Combustor for gas turbine

Abstract

To successfully reduce speed of cooling air ejecting from a cooling hole to a combustion chamber without largely increasing weight of a combustor and effectively cool a liner of the combustor.SOLUTION: A liner 100 of a combustor 18 includes: a plurality of erected wall parts 114 extending in the circumferential direction, inclined to the axial direction and disposed at predetermined intervals in the axial direction; a plurality of cooling holes 120 formed to penetrate through the erected wall parts 114; and thick wall parts 122 each provided on an outer periphery of an end part of the cooling hole 120 of the erected wall part 114.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a combustor for a gas turbine. [Background technology]

[0002] A combustor for generating gas turbine combustion gas is generally disposed in a compressed air chamber and has a liner (housing) that defines a combustion chamber. To send cooling air along the inner surface of the wall of the liner, a liner having vertical wall portions and inclined wall portions alternately provided in the axial direction and having cooling holes formed through the vertical wall portions is known (for example, Patent Document 1).

[0003] In such a combustor, a portion of the compressed air flowing through the compressed air chamber is ejected as cooling air from the cooling holes into the combustion chamber so as to flow closely along the wall, thereby enabling the liner to be cooled appropriately. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US2013 / 0074507 A1 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to effectively cool the liner with the cooling air ejected from the cooling holes into the combustion chamber, it is preferable that the cooling air flows in a layer along the wall surface of the liner on the combustion chamber side.

[0006] If the flow velocity of the cooling air ejected from the cooling holes into the combustion chamber is high and the turbulent component is large, the cooling air tends to separate from the wall surface of the liner, hindering the cooling of the wall of the liner. Therefore, it is preferable to reduce the flow velocity of the cooling air as much as possible while the cooling air flows through the cooling holes. To achieve this, it is preferable to gradually increase the area of the cooling hole outlet relative to the cooling hole inlet, thereby promoting the deceleration of the cooling air flowing through the cooling holes. This allows the liner to be cooled effectively by the cooling air.

[0007] However, in order to effectively decelerate the cooling air in the cooling holes provided in the liner, it is necessary to increase the passage length of the cooling holes, which increases the wall thickness of the liner, i.e., the weight of the combustor, hindering weight reduction of the gas turbine engine.

[0008] In view of the above background, an object of the present invention is to suppress an increase in the weight of a combustor, to effectively decelerate the cooling air (cooling air flow) ejected from cooling holes into a combustion chamber, and to effectively cool the liner of the combustor. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, one aspect of the present invention is a gas turbine combustor (18) for generating combustion gas, which is arranged in a compressed air chamber (44) of a gas turbine engine (10), and which has a liner (100) that defines a combustion chamber (46) around a predetermined axis, and the liner has a plurality of upright wall portions (114) that extend in a circumferential direction, are inclined with respect to the direction of the axis, and are arranged at predetermined intervals in the direction of the axis, a plurality of cooling holes (120) formed through the upright wall portions, and thick portions (122) that are provided on the outer periphery of the upright wall portions at the ends of the cooling holes.

[0010] According to this aspect, the increase in the weight of the combustor is suppressed, the passage length of the cooling holes is increased, and the deceleration of the cooling air ejected from the cooling holes into the combustion chamber is effectively performed. In this case, the combustor may be an annular type or a can type.

[0011] In the above aspect, the thick portion may be provided on the inlet (120A) side and / or the outlet (120B) side of the cooling hole.

[0012] According to this aspect, the degree of freedom in designing the thick portion is increased.

[0013] In the above aspect, the thickened portion may be individually formed in an arch shape at the end of the cooling hole.

[0014] According to this aspect, an increase in the weight of the liner due to the thick portion is suppressed.

[0015] In the above aspect, the cooling hole may have a passage shape that includes a portion that widens from the compressed air chamber side toward the combustion chamber side.

[0016] According to this aspect, the cooling air ejected from the cooling holes into the combustion chamber is effectively decelerated, and the liner is effectively cooled.

[0017] In the above aspect, the cooling hole may have a cross-sectional shape that is enlarged in the circumferential direction on the combustion chamber side.

