US011174829B2

( 12 ) United States Patent ( 10 ) Patent No.: US 11,174,829 B2

Schurtenberger (45 ) Date of Patent : Nov. 16 , 2021

( 54 ) HYDROELECTRIC /HYDROKINETIC (2013.01 ) ; F05B 2240/124 (2013.01 ) ; F05B

TURBINE AND METHODS FOR MAKING 2240/13 ( 2013.01 ) ; F05B 2240/33 ( 2013.01 ) ;
AND USING SAME F05B 2240/911 ( 2013.01 ) ; F05B 2240/93
( 71 ) Applicant: Walter Schurtenberger , Key West, FL ( 2013.01 ) ; F05B 2240/97 (2013.01 ) ; F05B
(US ) 2250/232 ( 2013.01 ) ; F05B 2250/73 ( 2013.01 ) ;
( Continued )
( 72 ) Inventor: Walter Schurtenberger, Key West, FL ( 58 ) Field of Classification Search
(US ) CPC FO3B 3/04 ; FO3B 3/06 ; FO3B 3/12 ; FO3B
3/121 ; FO3B 3/126 ; Y10T 137/794 ; Y10T
( 73 ) Assignee : HYDROKINETIC ENERGY CORP , 137/8085 ; Y10T 137/8122
Key West, FL (US ) See application file for complete search history .
( * ) Notice: Subject to any disclaimer, the term of this ( 56 ) References Cited
patent is extended or adjusted under 35 U.S. PATENT DOCUMENTS
U.S.C. 154 ( b ) by 90 days.
( 21 ) Appl. No .: 16 /403,472 3,986,787 A * 10/1976 Mouton , Jr. FO3B 17/061
415/7
May 3 , 2019 9,000,604 B2 * 4/2015 Sireli FO3B 17/061
(22 ) Filed : 290/54
( 65 ) Prior Publication Data (Continued )
US 2019/0264647 A1 Aug. 29 , 2019 Primary Examiner Woody A Lee , Jr.
Assistant Examiner — Brian O Peters
Related U.S. Application Data ( 57 ) ABSTRACT
( 63 ) Continuation of application No. 15 / 697,401 , filed on The application relates to unidirectional hydrokinetic tur
Sep. 6 , 2017 , now Pat . No. 10,294,913 , which is a bines having an improved flow acceleration system that uses
( Continued ) asymmetrical hydrofoil shapes on some or all of the key
( 51 ) Int . CI. components of the turbine . These components that may be
F03B 3/18 (2006.01 ) hydrofoil shaped include, e.g. , the rotor blades ( 34 ) , the
FO3B 3/12 (2006.01 ) center hub (36 ) , the rotor blade shroud ( 38 ) , the accelerator
shroud (20 ) , annular diffuser( s ) (40 ) , the wildlife and debris
( Continued ) excluder ( 10 , 18 ) and the tail rudder ( 60 ) . The fabrication
( 52 ) U.S. Cl . method designs various components to cooperate in opti
CPC FO3B 3/18 ( 2013.01 ) ; F03B 3/04 mizing the extraction of energy , while other components
(2013.01 ) ; F03B 3/121 (2013.01 ) ; F03B 3/126 reduce or eliminate turbulence that could negatively affect
(2013.01 ) ; FO3B 11/02 ( 2013.01 ) ; F03B other component( s ).
17/061 (2013.01 ) ; F05B 2220/7068 ( 2013.01 ) ;
F05B 2230/6102 (2013.01 ) ; F05B 2230/80 11 Claims , 24 Drawing Sheets

1
-30

26 26 -40

23 28
22
 US 11,174,829 B2
Page 2

Related U.S. Application Data

continuation of application No. PCT /US2016 /
017857 , filed on Feb. 12 , 2016 .
( 60 ) Provisional application No. 62 / 115,540 , filed on Feb.
12 , 2015 .
(51 ) Int. Ci.
FO3B 11/02 ( 2006.01 )
FO3B 17/06 ( 2006.01)
F03B 3/04 ( 2006.01 )
(52) U.S. CI.
CPC F05B 2260/84 ( 2013.01 ) ; YO2E 10/20
( 2013.01 ) ; YO2E 10/30 (2013.01 ) ; YO2P 70/50
(2015.11 )
( 56 ) References Cited
U.S. PATENT DOCUMENTS
9,488,155 B2 * 11/2016 Kehr HO2K 7/1823
10,030,520 B2 * 7/2018 Duchene FO1D 5/142
* cited by examiner
U.S. Patent Nov. 16 , 2021 Sheet 1 of 24 US 11,174,829 B2

40

52 50
10 52
20 30

FIG . 1

40
30 18
20
10

ASETI -60
50

FIG . 2
U.S. Patent Nov. 16 , 2021 Sheet 2 of 24 US 11,174,829 B2

10

30 40 18 60
20 50

FIG . 3

23
28 -40

22

FIG . 4
U.S. Patent Nov. 16 , 2021 Sheet 3 of 24 US 11,174,829 B2

00
21

1
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22
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1

23 ?
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20B FIG . 5A

20A 24
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FIG . 5B
U.S. Patent Nov. 16 , 2021 Sheet 4 of 24 US 11,174,829 B2

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U.S. Patent Nov. 16 , 2021 Sheet 5 of 24 US 11,174,829 B2

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U.S. Patent Nov. 16 , 2021 Sheet 6 of 24 US 11,174,829 B2

-26

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30

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FIG . 10
U.S. Patent Nov. 16 , 2021 Sheet 7 of 24 US 11,174,829 B2

ma

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FIG . 11

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U.S. Patent Nov. 16 , 2021 Sheet 8 of 24 US 11,174,829 B2

76 74

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FIG . 13
35
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FIG . 14
U.S. Patent Nov. 16 , 2021 Sheet 9 of 24 US 11,174,829 B2

33 35
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FIG . 16
U.S. Patent Nov. 16,2021 Sheet 10 of 24 US 11,174,829 B2
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U.S. Patent Nov.16,2021 Sheet 11 of 24 US 11,174,829 B2

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U.S. Patent Nov. 16 , 2021 Sheet 12 of 24 US 11,174,829 B2

51
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1. 3

50 51 53 51

52

FIG . 22
U.S. Patent Nov. 16 , 2021 Sheet 13 of 24 US 11,174,829 B2

56

55 55
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FIG , 24
U.S. Patent Nov. 16 , 2021 Sheet 14 of 24 US 11,174,829 B2
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FIG . 25

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VINNUNAN
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FIG . 26
U.S. Patent Nov. 16 , 2021 Sheet 15 of 24 US 11,174,829 B2

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FIG . 28
U.S. Patent Nov. 16 , 2021 Sheet 16 of 24 US 11,174,829 B2

58

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FIG . 29a
59

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FIG . 29b
U.S. Patent Nov. 16 , 2021 Sheet 17 of 24 US 11,174,829 B2
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U.S. Patent Nov. 16 , 2021 Sheet 18 of 24 US 11,174,829 B2

82 82

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U.S. Patent Nov. 16 , 2021 Sheet 19 of 24 US 11,174,829 B2

6kn Profile

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U.S. Patent Nov. 16 , 2021 Sheet 20 of 24 US 11,174,829 B2

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U.S. Patent Nov. 16 , 2021 Sheet 21 of 24 US 11,174,829 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
W,Paotwesr 250,000 -
200,000
150,000 -
100,000
50,000
0
2 3 4 5 6 7
Water Velocity, Knots
FIG . 36
U.S. Patent Nov. 16 , 2021 Sheet 22 of 24 US 11,174,829 B2

TR
High Velocity Zone
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
U.S. Patent Nov. 16 , 2021 Sheet 23 of 24 US 11,174,829 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 15.041 18.757

FIG . 38B
U.S. Patent Nov. 16 , 2021 Sheet 24 of 24 US 11,174,829 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 1.2312e +05 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 11,174,829 B2
1 2
HYDROELECTRIC /HYDROKINETIC artificially by building dams and creating reservoirs to
TURBINE AND METHODS FOR MAKING accumulate large masses of water that can be utilized on
AND USING SAME demand.
In 1882 the world's first hydroelectric power plant was on
CROSS - REFERENCE TO RELATED 5 the Fox River in Appleton Wis . By 1889 , 200 electrical
APPLICATIONS plants were built in the USA , and by 1920 , hydropower was
used for 25 % of US electrical generation , which usage by
The present application is a continuation of U.S. appli produced 1940 went up to 40% . Today only 6 to 8 % of the electricity
cation Ser. No. 15 / 697,401 , filed Sep. 6 , 2017 , now U.S. Pat. in the United States comes from hydropower.
No. 10,294,913 , which is a continuation of International 10 There
and costareadvantages
vast opportunities and bysignificant
to be gained replacingenvironmental
conventional
Application No. PCT /US1617857, filed Feb. 12 , 2016 , coal- fired power plants with hydroelectric installations .
which claims benefit of U.S. Provisional Application No. Older installations of hydroelectric power plants are mostly
62 / 115,540 , filed Feb. 12 , 2015 . situated inside dams or below dams using the pressure at the
BACKGROUND OF THE INVENTION 15 bottom of the dam to operate a water turbine that drives
electric generators.
The present invention relates to hydrokinetic turbines dynamicsSince World War I the field of science, today called fluid
designed for the purpose of generating electricity , and to precise and, hasfinitedeveloped tremendously and become a very
science which is used today in the design
methods for designing and using such turbines. It further 20 of modern hydrofoils. Hydrofoils ( as well as airfoils, also
relates to certain elements employed in hydrokinetic tur- part of fluid dynamics) are used for a large variety of
bines . The turbines according to the invention are intended purposes , including most designs in aeronautics , in motor
to be placed underwater, in a fixed , floating, anchored or vehicles, in watercraft, and in isolated elements employed in
towed configuration, in any location where the effective hydrokinetic turbines.
water current preferably flows with a minimum speed of 25 Hydrokinetic turbines can be divided up into different
about 0.25 m / s . The water flow or current may be of any type categories or types. For example, a turbine can either be
or source , although typically it is comprised of one or more bi - directional or unidirectional. In the former case , the
of the following types of water flow or current: turbine in defined such that it can be operated by a current
a) Fixed , floating or anchored in continuous water flow or that flows in both axial directions through the turbine, e.g. ,
current, as found , e.g. , in ocean currents, rivers or streams. 30 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 that may change a unidirectional turbine is driven only by the flow of water
direction periodically or irregularly, as fou e.g., in tidal in a single axial direction . From a hydrodynamic standpoint,
flow or seasonal flow . the design criteria to produce a bi - directional turbine are
c) Fixed, floating or anchored in mechanically or naturally 35 significantly more limited than in the case of a unidirectional
induced occurring currents that are created by, e.g. , filling turbine, i.e. , all design criteria that would produce an
9

