GB2189845A

GB2189845A - Gas turbine cooling air transferring apparatus

Info

Publication number: GB2189845A
Application number: GB08708767A
Authority: GB
Inventors: James Robert Reigel; Robert James Corsmeier; James Herman Bertke; Dean Thomas Lenahan
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1986-04-30
Filing date: 1987-04-13
Publication date: 1987-11-04
Anticipated expiration: 2007-04-13
Also published as: FR2598179A1; IT8720334A0; GB8708767D0; JPS62276226A; FR2598179B1; DE3713923C2; IT1208035B; GB2189845B; JPH079194B2; DE3713923A1

Description

GB2189845A 1 SPECIFICATION It is an object of the present invention to

provide an improved system for conveying Turbine cooling air transferring apparatus cooling air to the turbine blades of a gas tur bine engine.

The present invention is directed to improve- 70 Another object of the present invention is to ments in gas turbine engines and, more partiprovide an improved system for conveying cularly, to improved cooling of the turbine cooling air to the turbine blades which avoids blades of gas turbine engines. the need for large diameter annular seals and reduces seal air leakage.

BACKGROUND OF THE INVENTION 75 Another object of the present invention is to

Gas turbine engines conventionally comprise provide an improved system for conveying a compressor for pressurizing air to support cooling air to the turbine blades which avoids combustion of fuel to generate a hot gas placing cooling holes or slots directly in the stream. This hot gas stream drives a turbine disk itself thereby maintaining the structural connected to the compressor, and is then uti- 80 strength of the disk.

lized to obtain a propulsive output or a pow- Still another object of the present invention ered shaft output from the engine. In order to is to provide an improved system for convey obtain higher operating efficiencies and power ing cooling air from the high pressure turbine outputs, the hot gas stream, when it passes disk to the low pressure turbine disk which through the turbine, is frequently at a temper- 85 avoids the need for a compressor interstage ature exceeding the physical capabilities of the air supply system and external piping.

materials from which the turbines are fabri- These and other objects of the invention, cated, particularly considering the high together with the features and advantages stresses which are imposed on the turbine rothereof, will become apparent from the follow tor. This has led to many proposals for pro- 90 ing detailed specification when read in con viding cooling systems for the turbine, particu- junction with the accompanying drawings in larly for those portions exposed to the hot which applicable reference numerals have been gas stream. Generally, it has been the practice carried forward.

to direct relatively cool air from the engine compressor to the turbine blades, along a 95 SUMMARY OF THE INVENTION path distinct from the hot gas stream, in order The present invention is for use in a gas to provide the required cooling of the blades. turbine engine which includes a turbine disk One of the problems which is encountered in from which blades project radially into a hot such cooling systems, however, is in the gas stream, a compressor effective for provid mechanism for conveying the cooling air from 100 ing pressurized cooling air and a cooling air the compressor to the turbine which is rotat- transferring apparatus for transferring cooling ing at high speed, and then to the turbine air from the compressor to the turbine. The rotor blades themselves. cooling air transferring means comprises an in One system which has been employed to ducer means, effective for channeling the cool provide air cooling to the turbine blades has 105 ing air in a direction substantially tangentially involved using a large diameter annular seal to the turbine disk and a radial impeller means somewhat forward of the turbine disk to form for receiving the cooling air and conveying it a chamber between the annular seal and the to the blades.

disk to receive cooling air from the compres- In a particular embodiment of the invention, sor and convey it to the turbine blades which 110 the cooling air transferring apparatus includes are mounted on the rim of the turbine disk. a second inducer means which is effective for Systems of this type, however, are inherently channeling a second portion of cooling air in a heavy because of the large diameter of the direction generally tangential to a direction of annular seal and are also subject to substana second turbine disk and a second radial im tially large air leakage. Other systems have in- 115 peller means effective for receiving the second volved the use of annular seals of relatively portion of cooling air and conveying it to the smaller diameter to form correspondingly blades.

