Claims:1. A turbomachine (10) comprising:
a combustor (14);
a compressor (12) comprising a discharge casing (22), wherein the compressor (12) is in fluid communication with the combustor (14) via a first flow path (30) defined by a portion of the discharge casing (22);
a turbine (16) coupled to the combustor (14) and the compressor (12), wherein the compressor (12) is in fluid communication with the turbine (16) via a second flow path (34) defined between the portion of the discharge casing (22) and a shaft (34), and wherein the shaft (34) is coupled to the turbine (16) and the compressor (12); and
a plurality of heat dissipating elements (18) coupled to the portion of the discharge casing (22), wherein each of the plurality of heat dissipating elements (18) extends between the first flow path (30) and the second flow path (34) through the portion of the discharge casing (22).

2. The turbomachine (10) of claim 1, wherein the plurality of heat dissipating elements (18) is configured to transfer at least a portion of heat from a bypass compressed fluid (36b) in the second flow path (34) to a main compressed fluid (36a) in the first flow path (30).

3. The turbomachine (10) of claim 1, wherein the first flow path (30) comprises a compressor discharge cavity (94) located proximate to the combustor (14) and the second flow path (34) comprises a wheel space cavity (96) located proximate to a rotor (38) of the turbine (16).

4. The turbomachine (10) of claim 3, wherein each of the plurality of heat dissipating elements (18) extends between the wheel space cavity (96) and the compressor discharge cavity (94).

5. The turbomachine (10) of claim 3, further comprising a labyrinth seal (68) disposed in the second flow path (34) upstream of the wheel space cavity (96), and wherein the labyrinth seal (68) is configured to regulate a flow of a bypass compressed fluid (36b) from the compressor (12).

6. The turbomachine (10) of claim 1, wherein the heat dissipating elements of the plurality of heat dissipating elements (18) are spaced apart from each other along an axial direction (150) and a circumferential direction (138) of the compressor (12).

7. The turbomachine (10) of claim 1, wherein the plurality of heat dissipating elements (221) comprises a first heat dissipating element (221a) having a first length (L1) and a second heat dissipating element (221b) having a second length (L2) different from the first length (L1).

8. The turbomachine (10) of claim 1, wherein at least one of the plurality of heat dissipating elements (18) comprises a heat pipe (21).

9. The turbomachine (10) of claim 1, wherein at least one of the plurality of heat dissipating elements (18) comprises a vapor chamber (121).

10. A heat exchange system (11) for a turbomachine (10) comprising a compressor (12) and a turbine (16), wherein the heat exchange system (11) comprises:
a flow path (34) defined between a portion of a discharge casing (22) of the compressor (12) and a shaft (24), wherein the shaft (24) is coupled to the turbine (16) and the compressor (12); and
a plurality of heat dissipating elements (18) coupled to the portion of the discharge casing (22) and configured to transfer at least a portion of heat away from a bypass compressed fluid (36b) of the compressor (12) in the flow path (34).

11. The heat exchange system (11) of claim 10, wherein the plurality of heat dissipating elements (18) is configured to transfer the heat from the bypass compressed fluid (36b) to a main compressed fluid (36a) of the compressor (12).

12. The heat exchange system (11) of claim 10, wherein the heat dissipating elements of the plurality of heat dissipating elements (18) are spaced apart from each other along an axial direction (150) and a circumferential direction (138) of the compressor (12).
13. The heat exchange system (11) of claim 10, wherein the plurality of heat dissipating elements (221) comprises a first heat dissipating element (221a) having a first length (L1) and a second heat dissipating element (221b) having a second length (L2) different from the first length (L1).

14. The heat exchange system (11) of claim 10, wherein at least one of the plurality of heat dissipating elements (18) comprises a heat pipe (21).

15. The heat exchange system (11) of claim 10, wherein at least one of the plurality of heat dissipating elements (18) comprises a vapor chamber (121).

16. A method (300) comprising:
discharging a main compressed fluid from a compressor to a combustor along a first flow path defined by a portion of a discharge casing of the compressor (302);
releasing a bypass compressed fluid from the compressor to a turbine along a second flow path defined between the portion of the discharge casing and a shaft, wherein the shaft is coupled to the compressor and the turbine (304); and
transferring at least a portion of heat from the bypass compressed fluid to the main compressed fluid via a plurality of plurality of heat dissipating elements coupled to the portion of the discharge casing (306).

