US008307945B2

(12) United States Patent (10) Patent No.: US 8,307.945 B2

Todorovic (45) Date of Patent: Nov. 13, 2012
(54) GAS-TURBINE EXHAUST CONE (56) References Cited
(75) Inventor: Predrag Todorovic, Berlin (DE) U.S. PATENT DOCUMENTS
938,101 A * 10/1909 Winters ........................ 181,264
(73) Assignee: Rolls-Royce Deutschland Ltd & Co 2,853,148 A * 9/1958 Billey ... ... 181,265
KG (DE) 2.934,891. A * 5/1960 Brown ............................ 60,761
3.286,786 A * 1 1/1966 Wirt .............................. 181,213
(*) Notice: Subject to any disclaimer, the term of this 3.286,787 A 11, 1966 Wirt
patent is extended or adjusted under 35 4,004,416 A * 1/1977 Amelio et al. .................. 60,264
U.S.C. 154(b) by 0 days. (Continued)
(21) Appl. No.: 13/180,073 FOREIGN PATENT DOCUMENTS
EP 1391597 2, 2004
(22) Filed: Jul. 11, 2011 OTHER PUBLICATIONS
(65) Prior Publication Data German Search Report dated Apr. 8, 2011 from related foreign appli
US 2012/0006614 A1 Jan. 12, 2012 cation.

(30) Foreign Application Priority Data Primary Examiner — Edgardo San Martin
(74) Attorney, Agent, or Firm — Timothy J. Klima;
Jul. 12, 2010 (DE) ......................... 10 2010 O26 834 Shuttleworth & Ingersoll, PLC
(51) Int. Cl. (57) ABSTRACT
FO2K L/04 (2006.01)
FOIN I/02 (2006.01) A gas-turbine exhaust cone includes a cone shaped outside
FOIN I/08 (2006.01) cone 1 closed in a flow direction, an inside cone 2 arranged in
FOIN I/2 (2006.01) the outside cone 1 over at least part of the length of the exhaust
FO2K I/OO (2006.01) cone, with the inside cone 2 being connected to the outside
FOIN 1/00 (2006.01) cone1 via at least one helical partition wall3, thereby forming
(52) U.S. Cl. ........ 181/213; 181/250; 181/273; 181/274; an interspace 4 between the outside cone1 and the inside cone
181/276; 181/279; 415/119:60/770 2. The interspace 4 is connected to inlet openings 5 at its
(58) Field of Classification Search .................. 181/213, inflow side and opens at an exit side 6 towards an interior 7 of
181/215, 216, 217, 219, 222, 250, 270,273, the outside cone 1. A dampening element 8 is arranged in the
181/274,276, 279, 280, 295, 225; 24.4/1 N: outside cone 1 adjacent to the exit side 6 of the interspace 4.
415/119; 60/770, 771
See application file for complete search history. 20 Claims, 3 Drawing Sheets
 US 8,307.945 B2
Page 2

U.S. PATENT DOCUMENTS 5,912,442 A *ck 6/1999 Nye et al. ...................... 181,292
4,044,555 A * 8/1977 McLoughlin et al. .......... 60,264 SEA 358 SA. A ''.