[0018] According to this aspect, the cooling air flowing along the wall surface of the combustion chamber is less likely to separate from the wall surface, and the liner is cooled effectively.

[0019] In the above aspect, the combustion chamber side of the cooling hole may have a trapezoidal cross section with the longer sides on the radially outer side.

[0020] According to this aspect, the cooling air flowing along the wall surface of the combustion chamber is less likely to separate from the wall surface, and the liner is cooled effectively.

[0021] In the above aspect, the cooling hole on the combustion chamber side may have a cross-sectional shape that forms a triangle with its base on the radially outer side.

[0022] According to this aspect, the cooling air flowing along the wall surface of the combustion chamber is less likely to separate from the wall surface, and the liner is cooled effectively.

[0023] In the above aspect, the liner may further have inclined wall portions (116) that are provided on the upstream and downstream sides of each upright wall portion so as to be continuous with the upright wall portions in the flow direction of the combustion gas, and that extend at an angle toward the inside of the combustion chamber along the flow direction of the combustion gas.

[0024] According to this aspect, the cooling air ejected from the cooling holes into the combustion chamber is more likely to flow along the wall surface on the combustion chamber side of the inclined wall portion that forms part of the wall of the liner. [Effects of the Invention]

[0025] According to the above aspect, an increase in the weight of the combustor is suppressed, the cooling air ejected from the cooling holes into the combustion chamber is decelerated well, and the liner of the combustor is effectively cooled. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a longitudinal cross-sectional view showing a power-generating gas turbine system to which a gas turbine combustor according to the present invention is applied. [Figure 2] FIG. 1 is a vertical cross-sectional perspective view showing a portion of a gas turbine combustor according to an embodiment of the present invention; [Figure 3] FIG. 1 is an explanatory diagram showing in detail a wall of a liner of a gas turbine combustor according to an embodiment of the present invention; [Figure 4] FIG. 1 is an enlarged perspective view of a longitudinal section showing a main portion of a gas turbine combustor according to an embodiment of the present invention. [Figure 5] FIG. 1 is an enlarged vertical cross-sectional view of a main portion of a gas turbine combustor according to an embodiment of the present invention. [Figure 6] 6 is a cross-sectional view taken along line VI-VI of FIG. [Figure 7] Arrow VII view of Figure 5 [Figure 8] 4 according to another embodiment. [Figure 9]FIG. 10 is an enlarged vertical cross-sectional view of a main portion of a gas turbine combustor according to another embodiment. [Figure 10] FIG. 10 is an enlarged perspective view of a longitudinal section showing a main portion of a gas turbine combustor according to another embodiment. [Figure 11] FIG. 10 is an explanatory diagram illustrating a wall shape of a gas turbine combustor according to another embodiment. [Figure 12] FIG. 10 is an explanatory diagram illustrating a wall shape of a gas turbine combustor according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0027] Fig. 1 is a cross-sectional view of a power-generating gas turbine system 10 to which a gas turbine combustor according to this embodiment is applied. As shown in Fig. 1, the power-generating gas turbine system 10 has a radial compressor 14 and a radial turbine 16 that are coaxially connected to each other by a rotating shaft 12. An input shaft of a generator 20 is connected to the rotating shaft 12.

[0028] The power generating gas turbine system 10 includes a front end plate 22 located on the side of the generator 20, a front housing 24, a middle housing 26, and a rear housing 28, arranged in this order in the axial direction.

[0029] The radial compressor 14 has a compressor liner 32 attached to the front housing 24 and defining a compressor chamber 30, a diffuser fixing member 36 that fixes a diffuser 34, and an air intake guide member 38 attached to the front end plate 22. The air intake guide member 38 cooperates with the compressor liner 32 to define an air intake port 40. A compressor rotor 42 attached to the rotary shaft 12 is rotatably disposed in the compressor chamber 30. The compressor rotor 42 is rotationally driven by the rotary shaft 12, which is the output shaft of the radial turbine 16.

[0030] The radial compressor 14 takes in air (outside air) from an air intake 40, compresses and pressurizes the air by the rotation of a compressor rotor 42, and ejects the compressed and pressurized air (compressed air) into the diffuser 34.