17. The method (300) of claim 16, wherein transferring at least a portion of the heat comprises dissipating heat from the bypass compressed fluid in a wheel space cavity to the main compressed fluid in a compressor discharge cavity, wherein the compressor discharge cavity is located inside the first flow path and proximate to the combustor, and wherein the wheel space cavity is located inside the second flow path and proximate to a rotor of the turbine.

18. The method (300) of claim 17, further comprising regulating a flow of the bypass compressed fluid using a labyrinth seal disposed in the second flow path upstream of the wheel space cavity.

19. The method (300) of claim 16, wherein at least one of the plurality of heat dissipating elements comprises a heat pipe.

20. The method (300) of claim 16, wherein least one of the plurality of heat dissipating elements comprises a vapor chamber.
, Description:[0001] Embodiments of the disclosed technique relate to turbomachines, and more specifically to a heat exchange system for regulating heat in a wheel space cavity of a turbomachine.
[0002] Turbomachine, such as a gas turbine engine, includes a compressor, a combustor, and a turbine. The compressor is fluidly coupled to the combustor via a first flow path and to a first stage of the turbine via a second flow path. Typically, the turbine includes rotors and stators, and each rotor includes a shank that is flanked on upstream and downstream ends by shrouds of the stators. The shank includes an angel wing and the shroud includes a rub strip. The angel wing is disposed facing the rub strip to form a seal therebetween. In such a configuration, the second flow path includes a wheel space cavity located proximate to the angel wing and the rub strip belonging to a first stage of the turbine.
[0003] During operation, the compressor is configured to generate compressed fluid and discharge main compressed fluid to the combustor via the first flow path. The compressor is further configured to discharge bypass compressed fluid to the turbine via the second flow path. Typically, the bypass compressed fluid is used to regulate temperature in the wheel space cavity and cool the rub strip and the angel wing. The bypass flow then purges into the turbine flow to avoid hot gas ingestion into the wheel space. Generally, compressor efficiency depends on an amount of the compressed fluid been discharged to the combustor rather than bypassed to the turbine. However, the amount of the bypass compressed fluid may not be reduced as the temperature of the bypass compressed fluid in the wheel space cavity raises above the temperature of the main compressed fluid, because of windage heating in the second flow path. Further, the raise in the temperature of the bypass compressed fluid may inadvertently impact the life of the rotor and the angel wing. Accordingly, there is a need for a heat exchange system and an associated method for regulating temperature of the bypass compressed fluid in the wheel space cavity.
BRIEF DESCRIPTION
[0004] In accordance with one embodiment, a turbomachine is disclosed. In accordance with aspects of the disclosed technique, the turbomachine includes a combustor, a compressor, a turbine, and a plurality of heat dissipating elements. The compressor includes a discharge casing, where the compressor is in fluid communication with the combustor via a first flow path defined by a portion of the discharge casing. The turbine is coupled to the combustor and the compressor, where the compressor is in fluid communication with the turbine via a second flow path defined between the portion of the discharge casing and a shaft, and where the shaft is coupled to the turbine and the compressor. The plurality of heat dissipating elements coupled to the portion of the discharge casing, where each of the plurality of heat dissipating elements extends between the first flow path and the second flow path through the portion of the discharge casing.
[0005] In accordance with another embodiment, a heat exchange system for a turbomachine, is disclosed. The turbomachine includes a compressor and a turbine. In accordance with aspects of the disclosed technique, the heat exchange system includes a flow path defined between a portion of a discharge casing of the compressor and a shaft, where the shaft is coupled to the turbine and the compressor. Further, the heat exchange system includes a plurality of heat dissipating elements coupled to the portion of the discharge casing and configured to transfer at least a portion of heat away from a bypass compressed fluid of the compressor in the flow path.
