Gas turbine
The gas turbine design with a shroud segment and stator blade configuration addresses thermal expansion issues by using projections, recesses, and elastic members to maintain efficiency and prevent component contact, thus stabilizing operation and blade integrity.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- KAWASAKI JUKOGYO KK
- Filing Date
- 2025-01-14
- Publication Date
- 2026-07-23
Smart Images
Figure JP2025000857_23072026_PF_FP_ABST
Abstract
Description
Gas turbine
[0001] This disclosure relates to a gas turbine.
[0002] For example, in industrial gas turbines, in order to improve power generation efficiency, it is required to increase the temperature at the turbine inlet. In particular, the ambient temperature of the first-stage moving blades of the turbine near the outlet of the combustor is extremely high and tends to exceed the melting point of its material. Therefore, cooling of the turbine blades is essential. In particular, the rotating turbine moving blades require high strength from the perspective of centrifugal force, and various cooling structures are used to reduce the material temperature of the gas turbine (for example, Patent Document 1).
[0003] Japanese Patent Application Laid-Open No. 2006-144789
[0004] FIG. 8 shows an example of the cooling structure of a turbine moving blade. In the example of FIG. 8, a shroud segment 102 covering the outer periphery of the turbine moving blade 100 and a cooling air passage 108 are formed outside a stator shroud 106 connected to the turbine stator blade 104. The cooling air CA flowing through the cooling air passage 108 is supplied to the turbine moving blade 100 from a gap 110 between the shroud segment 102 and the stator shroud 106. Specifically, a cavity 112, which is an annular space, is formed at the outer diameter portion between the turbine moving blade 100 and the turbine stator blade 104, and the cooling air CA is supplied to the turbine moving blade 100 through this cavity 112.
[0005] On the other hand, in recent years' gas turbines for power generation, the demand for rapid start-up has been increasing. When the gas turbine is started rapidly, due to the transient thermal balance, a difference in thermal expansion occurs between the material components. This difference in thermal expansion may cause contact between the components. In the example of FIG. 8, there is a risk of clogging or contact in the gap 110 between the shroud segment 102 and the stator shroud 106.
[0006] Therefore, it is necessary to make the gap 110 between the shroud segment 102 and the stator vane shroud 106, that is, the axial distance between the two members 102 and 106, large. When this is done, the space formed as the cavity 112 becomes wider during rated operation when statically settled, so that swirling flow is more likely to occur due to stirring by the main flow medium (MF). As a result, a circumferential swirling flow similar to that of the main flow medium is formed inside the cavity 112. Due to the swirling flow generated inside the cavity 112, a striped pattern of high-pressure and low-pressure areas is formed inside the cavity 112 as shown in Figure 9. In Figure 9, the cross-hatched areas indicate high-pressure regions, and the hatched areas indicate low-pressure regions.
[0007] As shown in Figure 9, when a striped pattern is formed in the cavity 112 due to a pressure difference, this pressure pattern of the striped pattern propagates to the region of the turbine blade 100 in Figure 8. In this way, when the turbine blade 100 is subjected to fluctuating hydrodynamic forces, there is a risk that it may be subjected to adverse effects such as blade vibration.
[0008] The disclosures of this application provide a gas turbine that can achieve high turbine efficiency and suppress the generation of unstable pressure pulsations during static decomposition while preventing contact between components during rapid startup.
[0009] A gas turbine according to one embodiment of the present disclosure is a gas turbine comprising a rotor blade, a stator blade, and a gas-driven turbine, comprising: a shroud segment covering the outer circumference of the rotor blade; a stator blade shroud connected to the stator blade and covering the outer circumference of the stator blade; a cavity formed as an annular space on the outer diameter surface side of the stator blade shroud and the shroud segment, radially outward in the region between the stator blade and the rotor blade; a projection provided on one member of the stator blade shroud and the shroud segment and extending axially toward the other member; a recess provided on the other member of the stator blade shroud and the shroud segment; and at least one of an air hole formed in the projection and an air passage formed between the projection and the recess.
[0010] According to the gas turbine of this disclosure, the smooth flow of gas near the shroud suppresses the generation of unstable pressure pulsations that adversely affect the rotor blades, while ensuring high turbine performance. Furthermore, it prevents contact between components during rapid startup.
