily to FIGS. 16 - 18 , a hydrokinetic
rotor blade shroud , which faces the stator housing ( 24 ) turbine that produces energy from a renewable source with
interior surface , is preferably recessed into the accelerator zero carbon emissions should be environmentally friendly
shroud and has a flat surface where the permanent magnets 5 not only to the natural resources and to the atmosphere , but
(32 ) are located which rotate past the copper coils (25 ) of the also to marine and wildlife . This invention deflects and
stator to produce the electrical energy. The rotor blade keeps any marine life and floating or submerged debris
shroud (38 ) also eliminates tip vortex and reduces drag and above a specified size out of the hydrokinetic turbine' s rotor
turbulence, resulting in higher efficiency and greater energy of the invention. The size ofmarine life or debris that cannot
extraction . 10 enter the nozzle section of the turbine is specified by the
Referring now to FIGS. 11 - 15 , the efficiency of the rotor spacing /distance ( 15 ) of the deflector rods ( 14 ) of the
blades ( 34 ) is increased by preferably using an asymmetrical forward and rear excluder. In this invention the deflector
hydrofoil shape , which is also preferably optimized , as rods , by design , run parallel to each other and are evenly
explained below . This shape , also called the chord or cross spaced over their full-length to ensure that no distance
section ( 35 ) of the hydrofoil , results in an increase of the 15 between the rods ( 15 ) is greater in one place than in another.
efficiency of each blade , reduces it in size and decreases the The distance of the spacing (15 ) is determined by the size
number of blades relative to other designs . A smaller rotor and the species of marine wild life as well as the size of
blade (34 ) has less wetted area , thus producing less drag . debris encountered to be excluded and to adapt to locational
The amount of lift a hydrofoil shape generates is determined needs of specific sites of operation . It will prevent any sea
by the shape of chord /cross -section (35 ) (FIG . 15 ), the 20 life such as fish , turtles, sea mammals and even divers that
length of chord (74 ) and the thickness of chord (76 ) of the are larger than the space ( 15 ) between the deflector rods ( 14 )
hydrofoil. ( FIG . 13 ) In designs according to the invention , from entering into the rotor section of the hydrokinetic
one or both , the length of chord (74 ) and / or the thickness of turbine from the front as well as from the back when a rear
chord (76 ) preferably change between the blade root ( 39 ) excluder is also employed .
and the blade tip ( 33 ). This optimizes the lift created by the 25 The present designs contrast with other previously known
hydrofoil shape in relation to the speed it travels through the designs, (see , e . g ., ( U . S . Pat. No. 3 , 986 , 787 , US 2010 /
water. The number of blades put into the rotor section of 0007148 A1, and U . S . D 614 , 560 ) which are characterized
designs according to the invention may vary depending on by deflector rods that are non -parallel , such that the openings
the size of the turbine and the flow speed of the water in a between the rods become bigger /wider towards one end of
particular application . 30 the excluder, thus not limiting the entry of marine life or
The angle /incidence (72 ) (FIG . 13 ) at which the rotor debris to a finite size . Some other prior art devices are
blades are installed is also a variable that can be adjusted for designed as concentric circular deflector rods (see , e. g ., U . S .
the purpose of optimizing the angle of attack or incidence of D 304, 322 and U .S . Pat. No . 5 ,411,224 ) which define a finite
the blade traveling through the water. It is preferred to use size of opening , but such configurations do not effectively
an optimum angle which is determined by the rpm of the 35 shed off all wildlife and debris like the deflector rods
rotor to produce a laminar or at least a near laminar flow of according to the present invention , which are aligned
the water over the blade surface . If this flow is turbulent or obliquely with respect to the flow direction . In the concentric
significantly non - laminar, the hydrofoil creates less lift, and design , wildlife or debris can easily become lodged between
therefore less energy can be extracted . The tip of the blade the rings. In the designs of the invention, the exact size of
travels through the water faster than the root of the blade, 40 marine life or debris to be excluded can advantageously be
due to the fact that it travels a longer distance to complete selectively predetermined by the distance ( 15 ) chosen
one rpm . Therefore the incidence of the blade advanta - between the deflector rods (14 ) .
geously decreases gradually from the root ( 39 ) of the blade Ocean currents and river currents contain floating debris
to the tip ( 33 ) of the blade, in order to be at the optimal ofmany sorts. This debris may be floating at the surface or
angle . This change in angle is called the twist (78 ) of the 45 submerged at different depths. Therefore , it is preferred to
blade . The twist is preferably designed to create a rotor blade keep such debris out of the rotor section of the hydrokinetic
maximum lift at every cross - section and therefore to turbine to the greatest extent possible , in order to prevent
increase the efficiency and the power extraction . damage to the turbine and to ensure continuous and unin
In order for hydrofoil shapes according to the invention to terrupted electrical output. The designs according to the
be optimal while they travel through the water at different 50 invention effectively deflect and keep out any debris above
speeds, they preferably have different lengths of chord (74 ) the specified size ( 15 ) of the spacing of the deflector rods .
and different thicknesses of profile / chord (76 ). Preferably, The hydrokinetic turbines according to the invention
the thickness (76 ) of the blade increases and /or the chord preferably have two wildlife and debris excluders, one (10 )
length (74 ) increases from the root of the blade toward the in front at the entrance ( 22 ) of the turbine and one ( 18 )
tip of the blade , in order to increase the surface area where 55 behind at the exit of the turbine . The frontwildlife and debris
the blade travels though the water with higher speed and excluder (10 ) is located in front of the turbine protecting the
creates the greatest amount of lift. Thus, the blades most entrance (22 ) of the accelerator shroud ( 20 ), and is attached
preferably increase in both size and thickness as they extend to the front end of the accelerator shroud as well as prefer
radially from the hub . These increases in chord length and ably to the support structure (50 , 52 ) of the turbine . The
thickness result in higher efficiency and greater power 60 deflector rods ( 14 ) of the excluder may be made of metal,
extraction . fiberglass or synthetic materials with different diameters
The rotor blades hydrofoil shape (35 ), the length of chord depending on the turbine size; from about 1/4 inch on a small
( 74 ), the thickness of profile /chord (76 ), the degree of turbine and up to about 2 inches on very large units . The
incidence (72 ) , and the twist (78 ) of each rotor blade , and the deflector rods are preferably hydrofoil/ teardrop ( 14 ) shaped
number of blades can advantageously be varied for each 65 in cross -section (FIG . 18 ) with the blunt end pointing into
application , in order to adapt to site - specific flow conditions the water flow and the sharp ends being the trailing edge .