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 categorizing hydrokinetic turbines resides
or other device or method to artificially or effectively create in their hub design , namely, whether the center hub is either
a flow through the device . 40 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 45 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 bearings between aa radially
in many different forms, including using flowing water and 50 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 55 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 60 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 ail 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 In an adaptation of the open center concept, a type of
currents that are most accessible and easiest to use for 65 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
 US 11,174,829 B2
3 4
to Sireli et al . , U.S. Pat . No. 7,471,009 to Davis et al . , both According to other preferred embodiments , the unidirec
of which relate to a unidirectional turbine design . Also see , tional hydrokinetic turbine further comprises an annular
U.S. Pat . No. 7,874,788 to Stothers et al . , and US 2010/ diffuser comprising a generally cylindrical ring member that
0007148 to Davis et al . , which relate to specially -config- has a wall cross -section , also preferably comprising an
ured, bi - directional hydrokinetic turbines that include the 5 asymmetrical hydrofoil shape, the armular diffuser having a
optional use of an open center hub or, in the latter, a bypass diameter greater than the diameter of the accelerator shroud
opening in the hub , as in related Davis et al . ’ 009 , noted and being positioned behind the main accelerator shroud , in
above ( see FIG . 7 of both ). the direction of water flow through the turbine, preferably in
Hydrokinetic power generation remains of great interest 10 an According
overlapping relationship .
to another aspect of the present invention,
and has gained growing importance along with solar power there is provided a unidirectional hydrokinetic turbine hav
and wind power. There is a need for significant effort to be ing a water entrance
made to design and build much more sophisticated and direction of water flowendthrough and a water exit end defining a
highly efficient hydrokinetic power - generating turbines; generally cylindrical acceleratortheshroud turbine, comprising a
that has a wall
however , because the process of refining turbine designs is 15 cross -section that comprises an asymmetrical
in many respects unpredictable and therefore time-consum shape, wherein the hydrofoil shape comprises a generally
hydrofoil
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 20 surface comprises a rearward convex portion and a forward
energy from a renewable source, with practically no envi- 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 25 direction of water flow through the turbine, the rotor assem
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 30 preferably with a generally round profile member having a
cylindrical accelerator shroud that has a wall cross - section 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- 35 asymmetric hydrofoil profile , with the extrados being
metrical hydrofoil profile ; and a plurality of blade members toward the outside of the turbine and the intrudes 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 40 attached and which has an outer circumference configured
includes a rotor outer ring to which the blade tips are for rotation within the accelerator shroud , in other preferred
attached and which has an outer circumference that is embodiments, the unidirectional hydrokinetic turbine farther
configured for rotation within foe accelerator shroud. Pref- comprises an annular diffuser comprising, a generally cylin
erably, the hub member comprises a generally round profile drical ring member that has a wall cross - section that also
member having an open center and wherein the wall mem- 45 comprises an asymmetrical hydrofoil shape, the annular
bers surrounding the open center form an asymmetric hydro- 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 of water flow through the
Also , the blades preferably have an asymmetrical hydrofoil- turbine, preferably in overlapping relationship .
shaped cross - sectional configuration, with the blades most 50 According to another aspect of the present invention,
preferably having a cord length at their radially outer ends there is provided a unidirectional hydrokinetic turbine hav
that is greater than the cord length at their radially inner ing a water entrance end and a water exit end defining a
ends, and a profile / cord thickness at their radially outer ends direction of water flow through the turbine, comprising a
that is greater than the profile thickness at their radially inner generally cylindrical accelerator shroud that has a wall
ends. It is most preferred that accelerator shroud has aa wall 55 cross -section that comprises an asymmetrical hydrofoil
cross -section that is also an asymmetrical shape. shape and defines within its cylindrical cross - section a flow
According to oilier 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 60 direction of water flow ; a rotor assembly that is mounted for
extending from the blades forwardly to a first point that is 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 aa wall cross - section com
center hub extends a total distance from about 50 to 80 % , 65 prising a hydrofoil shape; a plurality of rotor blades fixed to
more preferably from about 60 to 70 % and most preferably 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 ,
 US 11,174,829 B2
5 6
which blades have an asymmetrical hydrofoil - shaped cross- foil-shaped cross - section in order to reduce turbulence in tire
sectional configuration, and a rotor outer ring to which the water flowing across the ring and / or deflector rods.
blade tips are attached and having an outer circumference According to another aspect of the present invention,
which is configured for rotation within the accelerator there is provided a unidirectional hydrokinetic turbine hav
shroud: and an annular diffuser comprising, a generally 5 ing a water entrance end and a water exit end defining a
cylindrical ring member that has a wall cross - section com- direction of water flow through the turbine, comprising a
prising an asymmetrical hydrofoil shape . The annular dif- generally cylindrical accelerator shroud that has a wall
fuser has a diameter greater than the diameter of the accel- cross - section comprising a generally asymmetrical hydrofoil
erator shroud and is positioned behind the main accelerator shape, which serves to accelerate the flow of water through
shroud, in the direction of water flow through the turbine, 10 the main accelerator shroud and to create a negative pressure
preferably in overlapping relationship , whereby the hydro- field behind the accelerator shroud , in the direction of water
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 15 an asymmetrical hydrofoil profile, and a plurality of blade
shroud , the hydrofoil shaped rotor hub and the blades , to 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 20 the water entering the turbine to a flow velocity at the blade
radially outer ends that is greater than the chord length at members that is at least about twice the ambient flow
their radially inner ends and / or the blades have a profile / cord velocity, preferably at least about 21/2 times and most
thickness at their radially outer ends that is greater than the preferably at least about 3 times . Furthermore, the turbine is
profile /cord thickness at their radially inner ends . In other characterized by its ability to provide an increase in power
preferred embodiments, the center hub comprises a gener- 25 output, compared to conventional hydrokinetic turbines of
ally round profile member having an open center, wherein equal diameter, by a factor of at least about 25 % , preferably
the wall members surrounding the open center form a by at least about 50 % and most preferably by at least about
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 30 there is provided a shroud that is designed for use in a
a length that extends both forwardly and rearwardly a 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 35 cross -section comprising a generally asymmetrical hydrofoil
least as far as the water exit end of the accelerator shroud . 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, ml
most preferably about 23 of the length of the accelerator the inner surface comprises a rearward convex portion find
shroud. It may also extend rearwardly beyond the rear edge 40 a forward portion that has a shape that is either straight or
of the accelerator shroud . 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 the main 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 45 According to yet another aspect of the present invention,
generally cylindrical accelerator shroud section that defines 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- 50 cross -section that comprises an asymmetrical hydrofoil
bly comprising a plurality of rotor blades extending radially 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 55 extending radially outwardly from the center of the turbine
tapered Toward its forward /narrow end find comprises an 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 cord length
predetermined distance defines the maximum size of wild- 60 at their radially outer ends that is greater than the cord length
life or an object that can pass through the deflector. Prefer- at their radially inner ends , andf / r a profile /cord thickness at
ably, the wildlife and / or debris deflector member includes at their radially outer ends that is greater than the profile
its forward /narrow end aa ring member to which the deflector 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 65 hub member, preferably with a generally round profile
preferred embodiments, the ring member and /or at least 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
 US 11,174,829 B2
7 8
ably, the hub member comprises a generally round profile provide cooperation with the final hydrofoil shapes of the
member having an open center, with the wall members accelerator shroud , the rotor hub and the blades, to at least
surrounding the open center forming an asymmetric hydro- enhance, and preferably optimize acceleration of water flow
foil profile , with the extrados being toward the outside of the through tho accelerator shroud at the locution of the rotor
turbine and the intrados facing toward the center of the hub . 5 assembly.
According to still another aspect of the present invention , Further features and advantages of the present invention
there is provided a wildlife and / or debris deflector member will become apparent from the detailed description of pre
that is designed for use in a hydrokinetic turbine. The ferred embodiments that follows, when considered together
wildlife and / or debris deflector member is designed to be with the accompanying figures of drawing.
mounted at either end or both ends of a turbine. The deflector 10
comprises a generally conically -shaped structure which is BRIEF DESCRIPTION OF THE DRAWINGS
tapered toward one end and comprises an array of deflector
rods that run parallel to each other and are spaced essentially The following is a brief description of the drawings,
evenly at a pre -determined distance over their full- length which are presented for the purpose of illustrating the
with respect to one another, whereby the predetermined 15 disclosure of certain preferred embodiments of the invention
distance defines the maximum size of wildlife or an object set forth herein and not for the purpose of limiting the same .
that can pass through the deflector. Preferably, the wildlife
2
FIG . 1 is a three -dimensional front view of one embodi
and / or debris deflector member includes at its narrower end ment of a hydrokinetic turbine with support /mounting struc
a first ring member to which the deflector rods are attached ,
the first ring having a diameter no larger than the pre- 20 tureFIG
; . 2 is a three -dimensional rear view of the hydroki
determined distance . Similarly, the deflector preferably has netic turbine of FIG . 1 , with support /mounting structure;
at or near its wider end a second ring member to which the
deflector rods are attached . In other preferred embodiments, FIG . 3 is a cross - sectional side view of the hydrokinetic
at least some and preferably all of the deflector rods and / or
turbine of FIG . 1 , with support/ mounting structure ;
rings have a hydrofoil -shaped cross - section . 25 FIG . 4 is aa three -dimensional view of one embodiment of
In accordance with another aspect of the present inven- an accelerator shroud with annular diffuser;
tion, there is provided a method for designing a unidirec- FIG . 5A is a partial cross - sectional view of an S - shaped /
tional hydrokinetic turbine having a water entrance end and double -curved hydrofoil accelerator shroud, in an arrange
a water exit end defining a direction of water flow through ment as shown in FIG . 4 , with annular diffuser;