[0006] In accordance with yet another embodiment, a method for transferring heat away from a wheel space cavity is disclosed. In accordance with aspects of the disclosed technique, the method includes discharging a main compressed fluid from a compressor to a combustor along a first flow path defined by a portion of a discharge casing of the compressor. Further, the method includes releasing a bypass compressed fluid from the compressor to a turbine along a second flow path defined between the portion of the discharge casing and a shaft, where the shaft is coupled to the compressor and the turbine. The method further includes transferring at least a portion of heat from the bypass compressed fluid to the main compressed fluid via a plurality of plurality of heat dissipating elements coupled to the portion of the discharge casing.
DRAWINGS
[0007] These and other features and aspects of embodiments of the disclosed technique will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
[0008] FIG. 1 is a cross-sectional view of a portion of a turbomachine, in accordance with aspects of the disclosed technique;
[0009] FIG. 2 is a schematic cross-sectional view of a portion of the turbomachine of FIG.1 including a heat exchange system, in accordance with aspects of the disclosed technique;
[0010] FIG. 3 is a schematic cross-sectional view of a heat pipe disposed in a portion of a discharge casing, in accordance with aspects of the disclosed technique;
[0011] FIG. 4 is a schematic cross-sectional view of a vapor chamber disposed in another portion of a discharge casing, in accordance with aspects of the disclosed technique;
[0012] FIG. 5 is a schematic cross-sectional view of a plurality of heat dissipating elements disposed in a portion of a discharge casing, in accordance with aspects of the disclosed technique; and
[0013] FIG. 6 is a flow diagram of an exemplary method for regulating temperature in a wheel space cavity of a turbomachine, in accordance with one exemplary embodiment.
DETAILED DESCRIPTION
[0014] Embodiments discussed herein disclose a plurality of heat dissipating elements for regulating temperature of a bypass compressed fluid in a wheel space cavity of a turbomachine, such as a gas turbine engine. In certain embodiments, the plurality of heat dissipating elements is disposed proximate to an intra-stage seal of the gas turbine engine. Specifically, the plurality of heat dissipating elements is located between the intra-stage seal and a labyrinth seal of the gas turbine engine. In some of these embodiments, the gas turbine engine further includes a combustor, a compressor, and a turbine. The combustor is in fluid communication with the compressor via a first flow path defined by a portion of a discharge casing of the compressor. The turbine is coupled to the compressor via a shaft, and in fluid communication with the combustor. In certain embodiments, the shaft may be a mid-shaft or a shaft joint fastened at both ends respectively to the compressor shaft and a turbine shaft. In certain embodiments, the turbine is configured to drive the compressor via the shaft. Further, the compressor is in fluid communication with the turbine via a second flow path defined between the portion of the discharge casing and the shaft. The plurality of heat dissipating elements is coupled to the portion of the discharge casing. In some embodiments, each of the plurality of heat dissipating elements extends between the first flow path and the second flow path through the portion of the discharge casing. In one embodiment, the first flow path includes a compressor discharge cavity located proximate to the combustor and the second flow path includes a wheel space cavity located proximate to a rotor of the turbine.
[0015] During operation, the compressor is configured to discharge main compressed fluid to the combustor along the first flow path. The compressor is further configured to release bypass compressed fluid to the turbine along the second flow path. In such an embodiment, the plurality of heat dissipating elements is configured to transfer at least a portion of heat from the bypass compressed fluid in the wheel space cavity to the main compressed fluid in the compressor discharge cavity, thereby effectively regulating temperature of the bypass compressed fluid in the wheel space cavity. Thus, employment of the plurality of heat dissipating elements may allow the compressor to reduce an amount of the bypass compressed fluid released to the turbine. Consequently, increasing an amount of the main compressed fluid released to the combustor and efficiency of the compressor. Further, effective regulation of the temperature in the wheel space cavity may allow the compressor to optimize a compression ratio of the fluid. It should be noted herein that the term “compression ratio” refers to a ratio of an absolute stage discharge pressure to the absolute stage suction pressure. In certain embodiments, the optimal compression ratio may be in a range from about 8:1 to about 14:1. Also, the plurality of heat dissipating elements may indirectly improve a shelf life of an angel wing and a rub-strip of the intra-stage seal.