[0031] The rear housing 28 includes a portion that defines a compressed air chamber 44 into which compressed air is introduced from the diffuser 34. The compressed air chamber 44 has an annular cross-sectional shape about the central axis of the rotary shaft 12. The combustor 18 is provided in the compressed air chamber 44. The combustor 18 defines a combustion chamber 46 that has an annular cross-sectional shape about the central axis of the rotary shaft 12. A fuel injection nozzle 48 is attached to the combustor 18. The fuel injection nozzle 48 injects fuel into the combustion chamber 46.

[0032] The combustor 18 is provided within the rear housing 28 around the central axis of the rotary shaft 12. The rear housing 28 includes a portion that defines a compressed air chamber 44 that guides compressed air from the diffuser 34 to the combustor 18. The combustor 18 defines a combustion chamber 46. Fuel injection nozzles 48 are attached to various portions of the combustor 18. The fuel injection nozzles 48 inject fuel into the combustion chamber 46. In the combustion chamber 46, a mixture of fuel injected into the combustion chamber 46 by the fuel injection nozzles 48 and compressed air from the radial compressor 14 is combusted, generating high-temperature combustion gas (compressed fluid). A turbine nozzle 50 is provided at the gas outlet portion of the combustor 18.

[0033] The radial turbine 16 has a turbine chamber 52 that is defined by the inner portion of the rear housing 28 and communicates with the gas outlet portion of the combustor 18. The turbine chamber 52 is separated from the compressor chamber 30 by a partition member 54. The side of the turbine chamber 52 that is away from the partition member 54 is defined by a shroud 56. A radial turbine impeller 58 that is integrally formed with the rotary shaft 12 is rotatably disposed in the turbine chamber 52.

[0034] The turbine nozzle 50 is annular in shape so as to surround the radial turbine impeller 58, and injects combustion gas radially inward and circumferentially toward the radial turbine impeller 58. The radial turbine impeller 58 is rotationally driven by the combustion gas injected from the turbine nozzle 50. The combustion gas that has rotationally driven the radial turbine impeller 58 is discharged as exhaust gas into the atmosphere from an exhaust gas passage 60 defined by a tubular member connected to the rear end of the rear housing 28.

[0035] A rotor shaft 62 of the generator 20 is connected to the rotary shaft 12. As a result, the generator 20 is rotationally driven by the rotary shaft 12 of the radial turbine 16 to generate electricity.

[0036] The combustor 18 will be described in detail with reference to FIGS.

[0037] The combustor 18 is an annular combustor and, as shown in Fig. 1, has a liner (housing) 100 arranged approximately concentrically within the cylindrical compressed air chamber 44. As shown in Fig. 2, the liner 100 includes an annular end wall 102 extending in a direction approximately perpendicular to the axial direction, an outer peripheral wall 104 extending in the axial direction and having a substantially cylindrical shape, the outer peripheral wall 104 being connected to the outer peripheral edge of the end wall 102 at a first end 104A so as to be continuous with the outer peripheral edge of the end wall 102, and an inner peripheral wall 106 also extending in the axial direction and having a substantially cylindrical shape, the inner peripheral wall 106 being connected to the inner peripheral edge of the end wall 102 at a first end 106A so as to be continuous with the inner peripheral edge of the end wall 102, thereby defining the donut-shaped combustion chamber 46 around the central axis.

[0038] The liner 100 is manufactured by an additive manufacturing (AM) method in which metal is layered from bottom to top in an orientation in which the end wall 102 is on the bottom and the central axis of the liner 100 extends vertically.

[0039] The outer surface of the liner 100 is exposed to the flow of compressed air in the compressed air chamber 44 and is cooled using the compressed air as a cooling medium.

[0040] Mounting portions 110 for a plurality of fuel injection nozzles 48 are formed at predetermined intervals in the circumferential direction on the end wall 102. Each fuel injection nozzle 48 mixes air and fuel in the compressed air chamber 44 and injects the resulting mixture into the combustion chamber 46. In the combustion chamber 46, the mixture combusts, generating high-temperature combustion gases.