the turbine, comprising designing a generally cylindrical 30 FIG . 5B is a partial cross - sectional view of a non -S
accelerator shroud that has a wall cross - section that com shaped hydrofoil accelerator shroud , in an arrangement as
prises an initial asymmetrical hydrofoil shape and defines shown in FIG . 4 , with annular diffuser;
within its cylindrical cross - section a flow area , where the FIG . 6 is a partial cross - sectional view of another embodi
hydrofoil shape is selected based on fluid dynamics prin ment
ciples to serve to accelerate the flow of water through the 35 ers ofofsimilar
an accelerator shroud, with multiple annular diffus
diameters;
accelerator shroud and to create a negative pressure field FIG . 7 is a partial cross -sectional view of another embodi
behind the accelerator shroud , in the direction of water flow ; ment of an accelerator shroud , with multiple annular diffus
designing a rotor assembly that is mounted for rotation
within the accelerator shroud around an axis that is generally ers with different diameters;
parallel to the direction of water flow through the turbine, 40 FIG . 8 is a three - dimensional view of one embodiment of
the rotor assembly comprising ( i ) a generally elongated an entire turbine with central rotor section :
cylindrical center hub having and aa wall cross - section com FIG . 9 is a cross - sectional view the entire turbine of FIG .
prising an initial hydrofoil shape that is selected based on 8 , with central rotor section in place
fluid dynamics principles ; ( ii ) a plurality of rotor blades FIG . 9A is an isolated perspective view of the accelerator
fixed to and extending radially outwardly from the center 45 shroud, schematically showing the placement of coils
hub wall for rotation therewith and terminating at rotor tips , FIG . 10 is a three - dimensional view of the rotor section
which blades have an initial asymmetrical hydrofoil- shaped alone of the embodiment of FIG . 8 ;
cross - sectional configuration that is selected based on fluid FIG . 11 is a schematic side view of the rotor section of
dynamics principles; and (iii ) a rotor outer ring to which the FIG . 8 , showing one of the hydrofoil shaped rotor blades, the
blade tips are attached and having an outer circumference 50 rotor blade shroud and the hydrofoil shaped center hub ;
which is configured for rotation within the accelerator FIG . 12 is a perspective view of four rotor blades alone in
shroud; designing an annular diffuser comprising a generally the embodiment of FIG . 8 ;
cylindrical ring member that has a wall cross - section com- FIG . 12A is an isolate perspective view of a single
prising an initial asymmetrical hydrofoil shape that is exemplary rotor blade ;
selected based on fluid dynamics principles, wherein the 55 FIG . 13 is a cross - sectional view of one embodiment of a
annular diffuser bis a diameter greater than the diameter of rotor blade , illustrating certain preferred features, including
the accelerator shroud and is positioned behind the main the variable angle of attack , variable cord length , and
accelerator shroud, in the direction of water flow through the variable thickness of profile and twist;
turbine, preferably in overlapping relationship ; and modify- FIG . 14 is an isolated perspective view of a four rotor
ing the initial hydrofoil shapes of the annular accelerator, the 60 blade embodiment, with cross - sections of hydrofoil shapes
center hub, the rotor blades and the annular diffuser, in of the blades :
response to CFD testing/analysis of aa turbine design com- FIG . 15 is a perspective view of single rotor blade alone
prising such components , in such a way as to provide final with cross - sections of hydrofoil shapes ;
hydrofoil shapes for all of these components that (a ) at least FIG . 16 is a perspective view of one embodiment of a
enhance, and preferably optimize the ability to accelerate the 65 turbine with front and rear wildlife and debris excluders;
flow of water through the annular diffuser and to create a FIG . 17 is a cross - sectional view of the turbine of FIG . 16 ,
negative pressure field behind the annular diffuser, and ( b ) with front and rear wildlife and debris excluders ;
 US 11,174,829 B2
9 10
FIG . 18 is a perspective view of the turbine of FIG . 16 , FIGS . 37A and 37B illustrate 2 - D test results of CFD
with front and rear wildlife and debris excluders and utiliz- analysis of flow acceleration , in velocity and in pressure ,
ing a hydrofoil/teardrop shaped deflector bar to form the respectively, of an embodiment according to the invention .
excluders; FIGS . 38A and 38B illustrate CFD measurements, in
FIG . 18A is an isolated perspective view showing in detail 5 velocity streamlines and pressure fields, respectively, of an
the teardrop profile of FIG . 18 ; embodiment according to the invention .
FIG . 19 is an exploded perspective view schematically FIGS . 39 and 40 show pressure differential on the front of
showing all components in partial cross - section according to the blades and on the back of the blades , respectively, in
one embodiment of the invention ; CFD testing
FIG . 20 is an exploded view of the turbine of FIG . 19 , 10
showing all components in a schematic side view and DETAILED DESCRIPTION OF PREFERRED
partially in section ; EMBODIMENTS OF THE INVENTION
FIG . 21 is a perspective view of one embodiment of a
piling -mounted hydrokinetic turbine mounted on a pivoting The devices according to the invention are characterized
pedestal; 15 by a unique flow acceleration system and other unique
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 20 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 aa 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 ; 25 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 30 They are preferably equipped with wildlife and debris
hydrokinetic turbine installed between two ocean barges; excluder, a safe passage or way through for small marine 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 35 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 40 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 aa vessel ; 45 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 50 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 55 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 60 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 65 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,
 US 11,174,829 B2
11 12
such as the rotor blades or the accelerator shroud , can the turbine . This means that, for example, if this device was
advantageously be hydrofoil shaped in order to optimize the placed in aa 3 kn current the flow speed the through the rotor
extraction of energy , while other components such as the section of this device would be up to 9 kn . The very
wildlife and debris excluders may be hydrofoil shaped in significant advantages of this increased current to the pro
order to reduce or eliminate turbulence that could negatively 5 duction of hydroelectric power are clearly apparent.
affect another component or components. The effects of each individual part as well as the effects of
The hydrodynamic principles that apply to this design are interaction /cooperation and relation of the parts to one
valid for any size to which this hydrokinetic turbine is scaled another are described in detail below, in connection with
and whatever the flow speed of the water is . With appro- several exemplary embodiments of the invention , with ref
priate change in the shapes of these hydrofoil shaped com- 10 erence to the accompanying Figures of drawing.
ponents, tins hydrokinetic turbine can be adapted and opti
mized to the flow conditions of a specific site and to the size LIST OF PARTS
of turbine required. The changes to the hydrofoil shapes are
advantageously made to one or more of the rotor blades , the 10 forward wildlife and debris excluder
accelerator shroud, the center hub and / or the annular dif- 15 12 forward ring of excluder for attachment of the deflector
fuser. The changes, which in some cases can be relatively rods
small and may consist in increasing or decreasing the cord 14 hydrofoil shaped deflector rods
length and / or the cord thickness of some hydrofoils and / or 15 distance between deflector rods
changing the angle of attack / incidence of the hydrofoils 16 rear /aft ring of the excluder for attachment of the deflec
according to the speed of the water flow and the required 20 tor rods
size of the turbine. This means that the design of specific 18 rear /aft wildlife and debris excluder
embodiments according to the invention may change rela- 20 complete accelerator shroud
tively or even very little in appearance, but will work exactly 20A radially inner wall of accelerator shroud defining inner
the same way regardless of the size of the turbine or speed edge of axial cross -section
of the water flow , as long as the proportions in size and 25 20B radially outer wall of accelerator shroud defining outer
position of the components relative to each other and the edge of axial cross -section .
position between the individual parts are maintained and 21 S - shaped /double -curve of hydrofoil shape accelerator
remain unchanged or very similar. shroud cross - section
The output of the turbine will increase in proportion with 22 entrance duct/ forward fairing of accelerator shroud
the surface area of the rotor blades ; this means that the 30 23 stator housing center section of the accelerator shroud
driving force that determines how many kilowatts or mega- 24 non - S - shaped hydrofoil shape accelerator shroud cross
watts a turbine produces is not in proportion to its diameter, section
but in proportion of the surface area of the rotor blades 25 metallic windings of the stator
exposed to the water current. The output of a turbine 26 9 roller /ball bearings (3 thrust bearings forward , 3 thrust
increases by the square of the diameter; in other words a 35 bearings aft, 3 alignment bearings )
turbine that is twice as big in diameter will put out four times 28 aft fairing /aft section of accelerator shroud
the electrical power. This property of the design makes the 29 feather edge of accelerator shroud
turbine scalable to almost any size that is practical and 30 complete main rotor section with hydrofoil shaped
usable in a body of water with changes to the hydrofoil blades , rotor blade shroud with recess for permanent
shapes which are often relatively minor changes. 40 magnet installation, hydrofoil shaped center hub
The design and the use of these particular shapes of the 32 ring of permanent magnets mounted in recess on rotor
hydrofoil parts do not only eliminate the tip vortex of the section
rotor blades but also accelerate water flow through the rotor 33 tip of rotor blades
section of the turbine due to the fact that the accelerator 34 hydrofoil shaped rotor blades
shroud, in combination with the annular diffuser, creates an 45 35 cross - sections of hydrofoil shapes of rotor blades
area of low pressure at the exit of or behind the turbine that 36 hydrofoil shaped center hub
is preferably further amplified by the hydrofoil shaped 37 open center of main rotor section
center hub . These components together create a synergy to 38 rotor blade shroud with recess for permanent magnet
increase the water flow even more . The water flow that is installation
already slightly accelerated at the entrance of the turbines 50 39 root of rotor blades
through the funneling effect of the entrance duct is further 40 annular diffuser with hydrofoil shaped cross -section
accelerated by this low -pressure area behind the turbine that 42 2nd annular diffuser
creates a suction to pull the water through the rotor section 44 3rd annular diffuser
from behind at even greater speed . In the case of the 50 tubular support structure for various mounting purposes
preferred use of the hydrofoil shape of the parts, the designs 55 51 hydrofoil shaped attachment rods between turbine com
according to the invention achieve a very large increase in ponents and support structure
flow speed through the rotor section of the turbine where the 52 support piling for pivoting
hydrofoil shaped blades are positioned . No other known 53 waterproof plug for removal, rings and brushes for
hydrokinetic turbine design has achieved this degree of flow pivoting inside piling
acceleration . 60 54 floating raft or ocean barge
The flow acceleration created by the unique shapes and 55 support structure for rotating on a raft/barge installation
combination of all the hydrodynamic elements remains the 56 cranes for turbine rotation on raft/barge installation
same at any size of turbine. Computational fluid dynamic 58 submersible raft for buoyant installation
analysis of the designs of hydrokinetic turbines according to 59 seabed mooring or screw - type anchor
the invention has proven that they accelerate the flow speed 65 60 turbine tail rudder to orient turbine into the direction of
through the rotor section to as much as about three times the the water flow
speed of the ambient flow speed surrounding the outside of 62 winglets attached the turbine for towing installation