4,050,539 A * 9/1977 Kashiwara et al. ........... 181/280 6547,032 B2 * 4/2003 Yoonetail. 181/239
4,064.961. A 12, 1977 Tseo................. 181,213 6,615,576 B2 * 9/2003 Sheoran et al. ................ 60,395
4,105,090 A * 8/1978 Tachibana et al. ............ 181,265 6.799,657 B2 * 10, 2004 Daniels ........ 181,252
4,137,992 A ck 2f1979 Herman 6,845,607 B2* 1/2005 Lair ......... ... 60,263
4,199.936 A 4, 1980 Cowan et al. ................ 60,226.1 6,935,834 B2 * 8, 2005 Lata Perez 415,115
4,226,297 A * 10/1980 Cicon ........................... 181,213 7451855 B2 : 1/2008 Wang 181,286
35E A ck 18 Yy 181,213 7,784,283 B2 * 8/2010 Yu et al. ... 60,770
4947,958. A * 8/1990 s . . . . . . . . . . . . . . . . . . . . . . . . . 181,296 7,891,195 B2 * 2/2011 Bouty et al. ... 60,770
6. A 36 S. 181290 8,025,122 B2 * 9/2011 Gilcreest et al. 181,213
5.49.30 A 2/1996 on si/286 8,037,967 B2 * 10/2011 Mercat .......................... 181,292
5670,758. A * 9/1997 Borcherset al. 181,286 2010/025 1718 A1* 10/2010 Ito et al. .......................... 6Of 725
5,760,349 A * 6/1998 Borchers et al. .............. 181,286 * cited by examiner
U.S. Patent Nov. 13, 2012 Sheet 2 of 3 US 8,307.945 B2
U.S. Patent Nov. 13, 2012 Sheet 3 of 3 US 8,307.945 B2
 US 8,307,945 B2
1. 2
GAS-TURBINE EXHAUST CONE The helical or spirally shaped partition walls are arranged
at an angle relative to the local radial direction of the outside
This application claims priority to German Patent Appli cone. The partition walls are preferably welded to the outside
cation 102010026834.8 filed Jul. 12, 2010, the entirety of cone, while they may be joined to the inside cone with blind
which is incorporated by reference herein. 5 rivets.
This invention relates to a gas-turbine exhaust cone The helical partition wall is highly suitable for compensat
arranged at the outflow area of a gas turbine. ing thermal expansion since the latter results in displacement
Gas turbines for aircraft engines require noise abatement. mainly in the axial direction, but not in the radial direction.
For this, various measures are known to minimize the noise of This enables the loads on the outside cone to be substantially
the gas stream exiting from an exhaust nozzle downstream of 10 reduced. The helical partition walls accordingly twist
the turbine. together with the inside cone relative to the outside cone.
From the state of the art it is known to dampen the low According to the present invention, a Solid and stable
frequencies occurring in particular on engines with lean com design with low Susceptibility to thermal loading is provided.
bustion. Noise dampening is here accomplished by means of This enables a thinner and therefore lighter outside cone to be
a Helmholtz resonator. It is known to provide such a Helm 15 conceived.
holtz resonator in the inflow area of the exhaust cone, while The dampening element according to the present inven
the downstream end area of the exhaust cone is merely con tion, which is provided preferably in plate form, preferably in
ceived as geometric body. Known Helmholtz resonators are a honeycomb structure, is connected to the outside cone pref
here provided as a system of radial walls and inner cylindrical erably via bellows, so that thermal loading is avoided also in
ducts and dimensioned in dependence of the frequencies. this case.
The known designs disadvantageously require reinforcing Thus, a Substantial increase in mechanical strength,
elements as they are heavily mechanically loaded in terms of together with a reduction in size and an improvement of the
the gas temperatures occurring. Also attributable to different dampening effect, are obtained
walls and stiffening elements, the resultant design features a In a favourable embodiment of the present invention, it is
relatively high weight. Additionally, manufacture thereof 25 provided that a second dampening element is arranged in the
requires high effort and investment. Manufacturing costs are interior of the inside cone in the inflow area of the exhaust
still further increased by internal acoustic measures (perfora cone. This is again preferably located via bellows to compen
tions or similar). Further, the axial length of such a resonator sate for thermal expansion or contraction.
requires considerable installation space, adding to the weight The present invention is more fully described in light of the
of the arrangement. 30 accompanying drawings showing preferred embodiments. In
In a broad aspect, the present invention provides a gas the drawings,
turbine exhaust cone of the type specified at the beginning FIG. 1 shows a perspective partial sectional view of an
which, while being simply designed and having a high damp exhaust cone in accordance with the present invention,
ening effect, can be manufactured cost-effectively and is FIG. 2 shows an axial sectional view of the exemplary
characterized by low weight. 35 embodiment as per FIG. 1, and
The exhaust cone according to the present invention first FIG.3 shows a sectional view as per A-A of FIG. 1.
has an outside cone which is essentially closed in a flow The exhaust cone according to the present invention
direction. According to the present invention, an inside cone includes an outside cone 1 tapering in flow direction, as
extends within the outside cone over at least part of the length known from the state of the art. As per FIG. 2, inflow is
of the exhaust cone and is connected to the outside cone via at 40 accordingly from the left, with the exhaust stream exiting
least one helical partition wall. The resultant design is a from the turbine of an aircraft engine not being shown.