[0011] Any combination of at least two configurations disclosed in the claims and / or the specification and / or drawings is included in this disclosure. In particular, any combination of two or more of each claim in the claims is included in this disclosure.
[0012] This disclosure will be better understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustrative and explanatory purposes only and should not be used to define the scope of this disclosure. The scope of this disclosure is defined by the accompanying claims. In the accompanying drawings, the same part number in multiple drawings indicates the same part. This is a schematic cross-sectional view showing a gas turbine with a cooling structure according to the first embodiment of this disclosure. This is a schematic cross-sectional view showing an enlarged view of part II of Figure 1. This is a schematic cross-sectional view showing an enlarged view of part III of Figure 2. This is a schematic cross-sectional view showing a modified version of Figure 3. This is a schematic cross-sectional view showing another modified version of Figure 3. This is a schematic cross-sectional view showing yet another modified version of Figure 3. This is a schematic cross-sectional view showing yet another modified version of Figure 3. This is a schematic cross-sectional view showing a cooling structure for turbine blades of a conventional gas turbine. This is a cross-sectional view showing the fluid pressure distribution in the cavity of the gas turbine.
[0013] Preferred embodiments of the present disclosure will be described below with reference to the drawings. Figure 1 shows a schematic configuration of a gas turbine GT equipped with a cooling structure according to the first embodiment of the present disclosure. The gas turbine of this embodiment is an axial flow gas turbine used for power generation. As shown in Figure 1, the gas turbine GT comprises a compressor 1, a combustor 2, and a turbine 3 as its main components.
[0014] Compressed air A supplied from compressor 1 and fuel F supplied from a fuel supply device (not shown) are burned in combustor 2. The high-temperature, high-pressure gas G generated by the combustion is supplied to turbine 3, which drives turbine 3. Exhaust gas E is discharged from turbine 3. Compressor 1 is driven by turbine 3 via rotating shaft 4. Furthermore, turbine 3 drives a generator or other load element 6.
[0015] In the following explanation, unless otherwise specified, "axial direction," "radial direction," and "circumferential direction" refer to the axial, radial, and circumferential directions of the rotating shaft 4 of the gas turbine GT, respectively. Also, "upstream side" and "downstream side" refer to the upstream and downstream sides of the main flow in the axial direction. The main flow refers to the main gas flow of the gas turbine GT, i.e., the flow of compressed air A, gas G, etc. In Figures 1 to 8, the left side is the upstream side and the right side is the downstream side.
[0016] The compressor 1 in this embodiment is an axial-flow type compressor. The compressor 1 has a compressor rotor 8A provided upstream of the rotating shaft 4 of the gas turbine GT and a compressor stator 8B provided in the compressor casing 9. A compression passage 10 for compressing the intake air A1 is formed between the rotor 8A and the stator 8B.
[0017] The turbine 3 is located downstream of the rotating shaft 4 of the gas turbine GT and has a plurality of rotor blades 12 on its outer circumferential surface. A plurality of stator blades 14 are arranged in the turbine casing 11 that covers the radially outer side of the rotor blades 12. The rotor blades 12 and stator blades 14 are arranged alternately in the axial direction. Gas extracted from the compression passage 10 of the compressor 1 is supplied to the turbine blades 12 and 14 as cooling air CA.
[0018] Figure 2 shows an enlarged view of part II of Figure 1. Figure 2 shows the rotor blades 12 and stator blades 14 of the first stage of the turbine near the outlet of the combustor 2 (Figure 1). This disclosure can also be applied to rotor blades 12 and stator blades 14 other than those of the first stage of the turbine.
[0019] The gas turbine GT of this disclosure has a shroud segment 16 that covers the outer circumference of the rotor blade 12 and a stator blade shroud 18 that covers the outer circumference of the stator blade 14. The stator blade shroud 18 is connected to the stator blade 14. The shroud segment 16 and the stator blade shroud 18 are arranged side by side in the axial direction, and a gap 20 is provided between the shroud segment 16 and the stator blade shroud 18.