of the water and other locational needs. This configuration serves to avoid turbulence in the water
 US 10 ,294 ,913 B2
flow that could disturb the efficiency of one or more other of a fixed tail rudder (60), which is preferably hydrofoil
components , such as the accelerator shroud (20 ), the annular shaped and will orient the unit directly into the direction of
diffuser (40 ) and / or the rotor blades ( 34 ). the stream of water flow . This feature allows the device to
The first/ forward wildlife and debris excluder ( 10 ) is point exactly into the direction from which the current is
preferably built so that the deflector rods on the forward end 5 coming, so that the water passing over the hydrofoil shaped
of the front excluder ( 14 ) form a generally cone-like shape . components of the turbine flows at the optimal angle over all
The deflector rods on the forward end are attached to a small hydrofoil shaped surfaces . This optimizes the pressure dif
ring ( 12 ) that preferably has the same inside diameter as the ferential between the two sides , increases the synergistic
specified distance ( 15 ) between the insides of the deflector effect of the hydrofoil shapes and helps to assure a laminar
rods. On the back end , the deflector rods are preferably 10 flow of the water.
attached to a large ring ( 16 ) which is preferably greater The design of the hydrokinetic turbines of the invention is
diameter than the annular diffuser ( 40 ). The slope of the such that the flow of the water is always from the same side ,
cone- like shape created by the difference between the for - i.e ., unidirectional. This allows the turbines to take great
ward ring ( 12 ) and the aft ring ( 16 ), to which the deflector advantage of many asymmetrical hydrofoil shapes and
rods ( 14 ) are attached , can be altered to adapt to different 15 hydrodynamic effects, which , when combined together,
environmental needs. The front excluder is preferably posi- result in a much more efficient turbine . Bi- directional tur
tioned so as to slightly overlap the annular diffuser with a bines cannot use asymmetrical hydrofoil shapes, and are
gap that is approximately the same size as the distance ( 15 ) therefore less efficient.
between deflector rods , in order to maintain a finite size of The turbines according to the invention do not only utilize
wildlife and debris allowed to enter. It is designed to be 20 the Venturi/Bernoulli effect much better due to their unidi
cone -like shaped in order to shed off and divert any wildlife , rectional flow , but they also increase the flow velocity
debris , sea grass or whatever else may be floating in the further with the use of the preferred asymmetricalhydrofoil
stream of water about to enter the turbine. shaped accelerator shroud and /or annular diffuser, and/or the
The second / aft wildlife and debris excluder 18 (FIGS . 16 preferably hydrofoil shaped center hub .
and 18 ) is located behind the turbine exit and is attached to 25 The annular generator design preferably has magnets (32)
the trailing edge of the ( final) annular diffuser . The rear mounted on the rotor blade shroud (38 ) and copper or other
excluder is preferably also comprised of a grill or mesh of metallic coils ( 25 ) in the stator housing (24 ) which is
parallel rod members that are spaced apart from one another preferably located inside the accelerator shroud (20 ). This
by the same pre -determined distance as the rods (14 ) in the design eliminates the need for a gearbox or transmission or
front excluder, and in the case of the rear excluder, the most 30 hydraulic systems to mechanically extract and convey the
preferred configuration is a generally planar one. The rear energy out of the turbine . Gearboxes , transmissions and
excluder prevents larger sea life from entering into the rotor hydraulic systems create friction that consumes a portion of
section from behind , even against the direction of the water the energy that the turbine produces. By the usage of an
current or also in the case of no current as for example annular generator, the invention minimizes these friction /
during the change from an incoming to an outgoing tide. The 35 transmission losses and creates a more efficient turbine or
deflector rods of the excluder are spaced to the same generator. The electrical energy generated directly inside the
specified distance (15 ) as the forward wildlife and debris turbine is transmitted through electrical wires (not shown )
excluder to prevent any wildlife or debris larger than the eliminating friction / transmission and power losses. The
specified distance from entering into the rotor section . All energy produced is then transmitted for conditioning to an
the deflector rods ( 14 ) of both of the excluders preferably 40 inverter/ transformer that typically is located outside the
have a hydrofoil shaped cross - section , to minimize the turbine , wherever deemed practical. The preferred design
creation of turbulence and vortices that would negatively according to the present invention also eliminates the need
affect hydrofoil shapes that may be present on one or more to have center bearings , which thereby eliminates the need
of the other components, such as, the rotor blades , the for any fixed structure whatsoever (e .g ., shaft or hub ) located
accelerator shroud , the annular diffusers , and /or the center 45 within the flow area through the turbine. The absence of any
hub . fixed structure furthermore means that no struts or other
The smaller sea life that can pass through the spacing ( 15 ) elements are needed to support that fixed structure .
of the deflector rods is advantageously provided a secondary The accelerator shroud ( 20 ) , the annular diffuser (40) , the
path for safe passage through the cylindrical center hub ( 36 ) hydrofoil shaped center hub ( 36 , 80 ) and the rotor blades
having an open center (37 ) in the majority of the depicted 50 ( 34 ) of this turbine are preferably constructed of composite
turbine embodiments . The open center of the rotor section is building materials , such as , e. g ., carbon fiber, aramid fiber,
described above. Because the water flow speed in the center fiberglass or similar in either solid fiber and resin or over
hub is faster than outside where the blades are situated , structural foam core material or honeycomb core material.
smaller sea life will be aspirated through that opening and Some parts such as the stator housing are preferably hollow
can exit unharmed . The diameter of the open center may 55 to accommodate the copper coils ( 25 ) of the stator. Other
vary widely , withoutmaterially affecting the performance of parts such as the entrance duct ( 22 ), the aft fairing ( 28 ) of the
the turbine . The optimum diameter can be calculated for accelerator shroud ( 20 ) and the annular diffuser ( 40 ) may in
each application , and in certain preferred embodiments is some preferred embodiments be solid or sandwich construc
typically approximately 1/3 of the overall diameter of the tion and remain hollow on the inside , with the option to be
rotor section . The accelerated flow of the water through the 60 selectively filled with water when submerged . With the
open center (37 ) serves to safely convey small wildlife and appropriate ( for the water depth ) structural bracing on the
small debris through the inside of the turbine . inside of the hollow parts, they will be able to withstand the
No matter which installation method is chosen , the tur- water pressure of being submerged. In the case of sandwich
bines according to the invention are preferably automatically construction , these composite materials utilized are naturally
self -orienting, meaning that they will always point exactly 65 buoyant and will keep the turbine floating. Although com
into the direction from which the water flow is coming. This posite materials are ideally suited for the construction of this
is preferably achieved by the installation behind the turbine hydrokinetic turbine , the device may also be built of steel,
 US 10 ,294 , 913 B2
19 20
aluminum , titanium or other metal alloys deemed suitable common range of operation , it is especially important to
for a specific application . The overall buoyancy of this optimize the design of the shroud member (and other
turbine will mostly be positive and may use ballast to keep components and relationships ), in order to maximize the
it submerged . The turbine may also be submerged by allow - relative increase in power output.