 US 11,174,829 B2
13 14
64 fixed tether and mooring for barge / raft mounted instal- The entrance duct (22 ) serves to funnel the water flow into
lation or buoyant installation the rotor section ( 30 ) and to lead the water flow onto and
66 rolling tether to submerge turbine by shortening or over the stator housing (24 ) on the outside of the accelerator
lengthening for surfacing shroud and over the rotor blade shroud (38 ) on the inside .
72 incidence /angle of attack of hydrofoil blade 5 This stator housing exterior surface and the rotor blade
74 cord of hydrofoil /length of cord shroud interior surface are part of the overall shape of the
75 length of rotor blade accelerator shroud . The entrance duct also contains the
76 thickness of hydrofoil cross - section / shape forward thrust bearings that guide the rotor section during
78 twist of rotor blade / change of incidence operation .
80 solid /bulbous center hub 10 The stator housing (24 ) contains all the metallic , prefer
82 hydrofoil shaped vanes to support that position solid generator, as well (as25 the
ably copper , coils ) that comprise the stator of the annular
conventional electrical wiring ( not
center hub shown ) to convey the electrical energy generated out of the
83 diameter of diffuser entrance turbine . The stator housing also contains the rotational
84 diameter of accelerator shroud entrance 15 roller /ball hearings ( or other bearings or low friction poly
85 overall diameter of center hub mer bushings ) (26 ) on which the rotor section rotates .
86 profile /cord thickness of center hub The exterior surface of the rotor blade shroud (38 ) forms
87 length of accelerator shroud part of the accelerator shroud but is a separate part that is
88 length of diffuser attached to the rotor blade tips ( 33 ) and rotates with the main
89 length of center hub 20 rotor inside the accelerator shroud . It is described in more
90 profile /cord thickness of accelerator shroud detail below .
91 profile /cord thickness of diffuser The aft fairing (28 ) located behind the stator housing (24 )
92 diameter of center hub exit and rotor blade shroud ( 38 ) leads the water flow to the exit
93 diameter of accelerator shroud exit of the accelerator shroud (20 ) and preferably has a feather
94 diameter of diffuser exit 25 edge (29 ) on the back end to avoid creating any turbulence
95 flow direction or drag. The aft fairing also contains the aft/ rearward thrust
The invention is preferably composed of four main com- bearings ( 26 ) ( FIG . 9 ) against which the rotor section is
ponents, a ) a flow accelerator shroud, b ) an optional annular pushed while rotating.
diffuser following the flow accelerator shroud , c ) a main The annular diffuser (40 ) is also preferably an asymmetri
rotor which is built into the accelerator shroud but is a 30 cal hydrofoil shaped ring and preferably has a greater
separate part, and d) one or more optional wildlife /debris diameter than the accelerator shroud (20 ) . The annular
excluders. Some of these components typically comprise diffuser ( 40 ) is located behind the accelerator shroud and
several different sub - parts that are assembled be one part preferably overlaps somewhat over the aft end of the accel
of the turbine . Additional features and advantages are erator shroud (20 ) . It works in a manner very similar to the
described below. These parts and features cooperative with 35 accelerator shroud , further increasing the negative pressure
and have an effect on one another in ways that are also field behind the turbine. Because of the cooperation and
described below to produce the improved operation of the resulting synergistic effect of the accelerator shroud and the
turbines according to the invention . annular diffuser, there is a greater augmentation of flow
The Flow Accelerator Shroud with the Annular Diffuser speed through the rotor section . Generally, at a position
Referring now to FIGS . 1-5 , 8 and 19 , the flow accelerator 40 relatively closely (e.g. , from about 4 to 6 inches ) behind the
shroud (20 ) is an important part that embodies the most trailing edge of the ( final) annular diffuser, which is prefer
complex hydrofoil shape. As used in the designs of this ably a feather edge, the rear wildlife and debris excluder is
invention , it preferably has an asymmetrical hydrofoil shape attached . There may be some instances in which it may be
and most preferably an S -shaped /double -curved hydrofoil advantageous, e.g. , specific water flow conditions, to
shape (FIG . 5a , 21 ) , or in other words a generally S - shaped 45 employ one or more annular diffusers , such as second
double -curved configuration (FIG . 9 ) , to create a negative annular diffuser ( 42 ) and maybe even a third annular diffuser
pressure field behind the shroud in order to accelerate the (44 ) , positioned one behind the other. ( FIGS . 6-7)
water flow through the rotor section (30 ) of the turbine . The The Rotor Assembly
cross -section of the wall of the accelerator shroud may also Turning now to FIGS . 10-15 , the hydrokinetic turbines of
be a hydrofoil shape that is not an S - shaped double -curved , 50 the invention preferably have an open center (37 ) . In part,
but resembles much more conventional hydrofoil shapes this is advantageous in the designs of the present invention
( FIG . 55 , 24 ) . The axial cross - sectional profile of the accel- because of the low speed that the blades travel through the
erator shroud is defined between radially inner wall 22A and water near the center of the rotor section and therefore do not
radially outwardly spaced outer wall 20B , as shown in FIG . create sufficient lift or enough energy worth extracting.
56. The accelerator shroud accelerates the flow of the water 55 Actually, the center portion generally has a negative effect
on the inside of the turbine in comparison to the ambient on the rotor due to the extra drag it creates by a larger wetted
flow speed around outside the accelerator shroud . The surface and additional weight needing to be moved through
accelerator shroud is preferably composed of four pieces : the water . The extremities of the rotor blades ( 34 ) travel
entrance duct ( 22 ) , the stator housing ( 24 ) , the rotor blade through the water at a higher speed and therefore create
shroud (38 ) (FIG . 10 ) and the aft fairing (28 ). These four 60 substantially more lift and allow substantially greater energy
components together preferably form a single shape , which extraction . Depending on the size of the turbine, the flow
is preferably the asymmetrical hydrofoil of the accelerator speed at a location of the installation and other site - specific
shroud , which in certain preferred embodiments has the needs , the ratio between open center and blade and hub size
S - shaped /double - curved hydrofoil shape. All four pieces are can be anywhere from about 40 % blade : 60 % open space , to
preferably faired together to form a perfectly smooth surface 65 about 80 % blade : 20% open space . Turbines according to the
both inside and outside , over which the water flows without invention advantageously use the major portion of the
creating any significant turbulence . overall diameter along the perimeter of the rotor section to
 US 11,174,829 B2
15 16
produce lift, typically more titan about 60% and more the purpose of optimizing the angle of attack or incidence of
preferably approximately 2/3 of the diameter. This leaves the the blade traveling through the water . It is preferred to use
remaining minor portion, e.g. , in a preferred embodiment an optimum angle which is determined by the rpm of the
approximately 1/3 of the overall diameter in the center open rotor to produce a laminar or at least a near laminar flow of
( 37 ) . Eliminating the center section of the rotor reduces the 5 the water over the blade surface . If this flow is turbulent or
overall weight of the rotor and also reduces the wetted significantly non - laminar, the hydrofoil creates less lift, and
surface area and drag that a solid profile section would therefore less energy can be extracted . The tip of the blade
create . Therefore the designs of this invention create a more travels through the water faster than the root of the blade ,
efficient rotor section that uses a smaller blade area with less due to the fact that it travels a longer distance to complete
weight, with less wetted area and less drag, which can rotate 10 one rpm . Therefore the incidence of the blade advanta
at higher rpm rates and allow more energy to be extracted . geously decreases gradually from the root ( 39 ) of the blade
There is also a secondary effect that is of further benefit to to the tip ( 33 ) of the blade , in order to be at the optimal
the wildlife and debris excluder that is described below . angle. This change in angle is called the twist (78 ) of the
The center hub (36 , 80 ) , that is preferably annular find blade. The twist is preferably designed to create a rotor blade
surrounds the preferably open center (37 ) , is also used for 15 maximum lift at every cross - section and therefore to
attaching the rotor blade roots (39 ) . ( FIGS . 11-12 and 31 ) increase the efficiency and the power extraction .
The center hub ( 80 ) that is solid preferably has a symmetri- In order for hydrofoil shapes according to the invention to
cal hydrofoil shape, whereas the center hub 36 with open be optimal while they travel through the water at different
center preferably has an asymmetrical hydrofoil shape , with speeds , they preferably have different lengths of cord (74 )
the extrados being toward the outside of the turbine and the 20 and different thicknesses of profile / cord ( 76 ). Preferably, the
intrados facing toward the center of the hub . The lift created thickness ( 76 ) of the blade increases and / or the cord length
by the center hub helps further increase the negative pres- (74 ) increases from the root of the blade toward the tip of the
sure field behind the turbine created by the accelerator blade, in order to increase the surface area where the blade
shroud ( 20 ) and the annular diffuser ( 40 ) . This effect travels though the water with higher speed and creates the
increases the acceleration of the water flow through the rotor 25 greatest amount of lift. Thus, the blades most preferably
blade section and contributes to the synergistic effect and increase in both size and thickness as they extend radially
resultant higher power generation. from the hub . These increases in cord length and thickness
The rotor blade shroud (38 ) (also called the outer ring of result in higher efficiency and greater power extraction .
the main rotor) is where the extremities /tips ( 33 ) of the The rotor blades hydrofoil shape (35 ) , the length of cord
blades (34 ) are attached . ( FIG . 10 ) This rotor blade shroud 30 (74 ) , the thickness of profile / cord ( 76 ) , the degree of inci
( 38 ) forms a pan of the hydrofoil shape of the accelerator dence ( 72 ) , and the twist (78 ) of each rotor blade , and the
shroud ( 20 ) . It is a separate element from the accelerator number of blades can advantageously be varied for each
shroud allowing it rotate with the rotor blades (34 ) , but the application, in order to adapt te - specific flow conditions
surface of the rotor blade shroud is preferably perfectly in of the water and other locational needs .
line with the inside surface of the accelerator shroud ( 20 ) to 35 The Wildlife and Debris Excluder ( s )
create one smooth curve of both inside surfaces, accelerator Referring now primarily to FIGS . 16-18 , a hydrokinetic
shroud and rotor blade shroud . The outside surface of the turbine that produces energy from aa renewable source with
rotor blade shroud, which faces the stator housing (24 ) zero carbon emissions should be environmentally friendly
interior surface, is preferably recessed into the accelerator not only to the natural resources and to the atmosphere, but
shroud and has a flat surface where the permanent magnets 40 also to marine and wildlife. This invention deflects and
( 32 ) are located which rotate past the copper coils ( 25 ) of the keeps any marine life and floating or submerged debris
stator to produce the electrical energy. The rotor blade above a specified size out of the hydrokinetic turbine’s rotor
shroud (38 ) also eliminates tip vortex and reduces drag and of the invention . The size of marine life or debris that cannot
turbulence , resulting in higher efficiency and greater energy enter the nozzle section of the turbine is specified by the
extraction . 45 spacing distance ( 15 ) of the deflector rods ( 14 ) of the
Referring now to FIGS . 11-15 , the efficiency of the rotor forward and rear excluder. In this invention the deflector
blades (34 ) is increased by preferably using an asymmetrical rods, by design , run parallel to each other and are evenly
hydrofoil shape , which is also preferably optimized, as spaced over their full- length to ensure that no distance
explained below . This shape, also called the cord or cross- between the rods ( 15 ) is greater in one place than in another.