[0020] A cavity 22, consisting of an annular space, is formed radially outside the region R1 between the stationary vane 14 and the rotor blade 12, on the outer diameter surface side of the stationary vane shroud 18 and the shroud segment 16. The cavity 22 communicates with the region R1 between the stationary vane 14 and the rotor blade 12 via a gap 20.
[0021] The cavity 22 is formed by a plurality of wall portions. Specifically, it has a first wall portion 24 extending radially outward from the stator vane shroud 18, a second wall portion 26 extending radially outward from the shroud segment 16, and a third wall portion 28 extending axially downstream from the radially outer end of the first wall portion 24. These first to third wall portions 24, 26, and 28 form the cavity 22.
[0022] The first wall portion 24 and the second wall portion 26 each have through holes 24a and 26a extending in the axial direction. Multiple through holes 24a and 26a are provided spaced apart in the circumferential direction. Gas extracted from the compression passage 10 (Figure 1) of the compressor 1 is introduced into the cavity 22 through these through holes 24a and 26a and supplied to the turbine blades 12 and 14 as cooling air CA through the gap 20.
[0023] The second wall portion 26 has a smaller radial dimension than the first wall portion 24. The fourth wall portion 32, which extends downstream in the axial direction, is connected to the radially outer end of the second wall portion 26. After extending downstream in the axial direction, the fourth wall portion 32 is folded back and extends radially outward. In other words, the folded-back portion 34, which extends radially outward from the fourth wall portion 32, is connected to the axially downstream end of the fourth wall portion 32.
[0024] In this embodiment, the radially outer end face 34a of the folded portion 34 is located slightly radially outward from the outer diameter surface 28a of the third wall portion 28. That is, the surface 34b of the folded portion 34 facing axially upstream and the axially downstream end face 28b of the third wall portion 28 are axially opposite each other. An elastic member 30 is interposed between the surface 34b of the folded portion 34 facing axially upstream and the axially downstream end face 28b of the third wall portion 28. In other words, in this embodiment, the elastic member 30 is positioned between the third wall portion 28 and the second wall portion 26. Here, "the elastic member 30 is positioned between the third wall portion 28 and the second wall portion 26" also includes cases where the elastic member 30 is positioned between the fourth wall portion 32 and the folded portion 34 connected to the second wall portion 26 and the third wall portion 28.
[0025] The elastic member 30 applies an axial elastic force to the third wall portion 28 and the folded portion 34 so as to absorb the difference in axial thermal expansion between the stator vane shroud 18 and the shroud segment 16. In other words, the axial elastic force of the elastic member 30 is applied to the first wall portion 24 and the second wall portion 26 via the third wall portion 28 and the folded portion 34. As a result, when a difference in axial thermal expansion occurs between the stator vane shroud 18 and the shroud segment 16, the difference in thermal expansion between the two parts 18 and 16 is absorbed. In this embodiment, a spring member is used as the elastic member 30, but the elastic member 30 is not limited to a spring member.
[0026] Furthermore, if the second wall portion 26 has a larger radial dimension than the first wall portion 24, a third wall portion 28 extending axially upstream may be connected to the radially outer end of the second wall portion 26, a fourth wall portion 32 extending axially upstream may be connected to the radially outer end of the first wall portion 24, and a folded portion 34 extending radially outward may be connected to the axially upstream end of the fourth wall portion 32, with an elastic member 30 positioned between the third wall portion 28 and the folded portion 34. In other words, in this case, the elastic member 30 is positioned between the third wall portion 28 and the first wall portion 24. Here, "the elastic member 30 is positioned between the third wall portion 28 and the first wall portion 24" also includes cases where the elastic member 30 is positioned between the fourth wall portion 32 and the folded portion 34 connected to the first wall portion 24 and the third wall portion 28.
[0027] The stator vane shroud 18 has a projection 36 that extends axially toward the shroud segment 16. In other words, in this embodiment, the projection 36 is provided on the stator vane shroud 18, which is the upstream component of the stator vane shroud 18 and the shroud segment 16. The projection 36 extends to the vicinity of the upstream end face of the shroud segment 16. In other words, the radially inner side of the gap 20 is covered by the projection 36.