ing hollow compartments to be filled with water. The 5 Another way to demonstrate the increased efficiency of
installation of an appropriate amount of ballast or water the turbines of this invention is in a comparison to other
filling of certain compartments will allow the overall buoy - highly efficient commercially available turbines. One of the
ancy of the turbine to be controlled to selectively make the most successful hydrokinetic turbine manufacturers and
turbine become either positively buoyant , neutrally buoyant installers in the world has recently developed a new design
or negatively buoyant, for different applications. 10 of hydrokinetic turbine which it claims is their most effi
The preferred self-orienting feature of the device allows cient. It is a bidirectional turbine that has a 16 m diameter
this turbine to be a unidirectional flow turbine . In a unidi rotor section with an exterior shroud and a open center hub
rectional turbine , the existence of a water flow that is always which is claimed to be able to produce 2 .2 MW . Utilizing the
coming from the front of the turbine allows the use of design methodology of the present invention , a turbine
asymmetrical or unidirectional hydrofoil shapes in the 15 having the same 16 m diameter rotor section will produce
design . Accordingly , any or all of the basic components, i.e ., 3 . 88 MW , according to our “ theoretical calculations ” . This
the rotor blades , the accelerator shroud, the annular diffus represents a 76 % increase in electrical output for the same
ers, the hollow center hub , the tail rudder and/ or the wildlife size turbine.
and debris excluders can advantageously comprise , to at Below is a calculation used for output prediction for the
least some degree , asymmetrical hydrofoil shapes. The 20 hydrokinetic turbine designs according to the invention :
asymmetrical or unidirectional hydrofoil shapes are much
more efficient than symmetrical and bi- directional hydro
foils . Theoretical Calculations of turbine output in relation to water flow speed
The relationship and cooperation between those elements Incoming Flow Velocity 3 Knots
that may include the asymmetric hydrofoil shapes, i.e., the 25 Turbine Inside Diameter 16 .000 Meters
accelerator shroud , the rotor blades, the annular diffuser, the Predicted Turbine Power 3,882 ,476 W 3 . 88 MW
hollow center hub and /or the wildlife and debris excluders Nozzle diameter ratio 1.473:1
produce a mutually beneficial and synergistic effect, which Nozzle influence , Velocity
Flow tube available
2 .948 : 1
23 .573 M
is enhanced as more of these elements are provided with the Flow Velocity in Nozzle 8 . 844 Knots 4 .549746 M / S
asymmetric hydrofoil profiles . In the most preferred 30 Turbine Area 201.062 M2
embodiments , all five of these elements benefit from each Power Coefficient and Betz Law
other ' s presence , and when combined together , their effect is
amplified to create a much greater negative pressure field Density = 1025 . 15 Kgm3
/
Velocity = 4 .550 M / S
behind the turbine than they would create individually or Diameter = 16 .000 M
separately . In other words the effect of the plurality of 35 Max Possible % (Betz ) 0 . 59 Cp
elements together is greater than the sum of the plural Betz Limit power P = 5 , 751, 816 W
elements individually . This synergistic effect creates a Predicted Turbine Cp 0 .4 Cp
greater acceleration of the flow through the rotor section
where the asymmetricalhydrofoil shaped blades take greater Installation Methods:
advantage and are able to rotate at higher speed or RPM . 40 The hydrokinetic turbines according to the invention can
These combined effects result in a synergistic effect that is be installed in practically any moving body of water or can
mutually beneficial and that results in much higher effi - be moved through the water to create usable output. There
ciency that allows greater energy extraction thanks to this are five primary ways of installation and deployment meth
“ Flow Acceleration Technology ” developed by the inventor. ods for these hydrokinetic turbines :
With reference to FIG . 36 , the table shows how , for one 45 Piling-mounted (FIGS. 21 , 22 ): The turbine unit or units
preferred embodiment, the presence of the hydrofoil shaped can be a piling mounted installation , which consists of a
accelerator shroud results in an exponential acceleration of piling (52 ) driven into the ocean floor or riverbed that has a
the flow velocity through the nozzle section , compared to the set of rotational thrust bearings and a compression pivoting
ambient flow speed . bearing on the top (53). A larger pipe that that is attached to
The data represented in FIG . 36 illustrates the difference 50 the mounting structure (50 ) on which the turbine sits sleeves
in power output with increased ambient current velocity for over that fixed piling (52) and the bearings (53) . The
between 2 different designs of hydrokinetic turbines with a mounting structure (50 ) can unbolt from the pipe (52 ) and
1 . 5 meter diameter rotor. The line with squares represents a has an electrical plug (53 ) inside the pipe that can be
hydrokinetic turbine that simply has a hub and 3 blades , with unplugged for maintenance and turbine removal. This instal
no shroud that all (which is the most common use designs 55 lation allows the turbine unit to pivot and the turbine can
used in hydrokinetic turbines worldwide ). The line with freely rotate 360° to orient itself exactly into the direction of
triangles demonstrates the output of this invention that the water current. This type of installation also has a very
utilizes hydrofoil shaped accelerator shroud , annular diffuser small seafloor footprint and minimal impact on the environ
and open center hub . This is the same relationship for the ment. In this installation the electrical power is transmitted
same rotor assembly contained within an accelerator shroud 60 through a set of copper rings and charcoal brushes (53 )
having a hydrofoil shape similar to that depicted in FIG . 35 . inside the sleeve to avoid a cable being twisted and any
It is seen that the increase in power is according to an restraint on the pivoting action .
exponential power on the order of 3 . It can also be seen that, Floating structure -mounted (FIGS. 23 , 24 , 25 , 26 , 27 ) :
in the lower range of current velocities , (e . g ., around 3 kn The turbine unit or units can be attached to any kind of
which represents the vastmajority of applications for hydro - 65 floating structure such as an ocean barge , a raft (54 ), a ship
turbines of this type), the comparative relationship is less or a vessel floating on the surface of the water. These devices
sensitive to changes in current speed . Therefore , in this can either be anchored to the seabed or riverbed (59) or held
 US 10 ,294 ,913 B2
21 22
in place by thrusters coupled to GPS location devices similar therefore would orient the turbine to optimally create the
to oil rigs or tied to any structure in the ocean or in a river flow from front to back through the unit. Instead of the single
or along shore . There are two types of raft mounted instal- rudder that is usually located behind the exit of the turbine,
lations, one is on a longitudinal pivot ( FIG . 23 , 24 , 25 ) and there can alternatively be 2 or 4 winglets (62 ) attached to the
the other is on the transverse pivot (FIG . 26 , 27 ) . Preferably, 5 outside of the annular diffuser, with one winglet on each side
the raft mounted device either employs a hoisting system or and one winglet on top and bottom . These winglets (62 )
a crane that is installed on deck or a helical gear driven prevent the turbine unit itself from rotating as it is towed
device to pivot the turbine onto the deck . One type of through the water, thereby ensuring that only the rotor
installation utilizes only one raft or barge, whereas the section is rotating .