[0016] In some other embodiments, the plurality of heat dissipating elements is part of a heat exchange system. In such embodiments, the heat exchange system is used in the turbomachine for effectively regulate temperature in the wheel space cavity. In one embodiment, the heat exchange system includes a flow path defined between a portion of the discharge casing of the compressor and the shaft. During operation, the plurality of heat dissipating elements is coupled to the portion of the discharge casing and configured to transfer at least a portion of heat away from the bypass compressed fluid of the compressor in the flow path.
[0017] FIG. 1 illustrates a cross-sectional view of a portion of a turbomachine 10 in accordance with one exemplary embodiment of the disclosed technique. The turbomachine 10 includes a compressor 12, a combustor 14, and a turbine 16, and a plurality of heat dissipating elements 18. The compressor 12 includes a plurality of compressor blades 20 and a discharge casing 22. The compressor 12 is in fluid communication with the combustor 14 via a first flow path 30 defined by a portion of the discharge casing 22.
[0018] The turbine 16 is coupled to the compressor 12 via a shaft 24, such as a mid-shaft. In the illustrated embodiment, the shaft 24 includes a compressor component 24a and a turbine component 24b coupled to each other via a marriage joint 25. The compressor component 24a is coupled to at least one compressor blade of the plurality of compressor blades 20. Further, the turbine 16 is in fluid communication with the compressor 12 and the combustor 14. Specifically, the compressor 12 is a fluid commination with the turbine 16 via a second flow path 34 defined between the portion of the discharge casing 22 and a shaft 24 bypassing the combustor 14. The turbine 16 includes a plurality of rotors 38, 40 connected to the shaft 24 for rotation therewith. The turbine 16 further includes a plurality of stators 54, 56 (also referred to as “stator blades”) coupled to a casing 70. The stator 54 is further coupled to the portion of the discharge casing 22 of the compressor 12. Each of the plurality of stators 54, 56 and each of the plurality of rotors 38, 40 are disposed alternately. Each pair of mutually adjacent rotors 38, 40 and stators 54, 56 defines a stage to form a plurality of stages of the turbine 16. In the illustrated embodiment, the turbine 16 includes two-stages, where a first stage is represented by the stator 54 and the rotor 38 and a second stage is represented by the stator 56 and the rotor 40. The turbine 16 further includes a spacer wheel 62 which is coupled to and disposed between the rotors 38, 40.
[0019] The plurality of rotors 38, 40 includes a plurality of rotor blades 46, 48, respectively. In the illustrated embodiment, the rotor 38 is coupled to the turbine component 24b of the shaft 24. Further, the plurality of rotors 38, 40 includes a plurality of shanks 72, 74, respectively. Each shank 72, 74 is coupled to a corresponding rotor disk of a plurality of rotor disks (not labeled in FIG. 1). Each of the plurality of rotors 38, 40 further includes at least two angel wings. In the illustrated embodiment, the rotor 38 includes angel wings 80, 82 and the rotor 40 includes angel wings 84, 86. The angel wings 80, 82 are coupled to the shank 72 and the angel wings 84, 86 are coupled to the shank 74. Each of the plurality of stators 54, 56 includes at least one rub strip. In the illustrated embodiment, the stator 54 includes the rub strip 88 and the stator 56 includes rub strips 90, 92. The rub strip 88 is coupled to discharge casing 22 coupled to the stator 54, and the rub strips 90, 92 are coupled to a stator diaphragm 98 of the stator 56.
[0020] The angel wing 80 is disposed facing the rub strip 88 to form an intra-stage seal 110 between the discharge casing 22 and the rotor 38. Similarly, the angel wings 82, 84 are disposed facing the respective rub strips 90, 92 to form an inter-stage seal 112 between the stator diaphragm 98 and the rotor 40.
[0021] The first flow path 30 includes a compressor discharge cavity 94 located proximate to the combustor 14. Specifically, the compressor discharge cavity 94 is formed between the stator 54, the portion of the discharge casing 22, and the combustor 14. The second flow path 34 includes a wheel space cavity 96 located proximate to the rotor 38 of the turbine 16. Specifically, the wheel space cavity 96 is formed between the portion of the discharge casing 22, the shank 72, and the turbine component 24b of the shaft 24. In one or more embodiments, the plurality of heat dissipating elements 18 is coupled to the portion of the discharge casing 22. Each of the plurality of heat dissipating elements 18 extends between the first flow path 30 and the second flow path 34 through the portion of the discharge casing 22. Specifically, each of the plurality of heat dissipating elements 18 extends between the wheel space cavity 96 and the compressor discharge cavity 94. Further, the plurality of heat dissipating elements 18 is disposed proximate to the angel wings 80 and the rub strip 88. In one embodiment, at least one of the plurality of heat dissipating elements 18 is a heat pipe. In some embodiments, at least one of the plurality of heat dissipating elements 18 is a vapor chamber.