[0028] The inner diameter surfaces of the stationary vane shroud 18, the projection 36, and the shroud segment 16 are flush. Here, "flush" means that the inner diameter radii are the same. However, "flush" also includes cases where the difference in inner diameter radii is within ±0.5%.
[0029] A recessed portion 38 is provided in the shroud segment 16. In this embodiment, the recessed portion 38 is provided in the shroud segment 16, which is the downstream component of the stator vane shroud 18 and the shroud segment 16. The recessed portion 38 is provided at the upstream end of the shroud segment 16 and is recessed radially outward and axially downstream.
[0030] As shown in Figure 3, the projection 36 has an outer diameter surface that slopes radially inward from the base to the tip, i.e., toward the downstream side. Similarly, the recess 38 has an inner diameter surface that slopes radially inward as it moves away from the gap 20, i.e., toward the downstream side. In other words, in this embodiment, the recess 38 is composed of a sloped surface that recedes radially outward and toward the downstream side in the axial direction.
[0031] In this embodiment, the outer diameter surface of the projection 36 and the inner diameter surface of the recess 38 are substantially parallel. An air passage 40 is formed between the outer diameter surface of the projection 36 and the inner diameter surface of the recess 38. The air passage 40 is a passage that connects the cavity 22 and region R1. Because the outer diameter surface of the projection 36 and the inner diameter surface of the recess 38 are parallel, even if the projection 36 expands axially due to thermal expansion, it does not come into contact with the shroud segment 16 because the recess 38 is formed.
[0032] Next, the flow of the cooling air CA will be explained. When the turbine 3 in Figure 1 starts up, the compressor 1 is also driven in conjunction with it, and the intake air A1 is compressed in the compression passage 10. The gas extracted from the compression passage 10 is supplied to the turbine 3 as cooling air CA.
[0033] Cooling air CA extracted from the compression passage 10 is introduced into the cavity 22 through the through-hole 24a of the first wall portion 24 and the through-hole 26a of the second wall portion 26 in Figure 2. The cooling air CA introduced into the cavity 22 is supplied to the rotor blade 12 through the gap 20 and the air communication passage 40.
[0034] According to the above configuration, the gap 20 between the shroud segment 16 and the stator vane shroud 18 is covered from the radially inward by the projection 36. That is, the region R1 through which the main flow MF flows and the cavity 22 are separated by the projection 36. As a result, even if the gap 20 between the shroud segment 16 and the stator vane shroud 18 is made large, it is possible to prevent the cooling air CA in the cavity 22 from being stirred by the main flow MF in region R1. The cooling air CA in the cavity 22 flows into region R1 through the air passage 40. In this way, the cooling air CA flows smoothly into region R1 without being stirred by the main flow MF, thereby preventing unstable pressure pulsations. In addition, since the inner diameter surfaces of the projection 36 and the shroud segment 16 are flush with the portion through which the main flow MF flows, the main flow MF flows smoothly, ensuring high turbine performance.
[0035] Furthermore, since the outer diameter surface of the projection 36 and the inner diameter surface of the recess 38 are parallel, even if the projection 36 expands axially due to thermal expansion, the recess 38 prevents the projection 36 from contacting the shroud segment 16. As a result, even if the projection 36 extends to the vicinity of the shroud segment 16 to cover the gap 20, the thermally expanded projection 36 will not contact the shroud segment 16. Consequently, contact between the shroud segment 16 and the stator vane shroud 18 during rapid startup can be avoided. Thus, in the above embodiment, contact between parts during rapid startup can be prevented while also suppressing the generation of unstable pressure pulsations that adversely affect the rotor blades.
[0036] In this embodiment, an elastic member 30 is placed on the third wall portion 28 that forms the cavity 22. The elastic member 30 applies an elastic force in the axial direction to allow for changes in the axial dimension of the cavity 22. This suppresses changes in the axial dimension of the cavity.
[0037] In this embodiment, the structure of the present disclosure is applied to the turbine blades 12 of the first stage, which are located near the outlet of the combustor 2 (Figure 1). The ambient temperature of the turbine blades 12 of the first stage tends to be extremely high, but the configuration of the present disclosure eliminates problems caused by thermal expansion. However, the present disclosure can also be applied to turbine blades 12 other than those of the first stage.