transversely mounted system employs two rafts or barges, 10 Maintenance Procedures :
with the turbine unit mounted in between them . Depending The hydrokinetic turbines of the invention require only
on the size of the turbine , the location or the operator 's minimal maintenance , due to the design of the components
preference , one type of installation can be better than the and because the preferred composite construction materials
other. For larger systems it is usually advantageous to use are virtually corrosion free . However just like everything
two rafts or platforms and mount the turbine between the 15 that is submersed in the ocean over a certain length of time
two on the central transverse axis (FIG . 26 , 27 ), on which the fouling and marine growth will occur . These hydrokinetic
turbine can be pivoted 180° to be above the water for turbines are coated with non -toxic antifouling paints , but
maintenance or repair. For smaller units the turbine or still need periodic cleaning of the surfaces to ensure optimal
turbines can be mounted over the side of the floating functionality and output. These units can be pressure washed
structure and be pivoted on the longitudinal axis (FIG . 23 , 20 by a diver while they are submerged which allows them to
24 , 25 ), to be placed on the deck of the structure for remain underwater or they can be broughtto the surface and
maintenance or repair . be pressure washed by ground personnel. Other than peri
Land- based structure -mounted (FIG . 28 ): The turbine unit odic cleaning, these units require very little maintenance .
or turbine units can also be mounted to a land - based struc - Depending on the type of installation , the preferred main
ture such as a seawall, a shoreline or be attached to a bridge 25 tenance procedures may vary , as discussed below .
pillar or other structures installed in the stream of an ocean In the case of a piling -mounted installation ( FIG . 21, FIG .
current or in a river current. The device can preferably be 22 ), it is preferred to utilize a special maintenance vessel
mounted on any of these fixed structures by at least two (also designed by the Applicant) that is a catamaran vessel
different methods. Support structure to which the turbine is having a removable deck between the two hulls, and a gantry
attached can be mounted either to one or two rails attached 30 with a hoist installed over that removable deck . The vessel
to the fixed structure on which the unit is lowered into the can be positioned above the turbine that needs maintenance ,
water and raised up out of the water for maintenance or and the turbine unit can be lifted by reaching through the
repair, or it can be mounted on a pivot which also allows the opening in the deck between the two hulls and hoisting the
device to be pivoted into the stream of water and back out turbine onto the boat. The electrical wire connecting the
of the water for maintenance or repair . Either way, the units 35 turbine to shore leads to copper rings and brushes (53 ) that
are held in place in the up position by a latching mechanism , are located inside support piling for pivoting (52 ) has a
whereas in the down position it can rest on some end stops . waterproofplug (53 ) that can be unplugged when the turbine
The cable connection preferably goes to the base structure is lifted up by the maintenance vessel located above. On the
and from there to a transformer for conditioning. vessel, the turbine that was just removed from the piling can
Buoyant installation (FIG . 29 ) : The turbine unit or turbine 40 be put off to one side, onto one of the hulls , and a spare
units can be made naturally buoyant due to the composite turbine sitting ready on the other hull can be lowered
construction materials that can be employed for the con - through the opening and plugged and bolted back onto the
struction of any or all the parts . This allows the device to piling, from which the first unit was removed .
float at any given depth determined by the length of a tether In the case of a raft-mounted installation , it is preferred to
(64 & 66 ) which is attached to a foundation / seabed mooring 45 attach the support structure (50 ) of the turbine either longi
(59 ) or screw - type anchor , or any other fixed device on the t udinally alongside the raft or transversely between two rafts
seabed or the riverbed . The two - part tether serves two (FIGS. 23 , 24 , 25 , 26 , 27 ) In each case , a support structure
purposes: the fixed tether (64 ) and the rolling tether (66 ) is (55 ) is used that is mounted on pivot points with bearings
to hold the device submersed at the desired depth and to (55 ), which allow the unit to pivot around a central axis
transmit electricity from the generator unit to the base and 50 either 270° in the case of longitudinally mounted units (FIG .
then to shore . This tether (64 & 66 ) has 2 components ; a 23 , 24 , 25 ), or 180° in the case of transversely mounted units
primary fixed tether (64) that is a fixed length between the ( FIGS. 26 , 27 ). A locking mechanism is used to hold the
turbine and the secondary rolling tether (66 ) which is a units in place when submerged for power generating, as well
rolling mechanism that is attached to the base and is the as when surfaced for maintenance or repair. To surface the
equal in length to the distance between the water surface and 55 unit, a crane or hoist (56 ) installed on the raft is employed
the desired depth where the turbine is to be held . When the that can attach to the support structure of the turbine . Once
secondary tether is unrolled the turbine is allowed to float to unlatched in the submerged position , the crane can pull the
the surface for maintenance or repair . The device may also unit out of the water by pivoting the unit into the mainte
be attached on a submersible raft (58 ) or submerged flotation nance position where it can be secured by latching into
device (58 ), to hold the turbine suspended in midstream . The 60 position .
same tether mechanism can be utilized in this case . In the case of a fixed structure mounted installation ( FIG .
Towed installation ( FIG . 30 ): The turbine unit or turbine 28 ), the turbine units can be maintained or repaired by at
units can also be towed behind a vessel or be dragged least twomethods. One method is to have a floating platform
through the water by other devices that propel the device or raft that is put in place after the turbine is hoisted out of
through water that is not moving , to artificially create a 65 the water, either by sliding the turbine mounted to the
water flow through the device . The towing cable is typically support structure upwardly on the rails of the fixed structure ,
attached to the front of the wildlife and debris excluder , and or to make the units mounted on the support structure
 US 10 ,294 ,913 B2
23 24
upwardly out of the water. The other procedure is to have a ments that are representative of designs for use at these two
platform that is attached to the fixed structure that can swing most (i. e., nearly all) commonly encountered flow speeds.
out of the way for raising the turbine units out of the water Of course, following the teachings of this application , the
and then be repositioned for servicing. turbines according to the invention can be optimized for any
In the case of buoyant installation , there are also at least 5 flow speed , which from a practical standpoint includes
two ways of servicing the turbine units . In the case of a currents ranging from about 1/2 kn to up to about 12 kn of
buoyant turbine that is tethered to the seabed or the riverbed flow speed .
by a fixed tether (64 ) that is attached to the rolling tether (66 ) There are many standard algorithms used in fluid dynam
is lengthened by unrolling the pulling mechanism ( described ics to calculate the shape of hydrofoils , and the standard
in the installation description above ) and bringing the tur- 10 textbooks and databases contain complete information and
bine to the surface . Once at the surface , the turbine unit can tables pertaining to such calculations and known designs .
be hoisted onto the deck of a vessel for maintenance or These need not be discussed in the present context, since
repair. In the case where the turbine units are attached to a they are well known to those skilled in the art. However , as
submerged raft ( 58 ) or flotation device , the rolling tether is discussed below , in some embodiments , the present inven
(66 ) pulling mechanism unrolled in the samemanner as with 15 tion utilizes these algorithms/ databases in a novel design
a buoyant turbine, and once at the surface the turbine units regimen , as a starting point to design novel hydrofoil shapes
can be pivoted up onto the platform for servicing. that serve as the so - called “ initial” designs in the first stages
In the case of a towed installation , the towing line of the hydroturbine design process .