[0041] The outer peripheral wall 104 and the inner peripheral wall 106 have first ends 104A, 106A that are continuous with the end wall 102, and second ends 104B, 106B that are opposite in the axial direction to the first ends 104A, 106A. These second ends 104B, 106B cooperate with each other to define an annular combustion gas outlet 112 that opens radially inward. The combustion gas outlet 112 is connected to the turbine nozzle 50 (see FIG. 1) of the radial turbine 16 to supply fuel gas to the radial turbine 16.

[0042] The combustion gases flow through the combustion chamber 46 in a flow direction F indicated by the arrows in FIG. 2 from the end wall 102 toward the combustion gas outlet 112 .

[0043] Each of the outer peripheral wall 104 and the inner peripheral wall 106 has a plurality of upright wall portions 114 extending circumferentially and spaced apart at predetermined intervals in the axial direction, and an inclined wall portion 116 extending between adjacent upright wall portions 114 in the axial direction and continuing to the corresponding upright wall portion 114. More specifically, as shown in Fig. 3, each inclined wall portion 116 extends in an annular shape around the central axis between an outer edge portion 114A (side away from the combustion chamber 46) in the radial direction of the adjacent upright wall portion 114 on the upstream side with respect to the flow direction F of the combustion gas, and an inner edge portion 114B (side close to the combustion chamber 46) in the radial direction of the adjacent upright wall portion 114 on the downstream side.

[0044] In other words, when viewed in the flow direction F, each inclined wall portion 116 is connected at its leading edge to the inner edge 114B of the upright wall portion 114 on the downstream side, and at its trailing edge to the outer edge 114A of the upright wall portion 114 on the upstream side, and is inclined so that the side closest to the combustion chamber 46 is located downstream.

[0045] Each upright wall portion 114 is inclined radially in a direction in which the outer edge portion 114A is located downstream of the inner edge portion 114B in the flow direction F of the combustion gas in the combustion chamber 46. In this embodiment, each upright wall portion 114 forms a substantially right angle with the adjacent inclined wall portion 116 in a vertical cross section.

[0046] 2, a plurality of cooling holes 120 are formed through each of the upright wall portions 114 at predetermined intervals in the circumferential direction and so as to be approximately perpendicular to the upright wall portion 114 in a vertical cross-sectional view. In this embodiment, the plurality of cooling holes 120 are arranged in a row along the circumferential direction of the upright wall portion 114.

[0047] As shown in Figures 4 to 6, each cooling hole 120 has an inlet (compressed air chamber side end) 120A that opens toward the compressed air chamber 44 and an outlet (combustion chamber side end) 120B that opens toward the combustion chamber 46. Compressed air from the compressed air chamber 44 flows into each cooling hole 120 from the inlet 120A as cooling air. The compressed air that has flowed into each cooling hole 120 flows through the cooling hole 120 and is ejected from the outlet 120B toward the combustion chamber 46.

[0048] Each cooling hole 120 has a passage shape including an upstream portion 120C located on the inlet 120A side (compressed air chamber 44 side) that has a circular cross section and a substantially constant inner diameter along the longitudinal direction, and a downstream portion 120D located on the outlet 120B side (combustion chamber 46 side) that widens from the compressed air chamber 44 side toward the combustion chamber 46, thereby constituting a so-called shaped hole. Each cooling hole 120 is inclined with respect to the axial direction at an inclination angle substantially the same as the inclination with respect to the axial direction of the inner surface of the inclined wall portion 116 located downstream of the outlet 120B.

[0049] The downstream portion 120D (combustion chamber 46 side) of each cooling hole 120 gradually widens in the circumferential direction toward the outlet 120B, and has a trapezoidal cross-sectional shape (see Figure 6) with the longer side facing outside the combustion chamber 46.

[0050] Each upright wall portion 114 has an arch-shaped thickened portion 122 individually formed on the outer periphery of the inlet 120A of each cooling hole 120. Each thickened portion 122 extends the upstream portion 120C of the corresponding cooling hole 120 toward the inlet 120A by the thickness of the thickened portion 122, thereby increasing the passage length of the cooling hole 120.