[0022] The turbomachine 10 further includes a labyrinth seal 68 disposed in at least one pre-defined location of the turbine 16. In one embodiment, the pre-defined location is in the second flow path 34 extending from the compressor 12 to the turbine 16. In the illustrated embodiment, the labyrinth seal 68 is disposed upstream of the wheel space cavity 96. Specifically, the labyrinth seal 68 is disposed upstream relative to the plurality of heat dissipating elements 18 and the intra-stage seal 110.
[0023] During operation, the compressor 12 is configured to receive a fluid, such as, air and compress the received fluid to generate compressed fluid 36. The combustor 14 is configured to receive a main compressed fluid 36a from the compressor 12 and a fuel 19, such as a natural gas, from fuel injectors (not shown in FIG. 1). The terms “main compressed fluid” as used in the context refers to a major portion or fraction of the compressed fluid 36 discharged from the compressor 12. The combustor 14 is further configured to burn a mixture of the fuel 19 and the main compressed fluid 36a within a combustion zone (not labeled in FIG. 1) to generate an exhaust gas stream 28. The turbine 16 is configured to receive the exhaust gas stream 28 from the combustor 14 along a third flow path 26. The turbine 16 is further configured to expand the exhaust gas stream 28 through multiple stages of the turbine 16 to convert energy present in the exhaust gas stream 28 to work. In one or more embodiments, the main compressed fluid 36a is directed along the first flow path 30. In such embodiments, the main compressed fluid 36a is temporarily stored in the compressor discharge cavity 94 to reduce swirl in the main compressed fluid 36a before the main compressed fluid 36a is discharged to the combustor 14.
[0024] In one embodiment, the compressor 12 is configured to release a bypass compressed fluid 36b to the turbine 16 via the second flow path 34. The terms “bypass compressed fluid” as used in the context refers to a minor portion or fraction of the compressed fluid 36 discharged from the compressor 12. Specifically, the bypass compressed fluid 36b is directed to the wheel space cavity 96 through the labyrinth seal 68. Further, the bypass compressed fluid 36b is directed from the wheel space cavity 96 to the rotor blade 46 through the intra-stage seal 110. In one or more embodiments, the labyrinth seal 68 is configured to regulate a flow of the bypass compressed fluid 36b from the compressor 12. Similarly, the intra-stage seal 110 is configured to regulate the flow of the bypass compressed fluid 36b from the wheel space cavity 96. In one or more embodiments, the labyrinth seal 68 includes teeth formed on the stationary or rotatable components, thereby obstructing flow of the bypass compressed fluid 36b and regulating excess flow of the bypass compressed fluid 36b through the second flow path 34. In some embodiments, temperature of the bypass compressed fluid 36b flowing along the second flow path 34 is increased due to windage heating of the bypass compressed fluid 36b in the labyrinth seal 68 and friction heating of the bypass compressed fluid 36b downstream of the marriage joint 25. In such embodiments, the temperature of the bypass compressed fluid 36b in the wheel space cavity 96 is substantially higher than temperature of the main compressed fluid 36a in the compressor discharge cavity 94. In accordance with one or more embodiments of the disclosed technique, the plurality of heat dissipating elements 18 is configured to transfer at least a portion of heat from the bypass compressed fluid 36b in the second flow path 34 to the main compressed fluid 36a in the first flow path 30 to regulate the temperature in the wheel space cavity 96.
[0025] In one or more embodiments, the plurality of heat dissipating elements 18 may regulate the temperature of the bypass compressed fluid 36b, thereby allowing the compressor 12 to reduce the amount of the bypass compressed fluid 36b released to the turbine 16 and increase the amount of the main compressed fluid 36a released to the combustor 14, thus increasing efficiency of the compressor 12. Further, effective regulation of the temperature in the wheel space cavity 96 may allow the compressor 12 to optimize the compression ratio of the fluid. Also, the plurality of heat dissipating elements 18 may indirectly improve a shelf life of the angel wings 80 and the rub strips 88 of the intra-stage seal 110. In one or more embodiments, temperature reduction of about 20 degrees Fahrenheit in the wheel space cavity 96 allows the compressor 12 to reduce the amount of the bypass compressed fluid by about 20 percent.