attached to the turbine unit is hauled in to bring the turbine According to onemode , the design process typically starts
unit alongside or behind the vessel, where it is typically 20 out with hand -drawn sketches (usually but not necessarily
picked up by a hoist or a crane mounted on the vessel. The novel) based upon conventional fluid dynamic consider
turbine is then preferably placed on the deck of the vessel for a tions, which sketches are selected based upon the novel
maintenance or repair . principles according to this invention . The selected sketches
Methodology of Design are subsequently entered into a computer program of the
The way in which the turbine units of this invention have 25 type called a 3 - D modeling program , one example of which
been designed is believed to be novel and unique . After over is called “ Rhino 3 - D ” or “ SolidWorks” . This results in a first
30 years of experience as a designer working in the field of version of the “ initial” designs.
fluid dynamics , and after having created and built many Alternatively, the first version of the “ initial” design can
different types of hydrofoils in his professional life , the be produced by selecting various different hydrofoil shapes
Applicant came to the basic concepts underlying the design 30 from one of the databases, such as the archives of the
of the turbines according to the invention . With these basic National Advisory Committee for Aeronautics (NACA ),
design concepts, he believes that his turbine designs accord again based upon the same conventional fluid dynamic
ing to this invention provide hydrokinetic turbines that will considerations that are employed in fashioning the hand
surpass and outperform any other design that is currently in drawn sketches, but again the shapes are selected ( from
existence. 35 among a huge number) based upon novel design consider
Today there are many environments in which hydroki- ations taught in this application . The shapes of these first
netic turbines are used that are characterized by a reversing version , " initial” intuitive hydrofoil shapes ( irrespective of
current flow , and as a result much of themodern design work how arrived at) are modified with the 3 - D modeling soft
has focused on providing bi- directional turbines that can ware , such as Rhino 3D or SolidWorks and analyzed in a
effectively be employed in such environments , mainly tidal 40 2 - D flow analysis program , such as “ Java Foil” or the like,
currents . Consequently , many of these bi -directional tur - and other similarly commercially available software prod
bines either embody little or no hydrofoil- embodying com ucts for this purpose. This modification proceeds by viewing
ponents, or if they do, the hydrofoil designs are necessarily the selected “ initial” profiles in 3 - D and making modifica
symmetric . However, the cross- section lift coefficient of an tions thought to be favorable based upon fluid dynamic
asymmetric or cambered hydrofoil is greater than that of a 45 considerations, so as to maintain laminar flow and avoid
symmetric hydrofoil. This design of the unidirectional turbulence , while maintain maximum flow speed . As a result
hydrokinetic turbines according to the present invention of this first stage , modified “ initial" designs are created that
takes advantage of that phenomenon . represent new (novel) and unique shapes of hydrofoils
It was determined that it made themost sense to primarily according to the principles of the invention , which are then
optimize hydrokinetic turbines according to the invention 50 made into an annular or a nozzle shape , for the purpose of
for a 3 kn current (e . g ., see the embodiment depicted in employing them in the context of a hydroturbine .
FIGS. 34 and 35 ) because currents around 3 knots are the Generally, when considering design for a single selected
most commonly occurring currents in ocean currents , as current speed , such as , for example , 3 knots, the size of
well as in tidal currents and also in many river currents . hydroturbines according to the invention can be scaled up or
There are also examples of locations and /or circumstances in 55 down with typically only minor changes in the overall
which higher current speedsbetween about 5 kn and 7 kn are configuration . The main influencing factor of the choice of
commonly found , e .g., in areas where special geographic an " initial” hydrofoil shape, and then the further modifica
features are present such as, for example , rapid flowing tidal tion of that profile , is the flow speed of the water current in
currents or river currents, or even ocean currents in rare which the turbine is to be placed . In higher flow speeds such
instances, and then also in the case of towing one of the 60 as 6 kn , for example, the cross -section of the hydrofoil
hydroturbines behind a watercraft, typically a sailboat. In shapes are generally more slender and flatter (less camber on
order take into account these higher current speed situations, both sides of the hydrofoil) than they are in a profile design
the application also describes design modifications intended for a 3 kn current, where the cross -section of the hydrofoil
for embodiments designed for a 6 kn current, as being would be more curved and thicker (more camber on both
representative of and also exemplifying turbines intended 65 sides of the hydrofoil). This is generally illustrated in FIG .
for use in environments exhibiting these higher current flow 33 , where the differences in the respective cross - sections or
velocities. Therefore , the application describes embodi- profiles are clearly visible . In higher flow speeds, the chord
 US 10 ,294,913 B2
25 26
of the hydrofoil shape is also often increased . This is also The following is an example of results, from a solver
visible in FIG . 33, where in FIG . 33a the modified “ initial” program , of the CFD analysis conducted in 3 -D for an early
designs for the center hub and the accelerator shroud are design of an accelerator shroud and center hub, with the
more elongated when designed for use in a 6 kn current, than annular diffuser. With reference to FIG . 38A , there is
in the case of a similar configuration designed for use in a 5 depicted the pressure differential inside the turbine as a
3 kn current, as shown in FIG . 33b (which , however, is not result of flow acceleration , by means of showing stream
an “ initial” design , but rather a final design resulting from
lines. This is also used to determine if there is any turbulence
the second stage of the design process , as described below ).in the water flow that could reduce the efficiency. With
These modifications (carried out in the 3 - D modeling soft
ware ) are always done to create optimal lift and maximum 10 that resulttofromFIG the
reference . 38B , there are shown the pressure fields
flow streamlines shown in FIG . 38A .
flow speed acceleration . With the modified " initial” design These examples of the CFD analysis from an already
of FIG . 33a , which is somewhat intuitively designed in the partially optimized accelerator shroud and center hub , with
first step of the process , as discuss above , it is now possible
to move to the second stage of the design process ( discussed the annular diffuser added on, demonstrate a synergistic
below ) in which the modified “ initial” design is subjected to 15 effect of the elements together creating a much greater
the more quantitative optimization using CFD analysis . pressure differential.