section ( 35 ) of the hydrofoil, results in an increase of the 50 The distance of the spacing ( 15 ) is determined by the size
efficiency of each blade , reduces it in size and decreases the and the species of marine wild life as well as the size of
number of blades relative to other designs. A smaller rotor debris encountered to be excluded and to adapt to locational
blade (34 ) has less wetted area , thus producing less drag. needs of specific sites of operation . It will prevent any sea
The amount of lift a hydrofoil shape generates is determined life such as fish , turtles, sea mammals and even divers that
by the shape of cord / cross - section ( 35 ) (FIG . 15 ) , the length 55 are larger than the space ( 15 ) between the deflector rods ( 14 )
of cord ( 74 ) and the thickness of cord ( 76 ) of the hydrofoil. from entering into the rotor section of the hydrokinetic
( FIG . 13 ) In designs according to the invention , one or both , turbine from the front as well as from the back when a rear
the length of cord ( 74 ) and / or the thickness of cord (76 ) excluder is also employed.
preferably change between the blade root ( 39 ) and the blade The present designs contrast with other previously known
tip (33 ) . This optimizes the lift created by the hydrofoil 60 designs , ( see , e.g. , (U.S. Pat . No. 3,986,787 , US 2010/
shape in relation to the speed it travels through the water. 0007148 A1 , and U.S. D 614,560 ) which are characterized
The number of blades put into the rotor section of designs by deflector rods that are non parallel, such that the openings
according to the invention may vary depending on the size between the rods become bigger /wider towards one end of
of the turbine and the flow speed of the water in a particular the excluder, thus not limiting the entry of marine life or
application . 65 debris to a finite size . Some other prior art devices are
The angle /incidence (72 ) ( FIG . 13 ) at which the rotor designed as concentric circular deflector rods ( see , e.g. , U.S.
blades are installed is also a variable that can be adjusted for D 304,322 and U.S. Pat. No.5,411,224 ) which define aa finite
 US 11,174,829 B2
17 18
size of opening , but such configurations do not effectively current or also in the case of no current as for example
shed off all wildlife and debris like the deflector rods during the change from an incoming to an outgoing tide . The
according to the present invention, which are aligned deflector rods of the excluder are spaced to the same
obliquely with respect to the flow direction . In the concentric specified distance ( 15 ) as the forward wildlife and debris
design , wildlife or debris can easily become lodged between 5 excluder to prevent any wildlife or debris larger than the
the rings . In the designs of the invention, the exact size of specified distance from entering into the rotor section . Ail
marine life or debris to be excluded can advantageously be the deflector rods ( 14 ) of both of the excluders preferably
selectively predetermined by the distance ( 15 ) chosen have a hydrofoil shaped cross - section , to minimize the
between the deflector rods ( 14 ) . creation of turbulence and vortices that would negatively
Ocean currents and river currents contain floating debris 10 affect hydrofoil shapes that may be present on one or more
of many sorts . This debris may be floating at the surface or of the other components, such as , the rotor blades, the
submerged at different depths. Therefore, it is preferred to accelerator shroud, the annular diffusers, and / or the center
keep such debris out of the rotor section of the hydrokinetic hub .
turbine to the greatest extent possible , in order to prevent The smaller sea life that can pass through the spacing ( 15 )
damage to the turbine and to ensure continuous and unin- 15 of the deflector rods is advantageously provided a secondary
terrupted electrical output. The designs according to the path for safe passage through the cylindrical center hub (36 )
invention effectively deflect and keep out any debris above having an open center (37 ) in the majority of the depicted
the specified size ( 15 ) of the spacing of the deflector rods. turbine embodiments. The open center of the rotor section is
The hydrokinetic turbines according to the invention described above . Because the water flow speed in the center
preferably have two wildlife and debris excluders , one ( 10 ) 20 hub is faster than outside where the blades are situated ,
in front at the entrance (22 ) of the turbine and one ( 18 ) smaller sea life will be aspirated through that opening and
behind at the exit of the turbine . The front wildlife and debris can exit unharmed . The diameter of the open center may
excluder ( 10 ) is located in front of the turbine protecting the vary widely, without materially affecting the performance of
entrance (22 ) of the accelerator shroud (20 ) , and is attached the turbine . The optimum diameter can be calculated for
to the from end of the accelerator shroud as well as prefer- 25 each application, and in certain preferred embodiments is
ably to the support structure (50 , 52 ) of the turbine . The typically approximately 1/3 of the overall diameter of the
deflector rods ( 14 ) of the excluder may be made of metal, rotor section . The accelerated flow of the water through the
fiberglass or synthetic materials with different diameters open center ( 37) serves to safely convey small wildlife and
depending on the turbine size ; from about 1/4 inch on a small small debris through the inside of the turbine .
turbine and up to about 2 inches on very large units . The 30 No matter which installation method is chosen , the tur
deflector rods are preferably hydrofoil/ teardrop ( 14 ) shaped bines according to the invention are preferably automatically
in cross -section ( FIG . 18 ) with the blunt end pointing into self-orienting, meaning that they will always point exactly
the water flow and the sharp ends being the trailing edge . into the direction from which the water flow is coming. This
This configuration serves to avoid turbulence in the water is preferably achieved by the installation behind the turbine
flow that could disturb the efficiency of one or more other 35 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 coming, so that the water passing over the hydrofoil shaped
of the front excluder ( 14 ) form a generally cone - like shape . 40 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 flow of the water.
attached to a large ring ( 16 ) which is preferably greater 45 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 hydrodynamic effects , which , when combined together,
environmental needs . The front excluder is preferably posi- 50 result in aa 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 the Venturi /Bernoulli effect much better due to their unidi
cone - like shaped in order to shed off and divert any wildlife , 55 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 asymmetrical hydrofoil
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 The annular generator design preferably has magnets (32 )
the trailing edge of the ( final) annular diffuser. The rear 60 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 hydraulic systems to mechanically extract and convey the
preferred configuration is a generally planar one . The rear 65 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
 US 11,174,829 B2
19 20
annular generator, the invention minimizes these friction / behind the turbine than they would create individually or
transmission losses and creates a more efficient turbine or separately. In other words the effect of the plurality of
generator. The electrical energy generated directly inside the elements together is greater than the sum of the plural
turbine is transmitted through electrical wires (not shown) elements individually. This synergistic effect creates a
eliminating friction / transmission and power losses . The 5 greater acceleration of the flow through the rotor section
energy produced is then transmitted for conditioning to an where the asymmetrical hydrofoil shaped blades take greater
inverter / transformer that typically is located outside the advantage and are able to rotate at higher speed or RPM .
turbine, wherever deemed practical . The preferred design These
according to the present invention also eliminates the need mutuallycombined effects result in a synergistic effect that is
beneficial and that results in much higher effi
to have center bearings, which thereby eliminates the need 10 ciency that allows greater energy extraction thanks to this
for any fixed structure whatsoever (e.g. , shaft or hub) located “ Flow Acceleration Technology ” developed by the inventor.
within the flow area through the turbine. The absence of any
fixed structure furthermore means that no struts or other preferred embodiment, the presencetable
With reference to FIG . 36 , the
of
shows how , for one
the hydrofoil shaped
elements are needed to support that fixed structure.
The accelerator shroud (20 ), the annular diffuser (40) , the 15 accelerator shroud results in an exponential acceleration of
hydrofoil shaped center hub (36 , 80 ) and the rotor blades the flow velocity through the nozzle section , compared to the
( 34 ) of this turbine are preferably constructed of composite ambient flow speed .
building materials, such as , e.g. , carbon fiber, aramid fiber, The data represented in FIG . 36 illustrates the difference
fiberglass or similar in either solid fiber and resin or over in power output with increased ambient current velocity for
structural foam core material or honeycomb core material. 20 between 2 different designs of hydrokinetic turbines with a
Some parts such as the stator housing are preferably hollow 1.5 meter diameter rotor. The line with squares represents a
to accommodate the copper coils ( 25 ) of the stator. Other hydrokinetic turbine that simply has a hub and 3 blades, with
parts such as the entrance duct (22 ) , the aft fairing (28 ) of the no shroud that all (which is the most common use designs
accelerator shroud (20 ) and the annular diffuser (40 ) may in used in hydrokinetic turbines worldwide ). The line with
some preferred embodiments be solid or sandwich construc- 25 triangles demonstrates the output of this invention that
tion and remain hollow on the inside , with the option to be utilizes hydrofoil shaped accelerator shroud, annular diffuser
selectively filled with water when submerged. With the and open center hub . This is the same relationship for the
appropriate ( for the water depth ) structural bracing on the same rotor assembly contained within an accelerator shroud
inside of the hollow parts, they will be able to withstand the having a hydrofoil shape similar to that depicted in FIG . 35 .
water pressure of being submerged. In the case of sandwich 30 It is seen that the increase in power is according to an
construction, these composite materials utilized fire natu
rally buoyant and will keep the turbine floating. Although exponential power on the order of 3. It can also be seen that,
in the lower range of current velocities , ( e.g. , around 3 kn
composite materials are ideally suited for the construction of which
this hydrokinetic turbine, the device may also be built of turbinesrepresents the vast majority of applications for hydro
steel , aluminum , titanium or other metal alloys deemed 35 sensitive to changes ) , inthecurrent
of this type comparative relationship less
suitable for a specific application . The overall buoyancy of common range of operation, it isspeed . Therefore, in this
especially important to
this turbine will mostly be positive and may use ballast to
keep it submerged. The turbine may also be submerged by optimize the design of the shroud member ( and other
allowing hollow compartments to be filled with water. The components and relationships ), in order to maximize the
installation of an appropriate amount of ballast or water 40 relative increase in power output.
filling of certain compartments will allow the overall buoy- Another way to demonstrate the increased efficiency of
ancy of the turbine to be controlled to selectively make the the turbines of this invention is in a comparison to other
turbine become either positively buoyant, neutrally buoyant highly efficient commercially available turbines. One of the
or negatively buoyant, for different applications . most successful hydrokinetic turbine manufacturers and
The preferred self - orienting feature of the device allows 45 installers in the world has recently developed a new design
this turbine to be aa unidirectional flow turbine . In a unidi- of hydrokinetic turbine which it claims is their most effi
rectional turbine, the existence of a water flow that is always cient. It is a bidirectional turbine that has a 16 m diameter
coming from the front of the turbine allows the use of rotor section with an exterior shroud and a open center hub
asymmetrical or unidirectional hydrofoil shapes in the which is claimed to be able to produce 2.2 MW . Utilizing the
design . Accordingly, any or all of the basic components, i.e. , 50 design methodology of the present invention , a turbine
2