[0026] FIG. 2 illustrates a schematic cross-sectional view of a portion of the turbomachine including a heat exchange system 11 in accordance with the exemplary embodiment of FIG. 1. The heat exchange system 11 includes the second flow path 34 (also referred to as a “flow path”) defined between the portion of the discharge casing 22 of the compressor and the shaft 24. It should be noted herein that only a portion of the shaft 24 is shown in FIG. 2. In one embodiment, the shaft 24 is coupled to the rotor 38. The heat exchange system 11 further includes the plurality of heat dissipating elements 18 disposed proximate to the intra-stage seal 110. The portion of the discharge casing 22 may further include the rub strip 88. The rotor 38 may include the angel wing 80. In such embodiments, the rub strip 88 is disposed facing the angel wing 80 to form the intra-stage seal 110 there-between. The second flow path 34 includes the wheel space cavity 96 defined between a peripheral side portion 92a of the discharge casing 22, a peripheral side portion 38a of the shaft 24, and a peripheral side portion 38b of the rotor 38.
[0027] The plurality of heat dissipating elements 18 is coupled to the portion of the discharge casing 22. Further, the heat dissipating elements of the plurality of heat dissipating elements 18 are spaced apart from each other along an axial direction 150 and a circumferential direction 138 of the compressor. In one embodiment, at least one of the plurality of heat dissipating elements 18 is a heat pipe. In some other embodiments, at least one of the plurality of heat dissipating elements 18 is a vapor chamber. In one or more embodiments, the heat pipe and/or the vapor chamber may include an evaporator portion disposed in the wheel space cavity 96, a condenser portion disposed in the compressor discharge cavity 94, and a transport portion extending through the discharge casing 22 and connecting the evaporator and condenser portions.
[0028] The discharge casing 22 may further include a bore plug 89 disposed upstream relative to the plurality of heat dissipating elements 18. In the illustrated embodiment, the bore plug 89 is a through channel connecting the first flow path 30 to the second flow path 34. In certain embodiments, the bore plug 89 may include a valve (not shown) configured to control discharge of the bypass compressed fluid 36b from the second flow path 34 to the first flow path 30 during certain transient operating condition. In one or more embodiments, the transient operating condition may include critical operating temperature of the bypass compressed fluid 36b in the wheel space cavity 96. During operation, the plurality of heat dissipating elements 18 transfers at least a portion of heat away from the bypass compressed fluid 36b in the wheel space cavity 96. Specifically, the heat dissipating elements 18 transfers the heat from the bypass compressed fluid 36b to the main compressed fluid 36a in the compressor discharge cavity 94.
[0029] FIG. 3 illustrates a cross-sectional view of a heat pipe 21 in accordance with one exemplary embodiment of the disclosed technique. In the illustrated embodiment, the heat pipe 21 is disposed along a through-hole 22a formed in the portion of the discharge casing 22. The heat pipe 21 includes an evaporator portion 21a located in the wheel space cavity 96, a condenser portion 21b located in the compressor discharge cavity 94, and a transport portion 21c extending through the discharge casing 22. Further, the evaporator portion 21a and the condenser portion 21b may be clamped to the discharge casing using appropriate clamping techniques, such as clamps 23a, 23b, bolts, or the like. The heat pipe 21 may be flexible in nature, thereby allowing the heat pipe to be inserted through the discharge casing 22 and bent along respective peripheral side portions 92a, 92b of the discharge casing 22. In such embodiments, ends of the heat pipe 21 may be hermetically sealed using appropriate sealing techniques, thereby concealing working fluid within the heat pipe 21.
[0030] In one or more embodiments, the heat pipe 21 may include a casing and a wick disposed within the casing. Further, the heat pipe 21 may include a sealed chamber enclosed by the wick and a working fluid filled within the sealed chamber. In certain embodiments, the working fluid filled within the heat pipe 21 may include a liquid metal, such as sodium, potassium, and the like. In such embodiments, the evaporator portion 21a is configured to absorb heat from the bypass compressed fluid 36b by evaporating the working fluid. The condenser portion 21b is configured to release heat to the main compressed fluid 36a by condensing the working fluid. The transport portion 21c is configured to transport a vaporized working fluid from evaporator portion 21a to the condenser portion 21b and the condensed working fluid from the condenser portion 21b to the evaporator portion 21a via the wick. In one or more embodiments, the heat pipe 21 may be fabricated using a material having high thermal conductivity. In such embodiments, the material may include copper or aluminum nitrate, for example. In certain embodiments, the heat pipe 21 may be a looped heat pipe. In such embodiments, the heat pipe 21 may be indifferent to gravity, thereby allowing the condenser portion 21b to recirculate the condensed working fluid to the evaporator portion 21a against the gravity, and through the wick using capillary action.