smaller annular chambers between the seal and the turbine disk with the cooling air being BRIEF DESCRIPTION OF THE DRAWINGS passed from the smaller annular chamber by 120 The invention, together with further objects means of an impeller mounted on the seal and advantage thereof, is more particularly de along the surface of the disk to the turbine scribed in the following detailed description blades. While systems of this type avoid taken in conjunction with the accompanying some of the leakage encountered using the drawings in which:

larger annular seals, they are still relatively 125 Figure 1 is a crosssection of a gas turbine heavy and require that the annular seal supengine having high and low pressure turbine port a relatively large load in the form of the disks; impeller unit. Figure 2 is a partial view showing the cool ing air transferring apparatus; OBJECTS OF THE INVENTION 130 Figure 3 is a partial cutaway view of the 2 GB2189845A 2 inducer of the invention and a partial cutaway accelerating cooling air 36.

view end-on of the impeller of the invention, Cooling air 36 is then directed through im and peller 46 to the high pressure turbine blades Figure 4 is a partial cutaway view of the 24, as shown in Fig. 2, to provide cooling impeller of the invention. 70 thereto. An annular labyrinth seal 48 is dis posed on the forward side of impeller 46 to DETAILED DESCRIPTION OF THE INVENTION provide an air seal between the stationary

Illustrated in Fig. 1 is an axial flow gas tur- structure 50 and the rotating high pressure bine engine shown generally at 10, including a turbine disk 22 and impeller 46. Impeller 46 is cooling air transferring apparatus generally lo- 75 provided with annular flanged walls 52 and 54 cated at 12, according to one embodiment of at its inner and outer circumference, respec the present invention. The engine 10 includes tively. Flange wall 52 conveniently provides in serial flow relationship fan 14, a compres- attachment of the impeller to the high pres sor 16, a combustor 18, a high pressure tur- sure turbine disk 22 by means of an annular bine 20 including a high pressure turbine disk 80 retaining ring 56, while outer flange wall 54 22 having a plurality of circumferentially fits against disk 22 and the root of the high spaced high pressure turbine blades 24 ex- pressure turbine, blade 24 and provides a seal tending radially outwardly therefrom, and a ing element at its inside diameter.

low pressure turbine 26 including low pres- Referring to Figs. 3 and 4, radial impeller 46 sure turbine disk 28 having a plurality of circonsist essentially of a ring shaped disk hav cumferentially spaced low pressure turbine ing radial channels or passages 58 for increas blades 30 extending radially outwardly there- ing the pressure by centrifugal pumping and from. for conveying the cooling air 36 to the turbine In conventional operation, inlet air 32 is blades 24 (shown in Fig. 2). The radial pass- pressurized by the compressor 16. A major 90 ageways 58 in the impeller 46, which are, of portion of the inlet air 32 is then suitably course, open at both ends to permit passage channeled into the combustor 18 where it is of air, are otherwise fully enclosed. The pass mixed with fuel for generating relatively high ageways 58 may, in fact, be generally elfipti pressure combustion gases which flow to the caL round or otherwise shaped cross section high pressure turbine 20 for providing power 95 passages separated from one another by only to the compressor 16 through an intercon- a thin radial partition or web 60 to maintain necting shaft 34. The combustion gases then the structural strength and form of the impel pass through a low pressure turbine 26 for ler 46. It will, in this regard, be understood providing power to a low pressure compres- that the cross section configuration of the im- sor (not shown) and/or a fan 14 through an 100 peller 46 should provide a passage so that interconnecting shaft 15 and are then dis- the required amount of pressurized cooling air charged from the engine 10. 36 (shown in Fig. 2) is conveyed to the high A portion of the pressurized inlet air 32 that pressure turbine blades 24 (shown in Fig. 2) is discharged from the compressor 16 is used with reasonably low loss in pressure.