the rotor blades , the accelerator shroud , the annular diffus- having the same 16 m diameter rotor section will produce
ers , the hollow center hub , the tail rudder and /or the wildlife 3.88 MW , according to our “ theoretical calculations ” . This
and debris excluders can advantageously comprise, to at represents a 76 % increase in electrical output for the same
least some degree , asymmetrical hydrofoil shapes. The size turbine .
asymmetrical or unidirectional hydrofoil shapes are much 55 Below is a calculation used for output prediction for the
more efficient than symmetrical and bi- directional hydro- hydrokinetic turbine designs according to the invention :
foils.
The relationship and cooperation between those elements
that may include the asymmetric hydrofoil shapes , i.e. , the Theoretical Calculations of turbine output in relation to water flow speed
accelerator shroud , the rotor blades, the annular diffuser, the 60 Incoming Flow Velocity 3 Knots
hollow center hub and / or the wildlife and debris excluders Turbine Inside Diameter 16.000 Meters
produce a mutually beneficial and synergistic effect, which Predicted Turbine Power 3,882,476 W 3.88 MW
Nozzle diameter ratio 1.473 : 1
is enhanced as more of these elements are provided with the Nozzle influence , Velocity 2.948 : 1
asymmetric hydrofoil profiles . In the most preferred Flow tube available 23.573 M
embodiments, all five of these elements benefit from each 65 Flow Velocity in Nozzle 8.844 Knots 4.549746 M/ S
other's presence , and when combined together, their effect is Turbine Area 201.062 M2
amplified to create a much greater negative pressure field
 US 11,174,829 B2
21 22
-continued current or in a river current. The device can preferably be
mounted on any of these fixed structures by at least two
Theoretical Calculations of turbine output in relation to water flow speed different methods. Support structure to which the turbine is
Power Coefficient and Betz Law attached can be mounted either to one or two rails attached
5
to the fixed structure on which the unit is lowered into the
Density 1025.15 Kg/M ^ 3 water and raised up out of the water for maintenance or
Velocity 4.550 M/ S
Diameter = 16.000 M repair, or it can be mounted on a pivot which also allows the
Max Possible % (Betz ) 0.59 Cp device to be pivoted into the stream of water and back out
Betz Limit power P = 5,751,816 W of the water for maintenance or repair. Either way , the units
Predicted Turbine Cp 0.4 Cp 10
are held in place in the up position by a hitching mechanism ,
whereas in the down position it can rest on some end stops .
Installation Methods: The cable connection preferably goes to the base structure
The hydrokinetic turbines according to the invention can and from there to a transformer for conditioning.
be installed in practically any moving body of water or can 15 Buoyant installation ( FIG . 29 ) : The turbine unit or turbine
be moved through the water to create usable output. There units can be made naturally buoyant due to the composite
are five primary ways of installation and deployment meth- construction materials that can be employed for the con
ods for these hydrokinetic turbines: struction of any or all the parts. This allows the device to
Piling -mounted (FIGS . 21 , 22 ) : The turbine unit or units float at any given depth determined by the length of a tether
can be a piling mounted installation , which consists of a 20 ( 64 & 66 ) which is attached to a foundation / seabed mooring
piling (52 ) driven into the ocean floor or riverbed that has a (59 ) or screw - type anchor, or any other fixed device on the
set of rotational thrust bearings and a compression pivoting seabed or the riverbed . The two -part tether serves two
bearing on the top (53 ) . A larger pipe that that is attached to purposes: the fixed tether ( 64 ) and the rolling tether ( 66 ) is
the mounting structure (50 ) on which the turbine sits sleeves to hold the device submersed at the desired depth and to
over that fixed piling (52 ) and the bearings ( 53 ) . The 25 transmit electricity from the generator unit to the base and
mounting structure (50 ) can unbolt from the pipe ( 52 ) and then to shore. This tether ( 64 & 66 ) has 2 components ; a
has an electrical plug (53 ) inside the pipe that can be primary fixed tether ( 64 ) that is aa fixed length between the
unplugged for maintenance and turbine removal . This instal- turbine and the secondary rolling tether ( 66 ) which is a
lation allows the turbine unit to pivot and the turbine can rolling mechanism that is attached to the base and is the
freely rotate 360 ° to orient itself exactly into the direction of 30 equal in length to the distance between the water surface and
the water current. This type of installation also has a very the desired depth where the turbine is to be held . When the
small seafloor footprint and minimal impact on the environ- secondary tether is unrolled the turbine is allowed to float to
ment. In this installation the electrical power is transmitted the surface for maintenance or repair. The device may also
through a set of copper rings and charcoal brushes (53 ) be attached on aa submersible raft ( 58 ) or submerged flotation
inside the sleeve to avoid a cable being twisted and any 35 device (58 ) , to hold the turbine suspended in midstream . The
restraint on the pivoting action . same tether mechanism can be utilized in this case .
Floating structure -mounted ( FIGS . 23 , 24 , 25 , 26 , 27) : Towed installation (FIG . 30 ) : The turbine unit or turbine
The turbine unit or units can be attached to any kind of units can also be towed behind a vessel or be dragged
floating structure such as an ocean barge, a rail ( 54 ) , a ship through the water by other devices that propel the device
or a vessel floating on the surface of the water. These devices 40 through water that is not moving, to artificially create a
can either be anchored to the seabed or riverbed (59 ) or held water flow through the device . The towing cable is typically
in place by thrusters coupled to GPS location devices similar attached to the front of the wildlife and debris excluder, and
to oil rigs or tied to any structure in the ocean or in a river therefore would orient the turbine to optimally create the
or along shore. There are two types of raft mounted instal- flow from front to back through the unit . Instead of the single
lations , one is on a longitudinal pivot (FIG . 23 , 24 , 25 ) and 45 rudder that is usually located behind the exit of the turbine,
the other is on the transverse pivot (FIG . 26 , 27 ) . Preferably, there can alternatively be 2 or 4 winglets ( 62 ) attached to the
the raft mounted device either employs a hoisting system or outside of the annular diffuser; with one winglet on each side
a crane that is installed on deck or a helical gear driven and one winglet on top and bottom . These winglets ( 62 )
device to pivot the turbine onto the deck . One type of prevent the turbine unit itself from rotating as it is towed
installation utilizes only one raft or barge, whereas the 50 through the water, thereby ensuring that only the rotor
transversely mounted system employs two rafts or barges, section is rotating.
with the turbine unit mounted in between them . Depending Maintenance Procedures:
on the size of the turbine, the location or the operator's The hydrokinetic turbines of the invention require only
preference, one type of installation can be better than the minimal maintenance, due to the design of the components
other. For larger systems it is usually advantageous to use 55 and because the preferred composite construction materials
two rafts or platforms and mount the turbine between the are virtually corrosion free. However just like everything
two on the central transverse axis ( FIG . 26 , 27) , on which the that is submersed in the ocean over a certain length of time
turbine can be pivoted 180 ° to be above the water for fouling and marine growth will occur. These hydrokinetic
maintenance or repair. For smaller units the turbine or turbines are coated with non- toxic antifouling paints, but
turbines can be mounted over the side of the floating 60 still need periodic cleaning of the surfaces to ensure optimal
structure and be pivoted on the longitudinal axis (FIG . 23 , functionality and output. These units can be pressure washed
24 , 25 ) , to be placed on the deck of the structure for by a diver while they are submerged which allows them to
maintenance or repair. remain underwater or they can be brought to the surface and
Land- based structure -mounted ( FIG . 28 ) : The turbine unit be pressure washed by ground personnel. Other than peri
or turbine units can also be mounted to a land -based struc- 65 odic cleaning, these units require very little maintenance .
ture such as a seawall , a shoreline or be attached to a bridge Depending on the type of installation , the preferred main
pillar or other structures installed in the stream of an ocean tenance procedures may vary , as discussed below .
 US 11,174,829 B2
23 24
In the case of a piling -mounted installation (FIG . 21 , FIG . 30 years of experience as a designer working in the field of
22 ) , it is preferred to utilize a special maintenance vessel fluid dynamics, and after having created and built many
( also designed by the Applicant) that is a catamaran vessel different types of hydrofoils in his professional life, the
having a removable deck between the two hulls, and a gantry Applicant came to the basic concepts underlying the design
with aa hoist installed over that removable deck . The vessel 5 of the turbines according to the invention . With these basic
can be positioned above the turbine that needs maintenance, design concepts , he believes that his turbine designs accord
and the turbine unit can be lifted by reaching through the ing to this invention provide hydrokinetic turbines that will
opening in the deck between the two hulls and hoisting the surpass and outperform any other design that is currently in
turbine onto the boat . The electrical wire connecting the
turbine to shore leads to copper rings and brushes (53 ) that 10 existence .
Today there are many environments in which hydroki
are located inside support piling for pivoting ( 52 ) has a netic turbines are used that are characterized by a reversing
waterproof plug (53 ) that can be unplugged when the turbine current flow , and as a result much of the modern design work
is lifted up by the maintenance vessel located above . On the has focused on providing bi - directional turbines that can
vessel , the turbine that was just removed from the piling can effectively be employed in such environments, mainly tidal
be put off to one side , onto one of the hulls, and a spare 15 currents . Consequently, many of these bi - directional tur
turbine sitting ready on the other hull can be lowered
through the opening and plugged and bolted back onto the bines either embody little or no hydrofoil- embodying com
piling , from which the first unit was removed . ponents, or if they do , the hydrofoil designs are necessarily
In the case of a raft-mounted installation , it is preferred to symmetric . However, the cross - section lift coefficient of an
attach the support structure (50 ) of the turbine either longi- 20 asymmetric or cambered hydrofoil is greater than that of a
tudinally alongside the raft or transversely between two rafts symmetric hydrofoil, this design of the unidirectional hydro
( FIG . 23 , 24 , 25 , 26 , 27 ) In each case , a support structure
9 kinetic turbines according to the present invention takes
( 55 ) is used that is mounted on pivot points with bearings advantage of that phenomenon .
( 55 ) , which allow the unit to pivot around a central axis It was determined that it made the moat sense to primarily
either 270 ° in the case of longitudinally mounted units ( FIG . 25 optimize hydrokinetic turbines according to the invention
23 , 24 , 25 ) , or 180 ° in the case of transversely mounted units for a 3 kn current ( e.g. , see the embodiment depicted in
( FIG . 26 , 27 ) . A locking mechanism is used to hold the units FIGS . 34 and 35 ) because currents around 3 knots are the
in place when submerged for power generating, as well as most commonly occurring currents in ocean currents , as
when surfaced for maintenance or repair. To surface the unit, well as in tidal currents and also in many river currents.
a crane or hoist ( 56 ) installed on the raft is employed that can 30 There are also examples of locations and / or circumstances in
attach to the support structure of the turbine . Once unlatched which higher current speeds between about 5 kn and 7 kn are
in the submerged position , the crane can pull the unit out of commonly found , e.g. , in areas where special geographic
the water by pivoting the unit into the maintenance position features are present such as , for example, rapid flowing tidal
where it can be secured by latching into position . currents or river currents , or even ocean currents in rare
In the case of a fixed structure mounted installation ( FIG . 35 instances , and then also in the case of towing one of the
28 ) , the turbine units can be maintained or repaired by at hydroturbines behind a watercraft, typically a sailboat . In
least two methods. One method is to have a floating platform order take into account these higher current speed situations ,
or raft that is put in place after the turbine is hoisted out of the application also describes design modifications intended
the water, either by sliding the turbine mounted to the for embodiments designed for a 6 kn current, as being
support structure upwardly on the rails of the fixed structure , 40 representative of and also exemplifying turbines intended
or to make the units mounted on the support structure for use in environments exhibiting these higher current flow
upwardly out of the water. The other procedure is to have a velocities . Therefore , the application describes embodi
platform that is attached to the fixed structure that can swing ments that are representative of designs for use at these two
out of the way for raising the turbine units out of the water most ( i.e. , nearly all ) commonly encountered flow speeds .
and then be repositioned for servicing . 45 Of course , following the teachings of this application, the
In the case of buoyant installation , there are also at least turbines according to the invention can be optimized for any
two ways of servicing the turbine units. In the case of a flow speed , which from a practical standpoint includes
buoyant turbine that is tethered to the seabed or the riverbed currents ranging from about 1/2 kn to up to about 12 kn of
by a fixed tether ( 64 ) that is attached to the rolling tether ( 66 ) flow speed .
is lengthened by unrolling the pulling mechanism ( described 50 There are many standard algorithms used in fluid dynam
in the installation description above) and bringing the tur- ics to calculate the shape of hydrofoils, and the standard
bine to the surface . Once at the surface , the turbine unit can textbooks and databases contain complete information and
be hoisted onto the deck of a vessel for maintenance or tables pertaining to such calculations and known designs.
repair. In the case where the turbine units are attached to a These need not be discussed in the present context , since
submerged raft ( 58 ) or flotation device, the rolling tether 55 they are well known to those skilled in the art. However, as
( 66 ) pulling mechanism unrolled in the same manner as with is discussed below, in some embodiments, the present inven
a buoyant turbine, and once at the surface the turbine units tion utilizes these algorithms/databases in a novel design
can be pivoted up onto the platform for servicing. regimen, as a starting point to design novel hydrofoil shapes
In the case of a towed installation , the towing line that serve as the so - called “ initial ” designs in the first stages
attached to the turbine unit is hauled in to bring the turbine 60 of the hydroturbine design process .
unit alongside or behind the vessel , where it is typically According to one mode , the design process typically starts
picked up by a hoist or a crane mounted on the vessel . The out with hand - drawn sketches (usually hut not necessarily
turbine is then preferably placed on the deck of the vessel for novel ) based upon conventional fluid dynamic consider
maintenance or repair. ations , which sketches are selected based upon the novel
Methodology of Design 65 principles according to this invention . The selected sketches
The way in which the turbine units of this invention have are subsequently entered into a computer program of the