[0031] FIG. 4 illustrates a cross-sectional view of a vapor chamber 121 in accordance with one exemplary embodiment of the disclosed technique. In the illustrated embodiment, the vapor chamber 121 is disposed along two through-holes 122a, 122b formed in the portion of the discharge casing 22. The vapor chamber 121 includes an evaporator portion 121a located in the wheel space cavity 96, a condenser portion 121b, 121c located in the compressor discharge cavity 94, and a transport portion 121d, 121e extending through the discharge casing 22 via through-holes 122a, 122b respectively. The evaporator portion 121a extends along the peripheral side portion 92a of the discharge casing 22 and the condenser portions 121b, 121c extends in opposite direction along the peripheral side portion 92b of the discharge casing 22. The condenser portions 121b, 121c may be coupled to the discharge casing 22 using appropriate clamping techniques, such as clamps 123a, 123b, bolts, or the like. Similar to the heat pipe 21 of the embodiment of FIG. 3, the vapor chamber 121 includes a chamber casing and a wick disposed within the chamber casing. The vapor chamber further includes a working fluid disposed within the hermetically sealed chamber casing. In such embodiments, the vapor chamber is configured to absorb heat from the bypass compressed fluid 36b in the wheel space cavity 96 through the working fluid and transfer the heat to the main compressed fluid 36a in the compressor discharge cavity 94. Unlike the heat pipe 21 of the embodiment of FIG. 3, the vapor chamber 121 is configured to transfer heat in multiple directions, such as along the circumferential direction 138, the axial direction 150, and a radial direction 160 of the compressor. The vapor chamber 121 may be fabricated using a material having high thermal conductivity. In some such embodiments, the material may include copper or aluminum nitrate, for example.
[0032] FIG. 5 illustrates a schematic cross-sectional view of a plurality of heat dissipating elements 221 in accordance with one exemplary embodiment of the disclosed technique. In the illustrated embodiment, the heat dissipating elements of the plurality of heat dissipating elements 221 are spaced apart from each other along a circumferential direction 138 of the compressor. Further, each of the plurality of heat dissipating elements 221 is coupled to the portion of the discharge casing 222.
[0033] In one embodiment, at least one of the plurality of heat dissipating elements 221 is a heat pipe or a vapor chamber or a combination thereof. The plurality of heat dissipating elements 221 extends between a wheel space cavity 296 and a compressor discharge cavity 294 and configured to dissipate heat from the bypass compressed fluid 236b to the main compressed fluid 236a. Further, the plurality of heat dissipating elements 221 includes a first heat dissipating element 221a having a first length “L1” and a second heat dissipating element 221b having a second length “L2” different from the first length “L1”. In one or more embodiments, the length of the plurality of heat dissipating elements may gradually decrease from top section 222a to the bottom section 222b of the discharge casing 222. Thus, allowing the plurality of heat dissipating elements 221 to easily transfer a condensed fluid from a condenser portion to an evaporator portion against the gravity.
[0034] In one embodiment, the plurality of heat dissipating elements 221, for example, the heat pipes disposed at the top section 222a of the discharge casing 222 have a low thermal conductivity in comparison with the heat pipes disposed at the bottom section 222b of the discharge casing 222, to enable a uniform heat transfer across the discharge casing 222 irrespective of the varied length of the plurality of heat dissipating elements 221. In some embodiments, the heat pipes with a relatively low thermal conductivity may be obtained by varying capillary resistance of the respective heat pipe. In some embodiments, the capillary resistance of the heat pipes may be changed by changing material of the wick in the corresponding heat pipe. For example, the heat pipes disposed at the top section 222a of the discharge casing 222 may include the relatively low thermal conductivity in comparison with the heat pipes disposed at the bottom section 222b of the discharge casing 222. In some embodiments, the material of the wick may include copper, aluminum nitrate, or the like. In some other embodiments, the capillary resistance of the heat pipes may be changed by varying thickness of the wick in the corresponding heat pipe. For example, the heat pipes disposed at the top section 222a of the discharge casing 222 may have a relatively high resistance wick in comparison with the heat pipes disposed at the bottom section 222b of the discharge casing 222.