double cone with an interspace formed between the outside At its inflow area, the outside cone 1 is provided with inlet
cone and the inside cone. Extending in this interspace is the at openings 5 (perforation) through which the sound waves 12
least one helical partition wall. The interior is connected at an produced by the exhaust stream can enter the outside cone 1.
inflow side to inlet openings allowing Sound waves to enter. 45 In parallel with the outside cone 1, an inside cone 2 is pro
These propagate in the interspace. The helical partition wall vided which extends over a part of the axial length of the
provides for a considerable running length. Thus, with the outside cone 1. The inside cone 2 is connected to the outside
Sound wave running length required for the Helmholtz reso cone 1 by helical or spirally shaped partition walls 3. Here, it
nator principle being provided by the helical partition wall, is preferably provided that the connection between the parti
the axial length of the exhaust cone according to the present 50 tion walls 3 and the outside cone 1 is made by welding, while
invention can be very short. a connection of the partition walls to the inside cone 2 can be
On the exit side, the interspace opens to an interior of the made by riveting or similar. Other fastening methods can also
outside cone, with a dampening element being disposed in the be used.
outside cone adjacent to the exit side through which the Sound FIG. 2 shows an interspace 4 formed between the outside
waves enter the interior of the outside cone. 55 cone 1 and the inside cone 2. As a result of the helical design
In a particularly advantageous embodiment the present of the partition walls, an effective length 15 of the spiral
invention provides for several spirally shaped partition walls. chamber formed between the partition walls 3 in the inter
The arrangement of the exhaust cone according to the space 4 is obtained. This effective length 15 enables an effi
present invention enables a Helmholtz resonator to be pro ciently operating Helmholtz resonator to be provided, in par
vided which is suitable for reducing in particular the low 60 ticular in connection with the W4 effect of the dampening
noise frequencies resulting from lean combustion. element 8 described hereafter.
The Sound waves accordingly reach the spirally shaped The sound waves represented in helical form in FIG. 2
Helmholtz resonator via the inlet openings. The spirally issue on the exit side 6 of the interspace 4 and reach an interior
shaped, helical partition walls (preferably provision is made 7 of the outside cone 1. Here, the sound waves impinge on a
for several such partition walls) provide the required length of 65 flat dampening element 8 which can be provided with a hon
the Helmholtz resonator without the need to increase the eycomb structure and conceived in the form of a W/4 resona
installation length of the exhaust cone. tOr.
 US 8,307,945 B2
3 4
FIG. 2 shows reflected sound waves 16 which may still be 4. The gas-turbine exhaust cone of claim 3, and further
issued from the dampening element 8. These reflected sound comprising a second dampening element positioned in an
waves 16 enter an interior 9 of the inside cone 2 and impinge interior of the inside cone at the inflow side.
on a plate-type dampening element 10 which is also provided 5. The gas-turbine exhaust cone of claim 4, wherein at least
as a W4 resonator. one of the dampening elements has a plate form, with a
The dampening element 10 is connected to, and located on, honeycomb structure and acts as a W/4 resonator.
the inside cone 2 via bellows 14. Analogically, the dampening 6. The gas-turbine exhaust cone of claim 5, wherein the
element 8 is located on the outside cone 1 by bellows 13. spirally arranged partition walls are positioned at an angle of
Location and attachment of the entire exhaust cone is 5° to 15° to a perpendicular on a surface of one of the outside
accomplished by an annular mounting flange 11. This mount 10
and inside cones.
ing flange 11 is preferably firmly connected to the outside 7. The gas-turbine exhaust cone of claim 6, wherein at least
cone 1, while an expansion gap can be provided at the tran one of the dampening elements is a high-frequency damp
sition to the inside cone 2 to compensate for thermal loading C.
by contraction or expansion. 8. The gas-turbine exhaust cone of claim 7, and further
With reference numeral 17, FIG. 2 shows an angular ref 15
comprising an annular mounting flange connected to the out
erence line illustrating that the partition wall is arranged at an side cone at an end area on the inflow-side end area.
angle of 5° to 15°, preferably 10°, to the reference line verti 9. The gas-turbine exhaust cone of claim 8, wherein an
cally aligned to the envelope Surface of the outside cone 1 and interior of the exhaust cone opens to an exterior only via the
the inside cone 2 arranged parallel thereto. plurality of inlet openings.