been designed is believed to be novel and unique. After over type called a 3 - D modeling program , one example of which
 US 11,174,829 B2
25 26
is called “ Rhino 3 - D ” or “ SolidWorks " . This results in a first the length of cord , the thickness of the cord / profile and the
version of the " initial ” designs. incidence of the cross - section each preferably changes, more
Alternatively, the first version of the “ initial” design can preferably changes continuously, from the root of the blade
be produced by selecting various different hydrofoil shapes out to the tip of the blade . During the first stage of the design
from one of the databases, such as the archives of the 5 process, as many modifications as possible are made by
National Advisory Committee for Aeronautics (NACA ), intuitively applying fluid dynamic considerations, to arrive
again based upon the same conventional fluid dynamic at a modified “ initial” design. As is understood by persons
considerations that are employed in fashioning the hand- skilled in the art, this is typically done with the aid of
drawn sketches, but again the shapes are selected ( from software products designed to assist such design activities ,
among a huge number) based upon novel design consider- 10 such as , for example, programs called “ JavaProp,”
ations taught in this application . The shapes of these first " QBlade ,” and the like . ( The variations described here can
version , “ initial” intuitive hydrofoil shapes ( irrespective of generally be visualized by looking at the preferred final or
how arrived at) are modified with the 3 - D modeling soft- " optimized” embodiment illustrated in FIG . 34 , which
ware, such as Rhino 3D or SolidWorks and analyzed in a depicts a rotor blade profile that, is “ optimized ” (in the
2 - D flow analysis program , such as “ Java Foil ” or the like , 15 second stage ) for a 1.5 m diameter of the rotor blade section ,
and other similarly commercially available software prod- for use in a 3 kn current. It is clearly visible how all the
ucts for this purpose . This modification proceeds by viewing parameters defining the hydrofoil shape of the blade and its
the selected “ initial ” profiles in 3 - D and making modifica- incidents change between the root and tip of the blade . )
tions thought to be favorable based upon fluid dynamic With reference to FIGS . 37A and 37B of the drawings, the
considerations, so as to maintain laminar flow anda avoid 20 former shows the flow acceleration in 2 - D velocity resulting
turbulence , while maintain maximum flow speed . As a result from software analysis, whereas the latter is a related
of this first stage , modified “ initial” designs are created that presentation showing flow acceleration in 2 - D pressure .
represent new (novel ) and unique shapes of hydrofoils Both figures clearly show areas of enhanced acceleration
according to the principles of the invention, which are then resulting from the design characteristics according to the
made into an annular or a nozzle shape, for the purpose of 25 invention .
employing them in the context of a hydroturbine. Turning now to the second stage of the development
Generally, when considering design for a single selected process , those modified “ initial” shapes created in the first
current speed , such as , for example, 3 knots, the size of stage of design are then analyzed for their efficiency working
hydroturbines according to the invention can be scaled up or together in a turbine environment in creating the greatest
down with typically only minor changes in the overall 30 pressure differentials and with the least turbulence to
configuration. The main influencing factor of the choice of achieve maximum water flow acceleration through a nozzle .
an " initial” hydrofoil shape, and then the further modifica- This is the " optimization ” step , in which final, optimized
tion of that profile, is the flow speed of the water current in shapes are determined for each of the hydrofoil components .
which the turbine is to be placed . In higher flow speeds such For this analysis there is utilized what , is willed Computa
as 6 kn , for example, the cross - section of the hydrofoil 35 tional Fluid Dynamics (CFD ) . As is well known, this testing
shapes are generally more slender and flatter ( less camber on is always done in aa 3 - Dimensional framework . These simu
both sides of the hydrofoil) then they are in a profile design lations can be done in any known CFD computer program ,
for aa 3 kn current, where the cross - section of the hydrofoil such as one called “ STAR CCM + " which is one of the most
would be more curved and thicker (more camber on both advanced softwares in this field . This software enables the
sides of the hydrofoil). This is generally illustrated in FIG . 40 designer of an intuitively created hydrofoil shape to analyze
33 , where the differences in the respective cross - sections or and optimize flow characteristics in a virtual environment
profiles are clearly visible . In higher flow speeds , the cord of prior to building prototypes for real life testing.
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 45 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 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 ) . 50 in the water flow that could reduce the efficiency. With
These modifications ( carried out in the 3 - D modeling soft- reference to FIG . 38B , there are shown the pressure fields
ware) are always done to create optimal lift and maximum that result from the 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 55 the annular diffuser added on, demonstrate a synergistic
to move to the second stage of the design process ( discussed effect of the elements together creating a much greater
below ) in which the modified “ initial” design is subjected to pressure differential.
the more quantitative optimization using CFD analysis . In CFD , the program creates an elaborate mesh of poly
The rotor blade shape is designed in the same fashion as hedral shapes to simulate the fluid volume and a very precise
the center hub and accelerator shroud . Thus, a suitable 60 shape of the turbine in the form of a mesh composed of
" initial ” hydrofoil shape is sketched or chosen from the millions of triangles. Afterwards, this newly created model
library, for the cross - section of the rotor blade , in accordance is run through the solver of the program , which analyzes the
with the principles of the invention, and then modified fluid /water flow (polyhedral bodies ) over the turbine shape
( utilizing fluid dynamics principles ) based upon the speed ( triangle mesh) and shows the flow paths created by it . In
with which it travels through the water, which speed is 65 this way, the final optimized shapes and configuration of the
greater at the tip of the blade than at the root of the blade. components are arrived at by making changes and assessing
Accordingly, the hydrofoil cross - section of the rotor blade, the consequences of those changes based on the testing
 US 11,174,829 B2
27 28
feedback provided by CFD analysis, until a final optimum a -continued
combination of shapes is achieved .
Once all the hydrofoil shapes are optimized and shown to 78 Twist of blade measured in degrees 23 °
95 Flow direction
work in harmony with one another, the potential energy 5
extraction or electrical output is calculated . Here is an
exemplary result of the analysis of aa particular blade shape Legend for FIG. 35
developed during the early phase of the design , using CFD
to analyze pressure differential between both sides of the 83 Diameter of diffuser entrance 2.430 m
rotor blades ( intrados and extrados) as they rotate through 10
84 Diameter of accelerator shroud 2.217 m
the water (to determine optimum shape and number of 85
entrance
Overall diameter of center hub 0.665 m
blades ) . Reference here is to FIGS . 39 and 40 , which 86 Profile / cord thickness of center hub 0.084 m
illustrate the respective high and low pressure zones on the 87 Length of accelerator shroud 1.651 m
two sides of the rotor blades . 88 Length of diffuser 1.188 m
It will be appreciated that there are elements of trial and 15 89 Length of center hub 1.131 m
90 Profile /cord thickness of accelerator 0.260 m
error involved not only in the first stage but also to some shroud
degree in the second stage of the process . In the first stage , 91 Profile / cord thickness of diffuser
Diameter of center hub exit
0.158 m
the trial and error is informed not only by the skill of the 92
93 Diameter of accelerator shroud exit
0.500 m
1.917 m
artisan applying the principles taught in this application , but 94 Diameter of diffuser exit 2.694 m
also by an intuitive application of the general principles of 20
fluid dynamics, and more importantly by the quantitative
test results provided by the various types of software that are areSubsequently analyzed in
, the structural aspects of the design shape
a Finite Element Analysis program , such as
a
applied to verify the effects of each modification made to the that called CD -Adapco
individual component designs. In the second stage , where structural engineering isFBA , Scan and Solve or similar. This
to confirm that the shapes of the
testing is done in 3 - Dimensions and for combinations of 25 profiles that have been determined can actually be built with
components , there are obviously many opportunities for the requisite strength, e.g. , with composite materials. There
changes that can be made ; however, optimization is rela- are also several other software programs that can also be
tively straightforward at this point. From the CFD analysis , utilized along the way , such as SolidWorks, AutoCAD , with
areas evidencing lack of laminar flow and / or turbulence can mechanical event simulation, but they are minor contribu
be detected and then modified to remove these unwanted 30 tors to the design.
flow effects. Typically, the target is considered to be what is Once the shapes of the turbine are determined by intuitive
theoretically believed to be the maximum possible improve design CFD
/ sketching, optimizing of shapes in 3 - D modeling and
analysis , stage III of the development begins . This
ment in results, for example, an increase in flow speed Stage is the physical building of a fully functional prototype
through current
ambient the turbine of. about
velocity three ,times
Alternatively a targettheofincoming
a certain, 35 documenting
and testing inallrealparameters
-life conditions
improvement in turbine power output, compared to known, recording of rpm of the rotor section of the while
design monitoring and
. This involves
comparably sized turbine, can be chosen . When either or , electrical output of the
both of these targets is / are approached or reached, optimi turbine unit, video recording of the flow characteristics
zation is considered to be achieved . For example, in FIGS . 40 through a wind
tufting of all surfaces ( similar to an airplane wing in
tunnel ). These tests are conducted at various different
34 and 35 the essential dimensions are shown for one
preferred embodiment of a turbine according to the inven flow speeds from 1 kn up to 6 kn utilizing various configu
tion, namely, a 1.5 meter diameter turbine that has been rations of accelerator shroud shapes annular diffuser shapes
and rotor section shapes . Ultimately this test results , in final
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 . 45 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
72 Angle of incidence measured in Angle between axis of flow utilized to improve the extraction the maximum power out
degrees direction and axis of of any given naturally occurring water current by site
74 Profile / cord length measured in
profile /cord length
Distance between leading
50 specific design. The first step of site -specific design consists
meters edge and trailing edge of flow data collection of the characteristics at a specific
75 Length of rotor blade Distance between root and tip location or site . The flow speeds , the flow direction , the flow
76 Profile /cord thickness measured in
of blade
Maximum distance between
mass characteristics ( volume of water flowing at any specific
meters intrados and extrados time) and the fluctuations in flow over a given period of time
78 Twist of blade measured in degrees Difference between incidence 55 will be precisely measured and recorded with the aid of
at root of the blade and acoustic Doppler equipment. The second step is to assess ,
incidence at tip of blade log and record the types and quantities of sea life and
wildlife in the area chosen for the installation site by
prolonged video recording, diving and logging of all the
60 species and size of sea life. It is also necessary to log the type
72 Angle of incidence at root of blade 35 ° and quantity of debris floating in the water. There after the
72 Angle of incidence at tip of blade 58 ° above stated design methodology can begin and then an
74 Profile cord length at root of blade 0.181 m optimized turbine for a specific site can be developed by first
74 Profile /cord length at tip of blade 0.588 m
slightly adjusting the hydrofoil shape of the accelerator
75 Length of rotor blade 0.498 m
76 Profile / cord thickness at tip of blade 0.035 m 65 shroud, the diffuser, the center hub and the rotor blades , and
76 Profile / cord thickness at root of blade 0.107 m then adjusting the spacing of the bars on the wild life and
debris excluder to the local needs . This will assure that no
 US 11,174,829 B2
29 30
wildlife is harmed by the turbine, that the turbine does not blades, each blade having two edges and extending
get harmed by floating debris, and that the maximum amount radially outwardly from a radially inner base end
of energy /electricity can be extracted at the precise location . thereof, at which base end each blade is mounted on
All of the computer programs that have been mentioned said center hub member for rotation therewith , said
in the foregoing description of the methodology of the 5 blades having an asymmetrical hydrofoil - shaped cross
present invention are commercially available, and their sectional configuration and terminating at radially outer
modes of use are likewise well known to persons skilled in blade tips , wherein said force - generating member is
this art. mounted at said outer blade tips for its support and for
Thus, the Applicant has conceived of certain novel rotation , within the wall cross - section of said accelera
designs for hydrokinetic turbines, has furthermore taken 10 tor shroud; and a rotor outer ring , to which the blade
concepts, tools and information from a number of different tips are attached and which has an outer circumference
fields, and has employed and / or combined them in aa novel that is configured for rotation within said open space of
manner to design unidirectional hydrokinetic turbines that
exhibit a significantly higher efficiency. This is due largely the accelerator shroud wall cross - section , wherein the
to the synergistic interaction of multiple, novel turbine 15 hydrokinetic force -generating member comprises a
components that embody novel asymmetric hydrofoil char unitary, rotating rotor assembly ; and
acteristics, which have been fine - tuned in a new way for the an annular diffuser comprising, a cylindrical ring member
specific environment in which they are to be employed. The that has aa wall cross -section comprising an asymmetri
“ Novelty of Design Process ” is evident because never before cal hydrofoil shape, said annular diffuser having a
have engineers and designers been able to achieve the highly 20 diameter greater than the diameter of said accelerator
efficient results as demonstrated in connection with the shroud and being spaced apart radially from the accel
hydrokinetic turbines according to the present invention . erator shroud and being positioned so as to extend
These efficiencies permit the turbines of the invention to be behind the main accelerator shroud , in the sole direc
usefully employed in many contexts in which the current tion of water flow through the turbine, in an axially
speed is too low to permit use of prior an turbines. 25 overlapping relationship with the accelerator shroud .
The design of these hydrokinetic turbines and /or compo- 2. A unidirectional hydrokinetic turbine as claimed in
nents is unique because of the fact that no other design up claim 1 , wherein said center hub has a length that extends
until the present has combined every possible hydrodynamic both forwardly and rearwardly past the edges of said blades .
advantage, let along in novel combinations (in component 3. A unidirectional hydrokinetic turbine as claimed in
selection , component design and interaction of these com- 30 claim 2 , wherein said center hub extends from the blades
2