[0035] Although not illustrated, in certain embodiments, the heat pipes disposed around the discharge casing 222 may have a uniform length. In such an embodiment, the heat pipes may be configured to provide a uniform heat transfer rate from the wheel space cavity 296 and the compressor discharge cavity 294 by varying thermal conductivity of the respective heat pipe. For example, the heat pipes disposed at the top section 222a may have a relative high thermal conductivity material in comparison with the heat pipes disposed at the bottom section 222b. Thus, the heat pipes may be indifferent to gravity, and thereby prevent the possibility of distorting or bulging the discharge casing 222 due to varied heat transfer rate across the discharge casing 222.
[0036] FIG. 6 is a flow diagram of a method 300 for regulating temperature in a wheel space cavity of a turbomachine in accordance with one exemplary embodiment.
[0037] The method 300 includes a step 302 of discharging main compressed fluid from a compressor to a combustor along a first flow path defined by a portion of a discharge casing of the compressor. In certain embodiments, the compressor is configured to discharge a substantially large portion of the compressed fluid as the main compressed fluid to the combustor. The combustor is configured to burn a mixture of a fuel and the main compressed fluid to generate an exhaust gas stream. The turbine is configured to receive the exhaust gas stream and expand the exhaust gas stream through a plurality of stages of the turbine to convert energy in the exhaust gas stream to work.
[0038] Further, the method 300 includes a step 304 of releasing bypass compressed fluid from the compressor to the turbine along a second flow path defined between the portion of the discharge casing and a shaft. The bypass compressed fluid may be used for cooling one or more components, such as, angel wings and/or rub strips of an intra-stage seal, or to purge into the main gas path of the turbine to avoid hot gas ingestion. Further, the method 300 includes a step 306 of transferring at least a portion of heat from the bypass compressed fluid to the main compressed fluid via a plurality of heat dissipating elements coupled to the portion of the discharge casing. In certain embodiments, the plurality of heat dissipating elements is configured to dissipate the heat from the bypass compressed fluid in a wheel space cavity to the main compressed fluid in a compressor discharge cavity. In such embodiments, the compressor discharge cavity is located inside the first flow path and proximate to the combustor and the wheel space cavity is located inside the second flow path and proximate to a rotor of the turbine. In certain embodiments, the method 300 further includes regulating a flow of the bypass compressed fluid using a labyrinth seal disposed in the second flow path upstream of the wheel space cavity. In one embodiment, at least one of the plurality of heat dissipating elements includes a heat pipe. In some embodiments, at least one of the plurality of heat dissipating elements comprises a vapor chamber. In some other embodiments, the plurality of heat dissipating elements comprises a heat pipe or a vapor chamber or combinations thereof.
[0039] In accordance with one or more embodiments discussed herein, the plurality of heat dissipating elements is configured to regulate temperature of bypass compressed fluid in a wheel space cavity, thereby allowing to reduce an amount of the bypass compressed fluid been circulated from a compressor to a turbine. Further, effective regulation of the temperature in the wheel space cavity allows the compressor to optimize compression ratio of the fluid. The plurality of heat dissipating elements may indirectly improve a shelf life of angel wings, rotor, and rub-strips of an intra-stage seal. The usage of the plurality of heat dissipating elements may reduce a need to use a high temperature alloy material in the wheel space, thereby significantly reducing cost and also design change required to the rotor of the turbine.
[0040] While only certain features of embodiments have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended embodiments are intended to cover all such modifications and changes as falling within the spirit of the invention.