The rotor blade shape is designed in the same fashion as In CFD , the program creates an elaborate mesh of poly
the center hub and accelerator shroud . Thus, a suitable hedral shapes to simulate the fluid volume and a very precise
" initial” hydrofoil shape is sketched or chosen from the shape of the turbine in the form of a mesh composed of
library , for the cross -section of the rotor blade, in accordance 20 millions of triangles. Afterwards, this newly created model
with the principles of the invention , and then modified is run through the solver of the program , which analyzes the
(utilizing fluid dynamics principles ) based upon the speed fluid /water flow (polyhedral bodies) over the turbine shape
with which it travels through the water, which speed is ( triangle mesh ) and shows the flow paths created by it. In
greater at the tip of the blade than at the root of the blade . this way, the final optimized shapes and configuration of the
Accordingly , the hydrofoil cross -section of the rotor blade, 25 components are arrived at by making changes and assessing
the length of chord , the thickness of the chord /profile and the the consequences of those changes based on the testing
incidence of the cross -section each preferably changes ,more feedback provided by CFD analysis , until a final optimum
preferably changes continuously, from the root of the blade combination of shapes is achieved .
out to the tip of the blade . During the first stage of the design Once all the hydrofoil shapes are optimized and shown to
process, as many modifications as possible are made by 30 work in harmony with one another, the potential energy
intuitively applying fluid dynamic considerations, to arrive extraction or electrical output is calculated . Here is an
at a modified “ initial" design . As is understood by persons exemplary result of the analysis of a particular blade shape
skilled in the art , this is typically done with the aid of developed during the early phase of the design , using CFD
software products designed to assist such design activities, to analyze pressure differential between both sides of the
such as, for example , programs called “ JavaProp , " 35 rotor blades (intrados and extrados) as they rotate through
“ QBlade ," and the like. ( The variations described here can the water ( to determine optimum shape and number of
generally be visualized by looking at the preferred final or blades). Reference here is to FIGS. 39 and 40 , which
" optimized ” embodiment illustrated in FIG . 34 , which illustrate the respective high and low pressure zones on the
depicts a rotor blade profile that is " optimized” (in the two sides of the rotor blades .
second stage ) for a 1.5 m diameter of the rotor blade section , 40 It will be appreciated that there are elements of trial and
for use in a 3 kn current. It is clearly visible how all the error involved not only in the first stage but also to some
parameters defining the hydrofoil shape of the blade and its degree in the second stage of the process . In the first stage ,
incidents change between the root and tip of the blade. ) the trial and error is informed not only by the skill of the
With reference to FIGS. 37A and 37B of the drawings, the artisan applying the principles taught in this application , but
former shows the flow acceleration in 2 - D velocity resulting 45 also by an intuitive application of the general principles of
from software analysis, whereas the latter is a related fluid dynamics , and more importantly by the quantitative
presentation showing flow acceleration in 2 - D pressure . test results provided by the various types of software that are
Both figures clearly show areas of enhanced acceleration applied to verify the effects of each modification made to the
resulting from the design characteristics according to the individual component designs. In the second stage , where
invention . 50 testing is done in 3 -Dimensions and for combinations of
Turning now to the second stage of the development components , there are obviously many opportunities for
process , those modified " initial” shapes created in the first changes that can be made ; however, optimization is rela
stage of design are then analyzed for their efficiency working tively straightforward at this point . From the CFD analysis ,
together in a turbine environment in creating the greatest areas evidencing lack of laminar flow and/ or turbulence can
pressure differentials and with the least turbulence to 55 be detected and then modified to remove these unwanted
achieve maximum water flow acceleration through a nozzle . flow effects. Typically , the target is considered to be what is
This is the “ optimization ” step , in which final, optimized theoretically believed to be the maximum possible improve
shapes are determined for each of the hydrofoil components . ment in results , for example , an increase in flow speed
For this analysis there is utilized what is called Computa - through the turbine of about three times the incoming ,
tional Fluid Dynamics (CFD ). As is well known, this testing 60 ambient current velocity . Alternatively, a target of a certain
is always done in a 3 -Dimensional framework . These simu - improvement in turbine power output, compared to known ,
lations can be done in any known CFD computer program , comparably sized turbine, can be chosen . When either or
such as one called " STAR CCM + ” which is one of the most both of these targets is/are approached or reached , optimi
advanced softwares in this field . This software enables the zation is considered to be achieved . For example , in FIGS .
designer of an intuitively created hydrofoil shape to analyze 65 34 and 35 the essential dimensions are shown for one
and optimize flow characteristics in a virtual environment preferred embodiment of a turbine according to the inven
prior to building prototypes for real life testing . tion , namely , a 1 .5 meter diameter turbine that has been
 US 10 ,294 ,913 B2
27 28
optimized for use in a current having a speed in the region confirmation of the functionality and efficiency of the design
of 3 knots as shown in the following Legends . for a given flow speed and a specific turbine size .
Legend for FIGS. 13 and 34 Site -Specific Design
Furthermore, this unique methodology of design can be
5 utilized to improve the extraction the maximum power out
72 degrees
Angle of incidence measured in Angle between axis of flow of any given naturally occurring water current by site
direction and axis of specific design . The first step of site - specific design consists
profile /chord length
74 Profile /chord length measured in Distance between leading of flow data collection of the characteristics at a specific
meters edge and trailing edge location or site . The flow speeds, the flow direction , the flow
75 Length of rotor blade Distance between root and tip 10 mass characteristics (volume ofwater flowing at any specific
of blade time) and the fluctuations in flow over a given period of time
76 Profile /chord thickness measured in Maximum distance between
meters intrados and extrados will be precisely measured and recorded with the aid of
78 Twist of blade measured in degrees Difference between incidence acoustic Doppler equipment. The second step is to assess ,
at root of the blade and
incidence at tip of blade
log and record the types and quantities of sea life and
15 wildlife in the area chosen for the installation site by
prolonged video recording, diving and logging of all the
Legend for FIG . 34 species and size of sea life. It is also necessary to log the type
and quantity of debris floating in the water. There after the
above stated design methodology can begin and then an
Angle of incidence at root of blade
Angle of incidence at tip of blade
35°
58°
20 optimized turbine for a specific site can be developed by first
slightly adjusting the hydrofoil shape of the accelerator
Profile /chord length at root of blade 0 . 181 m
Profile/chord length at tip of blade 0 .588 m shroud , the diffuser, the center hub and the rotor blades, and
Length of rotor blade 0 .498 m then adjusting the spacing of the bars on the wild life and
Profile /chord thickness at tip of blade
Profile / chord thickness at root of blade
0 .035 m
0 .107 m
debris excluder to the local needs . This will assure that no
Twist of blade measured in degrees 230 25 wildlife is harmed by the turbine, that the turbine does not
Flow direction get harmed by floating debris, and that the maximum amount
of energy /electricity can be extracted at the precise location .