The two dampening elements 8, 10 are each provided as flat 10. The gas-turbine exhaust cone of claim 1, wherein the at
high-frequency dampeners. least one inlet opening includes a plurality of inlet openings in
FIG. 3 is a sectional view showing the inclination of the perforation form.
partition wall at an angle C. to the radial direction 17. 11. The gas-turbine exhaust cone of claim 1, and further
comprising a second dampening element positioned in an
LIST OF REFERENCE NUMERALS interior of the inside cone at the inflow side.
25 12. The gas-turbine exhaust cone of claim 11, wherein at
1 Outside cone least one of the dampening elements has a plate form, with a
2 Inside cone honeycomb structure and acts as a W/4 resonator.
3 Partition wall 13. The gas-turbine exhaust cone of claim 2, wherein the
4 Interspace spirally arranged partition walls are positioned at an angle of
5 Inlet opening 30 5° to 15° to a perpendicular on a surface of one of the outside
6 Exit side and inside cones.
7 Interior of outside cone 1 14. The gas-turbine exhaust cone of claim 1, wherein the
8 Dampening element first dampening element is a high-frequency dampener.
9 Interior of inside cone 2 15. The gas-turbine exhaust cone of claim 1, and further
10 Dampening element comprising an annular mounting flange connected to the out
11 Mounting flange 35 side cone at an end area on the inflow-side end area.
12 Sound wave 16. The gas-turbine exhaust cone of claim 1, wherein an
13, 14 Bellows interior of the exhaust cone opens to an exterior only via the
15 Effective length at least one inlet opening.
16 Reflected sound wave 17. The gas-turbine exhaust cone of claim 1, wherein the
17 Radial direction 40 first dampening element has a plate form, with a honeycomb
What is claimed is: structure and acts as a W4 resonator.
1. A gas-turbine exhaust cone, comprising: 18. The gas-turbine exhaust cone of claim 11, and further
a cone shaped outside cone closed in a flow direction; comprising a bellows Supporting at least one of the dampen
an inside cone positioned within the outside cone over at ing elements to at least one of the inside and outside cones.
least part of a length of the exhaust cone; 45 19. The gas-turbine exhaust cone of claim 18 and further
at least one partition wall spirally arranged between the comprising a first bellows Supporting the first dampening
outside cone and the inside cone and connecting the element on the outside cone and a second bellows Supporting
inside cone to the outside cone in a spaced apart manner the second dampening element on the inside cone.
to form an interspace between the outside cone and the 20. A gas-turbine exhaust cone, comprising:
inside cone; 50
a cone shaped outside cone closed in a flow direction;
at least one inlet opening connected to the interspace at an an inside cone positioned within the outside cone over at
inflow side thereof, the interspace opening at an exit side least part of a length of the exhaust cone;
towards an interior of the outside cone; and at least one partition wall spirally arranged between the
a first dampening element positioned within an interior of outside cone and the inside cone and connecting the
the outside cone adjacent to the exit side of the inter inside cone to the outside cone in a spaced apart manner
Space; 55 to form an interspace between the outside cone and the
wherein, the exhaust cone is a closed body other than the at inside cone;
least one inlet opening to prevent exhaust flow through at least one inlet opening connected to the interspace at an
the interspace between the inside and outside cones. inflow side thereof, the interspace opening at an exit side
2. The gas-turbine exhaust cone of claim 1, and further towards an interior of the outside cone; and
comprising a plurality of spaced apart partition walls posi 60 a first dampening element positioned within an interior of
tioned between the outside cone and the inside cone, the the outside cone adjacent to the exit side of the inter
plurality of partition walls being spirally arranged in the Space;
interspace. a second dampening element positioned in an interior of
3. The gas-turbine exhaust cone of claim 2, wherein the at the inside cone at the inflow side.
least one inlet opening includes a plurality of inlet openings in
perforation form.