for providing pressurized cooling air 36, 105 Referring to Fig. 2, the inducer-impelier com shown in Fig. 2, for cooling the rotor compobination of the present invention, allows the nents which are surrounded by the combus- cooling air pressure at the inducer discharge tion discharge gases. The cooling air 36 is to be reduced below that required without an channeled to the air transferring apparatus 12 impeller 46. This lower pressure provides by an annular inner duct 38 defined by an 110 lower air leakage flow out through the annular inner combustor casing (not shown) and a tur- labyrinth seal 48 with less adverse effect on bine nozzle support structure 40 and 42. turbine efficiency. In addition, the lower indu The air transferring apparatus according to cer discharge pressure allows increased indu one embodiment of the invention, and shown cer pressure ratio and discharge Mach num in Figs. 2 and 3, includes an annular inducer 115 ber. The resultant increase in tangential flow means 44 and is effective for channeling cool- velocity leaving the inducer 44 reduces the ing air 36 in a direction substantially tangential work required to be done by the turbine on to the high pressure turbine disk 22 and into the cooling air 36 in getting the flow into the radial impeller 46 mounted on the high pres- impeller passages 58 (shown in Figs. 3 and sure turbine disk 22 at points A and B. 120 4).

Annular inducer means 44, as shown in Fig. If the tangential velocity of the air leaving 3, includes vanes 76 conventionally sized for the inducer 44 is greater than the speed of accelerating cooling air 36 to a velocity sub- the turbine disk 22, work is done on the disk stantially equal to the tangential velocity of resulting in a turbine efficiency improvement impeller 46. More specifically, the leading and 125 plus an added benefit of reduced cooling air trailing edges 76a and 76b, respectively, of temperature at the entrance to the blades 24.

adjacent vanes 76 define inlet and outlet The inducer-impeller combination also elimi cross-sectional flow areas A1 and A2, respec- nates any mismatch between the disk speed tively. The inlet flow area A1 is suitably sized and the cooling air tangential velocity at the greater than the outlet area A2 for suitably 130 entrance to blades 24, thereby eliminating 3 GB2189845A 3 pressure losses associated with getting flow a compressor interstage air supply system and into blades 24. external piping.

In an alternative embodiment of the turbine The impeller of this invention also avoids cooling air transferring apparatus 12, as prior art practices of providing cooling holes shown in Fig. 2, a second portion 36A of the 70 or slots directly in the turbine disk itself, pressurized cooling air 36 is directed to a de- which weaken the structure, and, at the same swirler 62 in order to aerodynamically change time, avoids the inefficiency of mounting the the direction of flow of the cooling air 36A impeller structure or its equivalent on a sepa and guide the air into annulus 64 located in- rate member with only one disk-like or flanged ward of the high pressure turbine disk 22. 75 wall structure. The present invention therefore The deswirler 62 is directly attached to the offers the substantial advantage of increased interconnecting shaft 34 so it rotates in ex- engine performance, greater structural actly the same manner. This feature enables strength, and reduced air leakage.

the deswirler 62 to reduce the tangential velo- It will be clear to those skilled in the art city of cooling air 36A to match the tangential 80 that the present invention is not limited to the velocity of high pressure turbine disk 22 while specific embodiments described and illustrated maintaining its angular momentum. Cooling air herein.

36A is then directed through a series of holes It will be understood that the dimensions to a second rotating inducer 66. Second and proportional and structural relationships inducer 66 is effective for directing cooling air 85 shown in the drawings are by way of example 36A in a direction substantially tangential to only, and these illustrations are not to be low pressure turbine disk 28. Inducer 66 is taken as the actual dimensions or proportional also effective for extracting some of the pres- structural relationships used in the turbirte sure energy contained in cooling air 36A and cooling air transferring means of the present converting it into work to help drive the high 90 invention.

pressure turbine disk 22. By transferring some

Claims

of the energy of the air to the turbine, a re- CLAIMS duction in the

cooling air temperature is ac- 1. In a gas turbine engine including a tur complished. Reduced cooling air temperature bine disk from which blades project radially permits a reduction in cooling airflow, thereby 95 into a hot gas stream; a compressor effective improving turbine efficiency and engine per- for providing pressurized cooling air; and a formance. cooling air transferring apparatus for trans Between second inducer 66 and the inlet to ferring cooling air from the compressor to the a second annular impeller 68, the angular mo- turbine disk, separate from the hot gas mentum of cooling air 36A is generally main- 100 stream, wherein the cooling air transferring tained while the tangential velocity decreases means comprises in combination:

until reaching the second annular impeller 68, an inducer means effective for channeling where the tangential velocity of cooling air said cooling air in a direction substantially tan 36A and the low pressure turbine disk 28 are gentially to said turbine disk; and substantially equal. 105 a radial impeller means for receiving said Impefler 68 is mounted on the low pressure cooling air and conveying it to said blades.