All of the computer programs that have been mentioned
Legend for FIG . 35 in the foregoing description of the methodology of the
30 present invention are commercially available , and their
Diameter of diffuser entrance 2 .430 m
modes of use are likewise well known to persons skilled in
Diameter of accelerator shroud 2 .217 m this art.
entrance Thus, the Applicant has conceived of certain novel
Overall diameter of center hub 0 .665 m designs for hydrokinetic turbines , has furthermore taken
Profile /chord thickness of center hub 0 .084 m concepts , tools and information from a number of different
Length of accelerator shroud 1.651 m fields , and has employed and / or combined them in a novel
Length of diffuser 1 . 188 m
Length of center hub 1 . 131 m manner to design unidirectional hydrokinetic turbines that
Profile /chord thickness of accelerator 0 .260 m exhibit a significantly higher efficiency . This is due largely
shroud
Profile/chord thickness of diffuser 0 .158 m
to the synergistic interaction of multiple , novel turbine
Diameter of center hub exit 0 . 500 m 40 components that embody novel asymmetric hydrofoil char
Diameter of accelerator shroud exit 1 .917 m acteristics, which have been fine-tuned in a new way for the
94 Diameter of diffuser exit 2.694 m specific environment in which they are to be employed . The
" Novelty ofDesign Process” is evident because never before
Subsequently, the structural aspects of the design shape 45 have engineers and designers been able to achieve the highly
efficient results as demonstrated in connection with the
are analyzed in a Finite Element Analysis program , such as hydrokinetic turbines according to the present invention .
that called CD -Adapco FEA , Scan and Solve or similar. This These efficiencies
structural engineering is to confirm that the shapes of the usefully employed permit the turbines of the invention to be
in many contexts in which the current
profiles thathave been determined can actually be built with speed is too low to permit use of prior art turbines .
the requisite strength , e .g ., with composite materials. There 50 The design of these hydrokinetic turbines and/ or compo
are also several other software programs that can also be nents is unique because of the fact that no other design up
utilized along the way, such as SolidWorks, AutoCAD , with until the present has combined every possible hydrodynamic
mechanical event simulation , but they are minor contribu - advantage , let along in novel combinations (in component
tors to the design . selection , component design and interaction of these com
Once the shapes of the turbine are determined by intuitive 55 ponents together) to optimize the output of the turbine and
design /sketching, optimizing of shapes in 3 - D modeling and accelerate the flow of the water to extract more energy as is
CFD analysis , stage III of the development begins. This possible with the turbines of the present invention . Although
stage is the physical building of a fully functional prototype hydrodynamic principles are well known , the use of these
and testing in real-life conditions while monitoring and principles and the combination of novel designs and the
documenting all parameters of the design . This involves 60 effects of all the different elements used in this design ,
recording of rpm of the rotor section , electrical output of the especially the mutually beneficial and synergistic effects of
turbine unit, video recording of the flow characteristics these elements combined together, are new and inventive . As
through tufting of all surfaces ( similar to an airplane wing in demonstrated in this design , each and every element is
a wind tunnel). These tests are conducted at various different initially designed and then optimized for the flow speed and
flow speeds from 1 kn up to 6 kn utilizing various configu - 65 size of turbine , and therefore the end result is a hydrokinetic
rations of accelerator shroud shapes annular diffuser shapes turbine with much greater output and efficiency than other
and rotor section shapes . Ultimately this test results , in final designs proven up to present.
 US 10 ,294 ,913 B2
29 30
What is claimed is : an intrados facing radially toward the outside of the turbine ,
1. A unidirectional hydrokinetic turbine having a water said annular diffuser having a diameter greater than the
entrance end and a water exit end defining a single direction diameter of said accelerator shroud and being spaced apart
of water flow through the turbine, comprising : radially from the accelerator shroud and being positioned so
a generally cylindrical accelerator shroud that has a length 5 as to extend behind the main accelerator shroud , in the
extending from the water inlet end to the water exit end direction of Water flow through the turbine , in an axially
and comprises a radially inner wall and a radially outer overlapping relationship with the accelerator shroud .
wall spaced apart from the radially inner wall , to form 7 . The unidirectional hydrokinetic turbine as claimed in
a radial wall cross -section , wherein the radially inner claim 6 , wherein the accelerator shroud has a diameter at its
wall defines within its cylindrical cross -section a water 10 water exit end that is greater than the diameter at its water
flow area that contains therein structure that consists inlet end, and wherein the annular diffuser has a diameter at
essentially of an integral hydrokinetic force - generating its upstream end that is less than its diameter at its down
member that rotates as one unit in a single direction in stream end .
response to water flow in said single direction during 8 . The unidirectional hydrokinetic turbine as claimed in
force generation within the accelerator shroud , the 15 claim 1 , wherein the radial wall cross -section of the accel
integral force- generating member consisting essen erator shroud has an asymmetrical hydrofoil shape along the
tially of: length of the accelerator shroud , with an extrados facing
a center hub member having an open center surrounded radially toward the inside of the turbine and an intrados
by an inner wall that defines a water flow passage , and facing radially toward the outside of the turbine.
having a hydrofoil profile comprising a generally round 20 9 . The unidirectional hydrokinetic turbine as claimed in
profile formed by an outer wall and wherein the inner claim 8 , wherein the accelerator shroud has a forward
wall surrounding the open center and the outer wall portion upstream of the blades and a rearward portion
form an asymmetric hydrofoil profile , with the extrados downstream of the blades , and wherein the asymmetric
being toward the outside of the turbine and the intrados hydrofoil shape comprises a profile in which the radially
facing toward the center of the hub ; 25 outer surface comprises a forward convex portion and a
a plurality of blades , each blade having two edges and rearward concave portion , and the radially inner surface
extending radially outwardly from a radially inner base comprises a rearward convex portion and a forward portion ,
end thereof, at which base end each blade is mounted measured from the blades to the water entrance end that has
on said center hub member for rotation therewith to a shape, that is either straight or curved .
form a rotor assembly, said blades terminating at radi- 30 10 . The unidirectional hydrokinetic turbine as claimed in
ally outer blade tips ; and claim 9 , wherein the asymmetric hydrofoil profile is gener
a structural member connecting to the blades at the blade ally S - shaped and the forward portion , measured from the
tips and comprising a rotor outer ring to which the blades to the water entrance end , has a shape that is either
blade tips are attached and which has an outer circum - straight or concave.
ference that is configured for rotation within said 35 11 . The unidirectional hydrokinetic turbine as claimed in
accelerator shroud wall cross - section wherein said claim 1 , wherein the rotor blades have a generally straight
force -generating member is mounted at said structural axis extending radially from the center hub to their blade
member connected to the outer blade tips for support - tips.