[0038] The gas turbine GT of this embodiment is used for power generation. While there is a growing demand for rapid startup in power generation gas turbines, rapid startup of a gas turbine can lead to differences in thermal expansion between material components due to transient thermal balance. The configuration of this disclosure absorbs thermal expansion and avoids contact between components. However, this disclosure can also be applied to gas turbines other than those used for power generation.
[0039] The following describes modified versions of the protrusion 36 and recess 38 shown in Figure 3. Figure 4 shows modified versions of the protrusion 36 and recess 38. In the example in Figure 4, the protrusion 36 extends longer in the axial direction than in the example in Figure 3. Specifically, the protrusion 36 extends downstream beyond the upstream end face of the shroud segment 16, and in the cross-sectional view in Figure 4, a part of the protrusion 36 overlaps with the shroud segment 16 in the axial direction. Therefore, the gap 20 is covered from the radially inward by the protrusion 36, and the cooling air CA in the cavity 22 is prevented from being mixed with the main flow MF.
[0040] The outer diameter surface of the projection 36 is inclined radially inward toward the downstream side, and the inner diameter surface of the recess 38 is inclined radially outward toward the downstream side. In the example shown in Figure 4, the outer diameter surface of the projection 36 and the inner diameter surface of the recess 38 are parallel. In the region where the projection 36 and the shroud segment 16 overlap in the axial direction, the outer diameter surface of the tip 36a of the projection 36 and the inner diameter surface of the recess 38 face each other radially with a gap 42 in between. This prevents the projection 36 from coming into contact with the shroud segment 16 even if thermal expansion occurs in the axial direction of the projection 36.
[0041] Air holes 50 are formed in the projection 36. Multiple air holes 50 are provided spaced apart in the circumferential direction. Each air hole 50 penetrates the projection 36 radially. In the example of Figure 4, the air holes 50 extend in a direction that is inclined downstream toward the radially inward side. Cooling air CA in the cavity 22 is supplied to region R1 through the air holes 50. However, the air holes 50 do not have to be inclined with respect to the radial direction, and may extend radially.
[0042] In the example shown in Figure 4, the total passage area of the multiple air holes 50 arranged in the circumferential direction is set to be sufficiently larger than the passage area of the gap 42. Therefore, the cooling air CA in the cavity 22 is supplied to region R1 through the air holes 50 without passing through the gap 42. However, the passage area may be adjusted so that the cooling air CA passes through both the air holes 50 and the gap 42.
[0043] The modified form shown in Figure 4 produces the same effect as the structure in Figure 3. In other words, even with the modified form in Figure 4, it is possible to prevent contact between parts during rapid startup while suppressing the generation of unstable pressure pulsations that could adversely affect the rotor blades.
[0044] Figure 5 shows another modification of the protrusion 36 and recess 38. In the example of Figure 5, the protrusion 36 extends axially from the downstream member, the shroud segment 16, toward the upstream member, the stator vane shroud 18. In the example of Figure 5, the protrusion 36 extends to the edge of the stator vane shroud 18, i.e., near the downstream end face. Thus, the gap 20 is covered from the radially inward by the protrusion 36, preventing the cooling air CA in the cavity 22 from being mixed with the main flow MF.
[0045] The recessed portion 38 is provided in the stator shroud 18 which is an upstream member. The recessed portion 38 is a recessed portion that recesses radially outward from the inner diameter surface of the stator shroud 18. The amount of recess in the radial direction of the recessed portion 38 is set to be slightly larger than the thickness of the protruding portion 36 in the radial direction. That is, a gap 42 is formed between the inner diameter surface of the recessed portion 38 and the outer diameter surface of the protruding portion 36. Thereby, even if thermal expansion in the axial direction of the protruding portion 36 occurs, it is possible to avoid the protruding portion 36 from contacting the stator shroud 18. However, the radial dimension of the inner diameter surface of the recessed portion 38 and the radial dimension of the outer diameter surface of the protruding portion 36 may coincide, and the gap 42 may not be formed.