disk 28 and is provided with passages 70
2. The cooling air transferring apparatus of through which cooling air 36A passes to the claim 1 wherein said impeller means is sup rim of the low pressure turbine disk 28 and ported on said turbine disk.

then to low pressure turbine blades 30. A 110
3. The cooling air transferring apparatus of forward facing seal 72 is provided on the forclaim 1 wherein said impeller means com ward side of the impelier 68 to engage the prises a plurality of radial passages for receiv seal mounted between the high pressure tur- ing said cooling air and conveying it to said bine disk 22 and the low pressure turbine disk blades.

28. 115
4. The cooling air transferring apparatus of It will be appreciated, that the use of the claim 3 wherein said radial passages are en radial impeller of the present invention has the closed within said impeller.

advantage of avoiding any need for large dia-
5. The cooling air transferring apparatus of meter, heavy seals and minimizes air leakage claim 1 wherein said inducer means comprises by placing the seal provisions relatively close 120 a plurality of circumferentially spaced stator to the central, concentric rotating shafts of the vanes effective for channeling said cooling air engine. In addition, the use of an inducer-im- in a direction substantially tangential to said peller combination is effective for directing rotor component.

cooling air to rotating turbine blades without
6. The cooling air transferring apparatus of placing cooling holes or slots directly in the 125 claim 1 wherein said impeller means includes rotor disk itself, thereby maintaining the struc- an annular air seal.

tural strength of the disk. Furthermore, the in-
7. In a gas turbine engine including a com ducer-impeller combination of the low pressure pressor effective for providing pressurized turbine allows cooling air to be conveyed to cooling air; first and second turbine disks con the low pressure turbine without the need for 130 nected to first and second coaxially spaced 4 GB2189845A 4 shafts interconnecting said compressor to said described with reference to and as illustrated turbine disks; and a cooling air transferring in the drawings.

apparatus for transferring cooling air from the Printed for Her Majesty's Stationery Office compressor to the turbine disks separate from by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987.

the hot gas stream, wherein the cooling air Published at The Patent Office, 25 Southampton Buildings, transferring means comprises in combination: London, WC2A 'I AY, from which copies may be obtained.

a inducer means effective for channeling a first portion of said cooling air substantially tangential to said first turbine disk and for channeling a second portion of said cooling air to a deswirler means; a first radial impeller means effective for receiving said first portion of said cooling air and conveying it to said blades; and a second radial impeller means effective for receiving said second portion of said cooling air and conveying it to said blades.
8. The cooling air transferring apparatus of claim 7 wherein said first impeller means is supported on said first turbine disk and said second impeller means is supported on said second turbine disk.
9. The cooling air transferring apparatus of claim 7 wherein said first and second impeller means each comprise a plurality of radial pas7 sages for receiving said cooling air and conveying it to said respective blades.
10. The cooling air transferring apparatus of claim 9 wherein said radial passages are en- closed within said first and second impeller means.
11. The cooling air transferring apparatus of claim 7 wherein said first inducer means comprises a plurality of circumferentially spaced stator vanes effective for channeling said cooling air in a direction substantially tangential to said first turbine disk.
12. The cooling air transferring apparatus of claim 7 wherein said deswirler means com- prises a plurality of circumferentially spaced stator vanes effective for channeling said second portion of said cooling air to an annulus and in a direction generally tangential to a direction of rotation of said first turbine disk. 45
13. The cooling air transferring apparatus of claim- 7 wherein said second portion of said cooling air is directed through a second inducer means to said second annular impeller.
14. The cooling air transferring apparatus of claim 13 wherein said second inducer means is effective for extracting some of the pressure energy contained in said second portion of said cooling air and for converting said energy into work to help drive said first tur- bine disk.
15. The cooling air transferring apparatus of claim 13 wherein said second inducer means is effective for directing said second portion of said cooling air in a direction sub- stantially tangential to said second turbine disk.
16. The cooling air transferring apparatus of claim 13 wherein said second inducer means is rotating with said first turbine disk.
17. Apparatus substantially as hereinbefore