ponents together) to optimize the output of the turbine and forwardly to a first point that is rearward of the water
accelerate the flow of the water to extract more energy as is entrance end of said accelerator shroud, and extends rear
possible with the turbines of the present invention . Although wardly to a point at least as far as the water exit end of said
hydrodynamic principles are well known , the use of these accelerator shroud .
principles and the combination of novel designs and the 35 4. A unidirectional hydrokinetic turbine as claimed in
effects of all the different elements used in this design , claim 3 , wherein said center hub extends a total distance of
a

especially the mutually beneficial and synergistic effects of approximately 2/3 of the length of said accelerator shroud.
these elements combined together, are new and inventive . As 5. A unidirectional hydrokinetic turbine as claimed in
demonstrated in this design , each and every element is claim 1 , wherein said hydrokinetic force - generating member
initially designed and then optimized for the flow speed and 40 further consists essentially of at least one magnet mounted
size of turbine, and therefore the end result is a hydrokinetic on the rotor outer ring for rotation with the rotor assembly.
turbine with much greater output and efficiency than other 6. A unidirectional hydrokinetic turbine as claimed in
designs proven up to present. claim 1 , wherein the profile of the open space formed
What is claimed is : between the radially inner wall and the radially outer wall
1. A unidirectional hydrokinetic turbine having a water 45 spaced apart from the radially inner wall of the accelerator
entrance end and a water exit end defining a sole direction shroud comprises an asymmetric hydrofoil cross - section in
of water flow through the turbine, comprising : the axial direction of water flow .
a cylindrical accelerator shroud that comprises a radially 7. A unidirectional hydrokinetic turbine as claimed in
inner wall and a radially outer wall spaced apart from claim 6 , wherein the accelerator shroud has a forward
the radially inner wall , to form a radial wall cross- 50 portion upstream of the blades and a rearward portion
section that defines an open space extending axially in downstream of the blades , and wherein the asymmetric
the sole direction of water flow , and that defines within hydrofoil profile comprises an S - shaped profile in which the
its cylindrical cross - section a water flow area for water radially outer wall surface comprises a forward convex
flowing in the sole direction, the water flow area portion and a rearward concave portion , and the radially
containing therein structure that consists essentially of 55 inner wall surface comprises a rearward convex portion and
an integral hydrokinetic force -generating member that a forward portion, measured from the blades to the water
rotates during force generation within the accelerator entrance end that has a shape that is either straight or
shroud, the integral force generating member consist concave .
ing essentially of: a rotating center hub member having 8. A unidirectional hydrokinetic turbine as claimed in
an open center surrounded by an inner wall , wherein 60 claim 7 , wherein the radially inner surface of the forward
2

the rotating hub member has aa round profile transverse portion of the S - shaped profile is concave .
to the sole direction of water flow , having an outer wall , 9. A unidirectional hydrokinetic turbine as claimed in
and wherein the inner well surrounding the open center claim 1 , wherein the accelerator shroud has aa diameter at its
and the outer wall together form in the axial direction water exit end that is greater than the diameter at its water
an asymmetric hydrofoil profile, having an extrados 65 inlet end, and wherein the annular diffuser has aa diameter at
facing toward the outside of the turbine and an intrados its upstream end that is less than its diameter at its down
facing toward the center of the hub; a plurality of stream end.
 US 11,174,829 B2
31 32
10. A unidirectional hydrokinetic turbine as claimed in
claim 1 , wherein at least some of said blades have aa chord
length at their radially outer ends that is greater than the
chord length at their radially inner ends .
11. A unidirectional hydrokinetic turbine as claimed in 5
claim 10 , wherein said blades have a profile thickness at
their radially outer ends that is greater than the profile
thickness at their radially inner ends .