[0046] The tip of the protruding portion 36 may extend to the same position as the downstream end surface of the stator shroud 18 in the axial direction, or may be slightly forward, that is, located downstream. Also, the tip of the protruding portion 36 may extend upstream of the downstream end surface of the stator shroud 18. In this case, the protruding portion 36 and the stator shroud 18 partially overlap in the axial direction. Further, the protruding portion 36 may be provided on the stator shroud 18 which is an upstream member, and the recessed portion 38 may be provided on the shroud segment 16 which is a downstream member.
[0047] Air holes 50 are formed in the protruding portion 36. A plurality of air holes 50 are provided at intervals in the circumferential direction. Each air hole 50 penetrates the protruding portion 36 in the radial direction. In the example of FIG. 5, the air holes 50 extend in a direction inclined downstream toward the radially inner side. The cooling air CA in the cavity 22 is supplied to the region R1 through the air holes 50. However, the air holes 50 may not be inclined with respect to the radial direction and may extend in the radial direction.
[0048] In the example of FIG. 5, the passage area of the air holes 50 is set to be sufficiently larger than the passage area of the gap 42. Therefore, the cooling air CA in the cavity 22 is supplied to the region R1 through the air holes 50 without passing through the gap 42. However, the passage area may be adjusted so that the cooling air CA passes through both the air holes 50 and the gap 42.
[0049] The modified form in Figure 5 produces the same effect as the examples in Figures 3 and 4. In other words, even with the modified form in Figure 5, it is possible to prevent contact between parts during rapid startup while suppressing the generation of unstable pressure pulsations that could adversely affect the rotor blades.
[0050] Figure 6 shows yet another modification of the protruding portion 36 and the recessed portion 38. In the example of Figure 6, the protruding portion 36 is provided on the downstream member, the shroud segment 16, and the recessed portion 38 is provided on the upstream member, the stator vane shroud 18, which is the difference from the example of Figure 3, but the other structures are the same as in the example of Figure 3.
[0051] The projection 36 has an outer diameter surface that slopes radially inward from the base to the tip, i.e., toward the upstream side. Similarly, the recess 38 has an inner diameter surface that slopes radially inward as it moves away from the gap 20, i.e., toward the upstream side. In other words, in the example of Figure 6, the recess 38 is composed of a sloped surface that recedes radially outward and axially toward the upstream side. In this example as well, the gap 20 is covered from the radially inward side by the projection 36, and the cooling air CA in the cavity 22 is prevented from being mixed with the main flow medium (MF).
[0052] In the example shown in Figure 6, the outer diameter surface of the projection 36 and the inner diameter surface of the recess 38 are approximately parallel. An air passage 40 is formed between the outer diameter surface of the projection 36 and the inner diameter surface of the recess 38. The air passage 40 is a passage that connects the cavity 22 and region R1. Because the outer diameter surface of the projection 36 and the inner diameter surface of the recess 38 are parallel, even if the projection 36 expands axially due to thermal expansion, the expansion is absorbed by the recess 38 and does not come into contact with the stator vane shroud 18.
[0053] The modified form in Figure 6 produces the same effects as the examples in Figures 3 to 5. In other words, the modified form in Figure 6 also prevents contact between parts during rapid startup while suppressing the generation of unstable pressure pulsations that adversely affect the rotor blades. Furthermore, according to the modified form in Figure 6, the cooling air CA in the cavity 22 flows into region R1 along the air passage 40 in the opposite direction to the flow direction of the main flow MF. The cooling air CA that flows into region R1 is redirected by the main flow MF to reach the radially inner part of the rotor blade 12. As a result, not only the radially outer end of the rotor blade 12 but also the radially inner part can be cooled.
[0054] Figure 7 shows yet another modification of the protruding portion 36 and the recessed portion 38. In the example of Figure 7, the protruding portion 36 is provided on the downstream member, the shroud segment 16, and the recessed portion 38 is provided on the upstream member, the stator vane shroud 18, which is the difference from the example of Figure 4, but the other structures are the same as in the example of Figure 4.