ing the force - generating member for rotation , within 12 . A unidirectional hydrokinetic turbine having a water
the wall cross - section of said accelerator shroud , 40 entrance end and a water exit end defining a single direction
wherein said rotor blades have an asymmetrical hydro - of water flow through the turbine, comprising :
foil-shaped cross - sectional configuration , and wherein a generally cylindrical accelerator shroud that has a length
said blades have a profile thickness at their radially extending from the water inlet end to the water exit end
outer ends that is greater than the profile thickness at and comprises a radially inner wall and a radially outer
their radially inner ends and wherein the profile thick - 45 wall spaced apart from the radially inner wall, to form
ness is a chord thickness defined between each blades a radial wall cross -section , wherein the radially inner
pressure and suction sides. wall defines within its cylindrical cross - section a water
2 . The unidirectional hydrokinetic turbine as claimed in flow area , wherein the radial wall cross -section of the
claim 1 , wherein said blades have a chord length at their accelerator shroud has an asymmetrical hydrofoil shape
radially outer ends that is greater than the chord length at 50 along the length of the accelerator shroud with a curved
their radially inner ends . extrados facing radially toward the inside of the turbine
3 . The unidirectional hydrokinetic turbine as claimed in and a curved intrados facing radially toward the outside
claim 1 , wherein said center hub has a length that extends of the turbine ;
both forwardly and rearwardly a substantial distance past the a rotor assembly that is mounted for rotation as one unit
edges of said blades . 55 in a single direction in response to water flow in said
4 . The unidirectional hydrokinetic turbine as claimed in single direction within the accelerator shroud water
claim 3 , wherein said center hub extends from the blades flow area around center axis of the turbine that is
forwardly to a first point that is rearward of the water generally parallel to the direction ofwater flow through
entrance end of said accelerator shroud . the turbine, the rotor assembly comprising :
5 . The unidirectional hydrokinetic turbine as claimed in 60 (a ) as plurality of rotor blades, each blade having a
claim 4 , wherein said center hub extends a total distance of radially inner end and a radially outer end that termi
approximately 2/3 of the length of said accelerator shroud . nates in a blade tip , the rotor blades extending radially
6 . The unidirectional hydrokinetic turbine as claimed in outwardly with respect to an open center of the turbine
claim 1 , further comprising an annular diffuser comprising , that defines a water flow passage along said center axis ;
a generally cylindrical ring member that has a wall cross - 65 (b ) a rotor outer ring onto which the rotor blades are
section comprising an asymmetrical hydrofoil shape with an mounted for rotation with the outer ring by attachment
extrados facing radially toward the inside of the turbine and of the blade tips thereto , the outer ring having an outer
 US 10 ,294 ,913 B2
31 32
circumference that is configured for rotation within said a generally cylindrical accelerator shroud that has a length
accelerator shroud radial wall cross -section ; and extending from the water inlet end to the water exit end
( c ) at least one magnet or one stator winding mounted on and comprises a radially inner wall and a radially outer
the rotor outer ring or on at least one blade tip for wall spaced apart from the radially inner wall , to form
rotation with the rotor assembly ; and wherein said 5 a radial wall cross -section that comprises an asym
blades have a profile thickness at their radially outer metrical hydrofoil shape along the length of the accel
ends that is greater than the profile thickness at their erator shroud with an extrados facing radially toward
radially inner ends and wherein the profile thickness is the inside of the turbine and an intrados facing radially
a chord thickness defined between each blades pressure toward the outside of the turbine, and wherein the
and suction sides . 10 radially inner wall defines within its cylindrical cross
13 . The unidirectional hydrokinetic turbine as claimed in section a water flow area , said hydrofoil shape serving
claim 12 , wherein said rotor assembly further comprises a to accelerate the flow of water through the accelerator
center hub member and said rotor blades are attached to said shroud and to create a negative pressure field behind
hub member, wherein said blades have an asymmetrical the accelerator shroud , in the direction of water flow ;
hydrofoil- shaped cross - sectional configuration and wherein 15 a rotor assembly that is mounted for rotation as one unit
said hub member comprises a generally round profile mem in a single direction in response to water flow in said
ber having a hydrofoil profile and an open center. single direction within the main accelerator shroud
14 . The unidirectional hydrokinetic turbine as claimed in around an axis that is generally parallel to the direction
claim 13 , further comprising an annular diffuser comprising , of water flow through the turbine, the rotor assembly
a generally cylindrical ring member that has a wall cross - 20 comprising : (a ) a center hub member that consists
section comprising an asymmetrical hydrofoil shape with an essentially of a hub member that rotates with the rotor
extrados facing radially toward the inside of the turbine and assembly ; (b ) a plurality of rotor blades having radially
an intrados facing radially toward the outside of the turbine , inner ends attached to and extending radially outwardly
said annular diffuser having a diameter greater than the from the center hub member of the rotor assembly , and
diameter of said accelerator shroud and being positioned so 25 radially outer ends terminating at rotor blade tips,
as to extend behind the main accelerator shroud, in the which blades have an asymmetrical hydrofoil-shaped
direction of water flow through the turbine , in an overlap cross -sectional configuration ; and (c ) a rotor outer ring
ping relationship with the accelerator shroud . to which the blade tips are directly attached , and the
15 . The unidirectional hydrokinetic turbine as claimed in outer ring being configured to support the rotor assem
claim 13 , wherein the center hub member comprises a 30 bly within the asymmetrically shaped hydrofoil radial
profile member having an outer wall, and the open center is wall cross -section of the accelerator shroud and having
surrounded by an inner wall that defines a water flow an a radially outer circumference which is configured
passage , and wherein the inner wall and the outer wall form for rotation within said accelerator shroud wall cross
an asymmetric hydrofoil profile in axial cross -section, with section ; and ,
an extrados being toward the radial outside of the turbine 35 an annular diffuser comprising, a generally cylindrical
and intrados facing toward the center of the hub . ring member that has a wall cross -section comprising
16 . The unidirectional hydrokinetic turbine as claimed in an asymmetrical hydrofoil shape with an extrados
claim 15 , wherein the blades have a chord length at their facing radially toward the inside of the turbine and an
radially outer ends that is greater than the chord length at intrados facing radially toward the outside of the tur
their radially inner ends. 40 bine, said annular diffuser having a diameter greater
17 . The unidirectional hydrokinetic turbine as claimed in than the diameter of said accelerator shroud , being
claim 12 , wherein the accelerator shroud has a forward radially spaced from said accelerator shroud , and being
portion upstream of the blades and a rearward portion positioned behind the main accelerator shroud , in the
downstream of the blades, and wherein the hydrofoil shape direction of water flow through the turbine, whereby
comprises a profile in which the radially outer surface 45 the hydrofoil shape of the annular diffuser serves to
comprises a forward convex portion and a rearward concave accelerate the flow of water through the annular dif
portion , and the radially inner surface comprises a rearward fuser and to create a negative pressure field behind the
convex portion and a forward portion , measured from the annular diffuser, and in cooperation with the hydrofoil
blades to the water entrance end , that has a shape that is of said accelerator shroud , said rotor hub and said
either straight or curved . 50 blades to augment acceleration of water flow through
18 . The unidirectional hydrokinetic turbine as claimed in the main accelerator shroud at the location of the rotor
claim 17 , wherein the profile is generally S - shaped and the assembly ; and wherein said blades have a profile thick
radially inner surface of the forward portion of the profile is ness at their radially outer ends that is greater than the
straight or concave . profile thickness at their radially inner ends and
19 . A unidirectional hydrokinetic turbine having a water 55 wherein the profile thickness is a chord thickness
entrance end and a water exit end defining a single direction defined between each blades pressure and suction sides.
of water flow through the turbine, comprising: * * * * *