[0055] The projection 36 has an outer diameter surface that slopes radially inward from the base to the tip, i.e., toward the upstream side. Similarly, the recess 38 has an inner diameter surface that slopes radially inward as it moves away from the gap 20, i.e., toward the upstream side. In other words, in the example of Figure 7, the recess 38 is composed of a sloped surface that recedes radially outward and axially toward the upstream side. In this example as well, the gap 20 is covered from the radially inward side by the projection 36, and the cooling air CA in the cavity 22 is prevented from being mixed with the main flow MF.
[0056] In the example shown in Figure 7, the outer diameter surface of the projection 36 and the inner diameter surface of the recess 38 are substantially parallel. Air holes 50 are formed in the projection 36. Multiple air holes 50 are provided spaced apart in the circumferential direction. Each air hole 50 penetrates the projection 36 radially. In the example shown in Figure 7, the air holes 50 extend in a direction that is inclined downstream toward the radially inward side. However, the air holes 50 do not have to be inclined with respect to the radial direction, and may extend radially. Cooling air CA in the cavity 22 is supplied to region R1 through the air holes 50. Because the outer diameter surface of the projection 36 and the inner diameter surface of the recess 38 are parallel, even if the projection 36 expands axially due to thermal expansion, the recess 38 prevents the projection 36 from contacting the stator vane shroud 18.
[0057] The modified form in Figure 7 produces the same effect as the examples in Figures 3 to 6. In other words, the modified form in Figure 6 also prevents contact between parts during rapid startup while suppressing the generation of unstable pressure pulsations that could adversely affect the rotor blades.
[0058] This disclosure is not limited to the forms described above, and various additions, modifications, or deletions are permitted as long as they do not deviate from the gist of this disclosure. Therefore, such additions, modifications, or deletions are also included within the scope of this disclosure.
Claims
1. A gas turbine comprising a rotor blade, a stator blade, and a gas-driven turbine, the gas turbine comprising: a shroud segment covering the outer circumference of the rotor blade; a stator blade shroud connected to the stator blade and covering the outer circumference of the stator blade; a cavity formed as an annular space on the radially outer side of the region between the stator blade and the rotor blade, on the outer diameter surface side of the stator blade shroud and the shroud segment; a projection provided on one member of the stator blade shroud and the shroud segment and extending axially toward the other member; a recess provided on the other member of the stator blade shroud and the shroud segment; and at least one of an air hole formed in the projection and an air passage formed between the projection and the recess.
2. A gas turbine according to claim 1, wherein the inner diameter surfaces of the stator blade shroud, the shroud segment, and the projection are flush.
3. A gas turbine according to claim 1 or 2, wherein the projection has an outer diameter surface that is inclined radially inward from the base to the tip, the recess has an inner diameter surface that is inclined radially inward as it moves away from the one member, and the air passage is formed between the recess and the projection.
4. A gas turbine according to claim 1 or 2, wherein the projection is provided on the downstream component of the stator vane shroud and the shroud segment in the direction of gas flow, and the recess is provided on the upstream component of the stator vane shroud and the shroud segment in the direction of gas flow.
5. A gas turbine according to claim 1 or 2, wherein the projection is provided on the upstream component of the stator vane shroud and the shroud segment in the direction of gas flow, and the recess is provided on the downstream component of the stator vane shroud and the shroud segment in the direction of gas flow.
6. A gas turbine according to claim 1 or 2, wherein the projection has an outer diameter surface that is inclined radially inward from the base to the tip, the recess has an inner diameter surface that is inclined radially inward as it moves away from the one member, the tip of the projection is radially opposite to the inner diameter surface of the recess, and a plurality of air holes are formed that penetrate the projection from the outer diameter side to the inner diameter side.
7. A gas turbine according to claim 1 or 2, wherein the projection extends to the edge of the other member, and the recess is a recess that is radially recessed from the inner diameter surface of the other member.
8. A gas turbine according to claim 1 or 2, further comprising an elastic member between the stator blade shroud and the shroud segment.
9. A gas turbine according to claim 8, further comprising: a first wall portion extending radially from the stator vane shroud; a second wall portion extending radially from the shroud segment; and a third wall portion extending axially from one of the first and second wall portions, wherein the cavity is formed by the first, second and third wall portions, and the elastic member is disposed between the third wall portion and the other wall portion of the first and second wall portions.