[0051] The increased passage length of each cooling hole 120 sufficiently decelerates the compressed air (cooling air) injected from the outlet 120B into the combustion chamber 46. This reduces the tendency of the cooling air injected from each cooling hole 120 to separate from the inner surface of the outer peripheral wall 104 or the inner peripheral wall 106, and causes the cooling air to flow in layers along the inner surface of the outer peripheral wall 104 or the inner peripheral wall 106. This effectively cools the outer peripheral wall 104 and the inner peripheral wall 106.

[0052] The passage length of each cooling hole 120 is increased by the arch-shaped thickened portion 122 individually formed on the outer periphery of the inlet 120A, and therefore the passage length of each cooling hole 120 is extended without increasing the overall thickness of the outer circumferential wall 104 and the inner circumferential wall 106. This increases the passage length of each cooling hole 120 while suppressing an increase in the weight of the combustor 18. Furthermore, because the thickened portion 122 is arch-shaped and individually surrounds the outer periphery of the inlet 120A of each cooling hole 120, an increase in the weight of the combustor 18 due to the thickened portion 122 is suppressed.

[0053] One of the degradation patterns commonly observed in the liner 100 of the combustor 18 is cracks that initiate and propagate from the edge of the cooling holes 120. A structure such as the thickened portion 122, which extends only the inlet or outlet of each cooling hole 120, relieves stress at the edge of the cooling hole 120, thereby suppressing the occurrence of cracks originating from the hole edge, thereby improving the lifespan of the combustor 18. Furthermore, by increasing the passage length of the upstream portion 120C of the cooling hole 120, the length over which the inlet diameter remains constant increases. This suppresses changes in flow rate due to variations in the surface quality of the upstream portion 120C of the cooling hole 120 that occur during lamination when the liner 100 is manufactured by AM, stabilizing the flow rate. As a result, variations in the total flow rate of the numerous cooling holes 120 are also suppressed.

[0054] The downstream portion 120D of each cooling hole 120 is expanded from the compressed air chamber 44 side toward the combustion chamber 46, and the cross-sectional area gradually increases toward the combustion chamber 46, thereby reducing the flow rate of the cooling air flowing into the combustion chamber 46 and more effectively cooling the outer peripheral wall 104 and the inner peripheral wall 106.

[0055] Furthermore, because each cooling hole 120 is inclined with respect to the axial direction at an angle equivalent to the inclination of the inner surface of the inclined wall portion 116 with respect to the axial direction, the tendency of the cooling air to flow along the inner surfaces of the outer peripheral wall 104 and the inner peripheral wall 106 is promoted. Furthermore, because the downstream portion 120D of each cooling hole 120 has a trapezoidal cross section that is expanded in the circumferential direction and whose longer sides are on the radially outer side, the cooling air is encouraged to flow in layers along the inner surfaces of the outer peripheral wall 104 and the inner peripheral wall 106, thereby effectively cooling the outer peripheral wall 104 and the inner peripheral wall 106.

[0056] As described above, by effectively cooling the outer peripheral wall 104 and the inner peripheral wall 106, it is possible to increase the temperature of the combustion gas in the combustor 18, which in turn makes it possible to increase the pressure ratio of the compressor, thereby improving the efficiency of the gas turbine.

[0057] 8 shows the passage shape of the downstream portion 120D of each cooling hole 120 according to another embodiment. In this embodiment, the downstream portion 120D (on the combustion chamber 46 side) of each cooling hole 120 gradually expands in the circumferential direction toward the outlet 120B, and has a triangular cross-sectional shape with the longer side on the radially outer side.

[0058] In this embodiment as well, the cooling air flowing in layers along the inner surfaces of the outer peripheral wall 104 and the inner peripheral wall 106 is less likely to separate from the wall surfaces, thereby effectively cooling the outer peripheral wall 104 and the inner peripheral wall 106. In yet another embodiment, the downstream portion 120D (combustion chamber 46 side) of each cooling hole 120 may have an elliptical or oval shape that is long in the circumferential direction.

[0059] The thickened portion 122 provided in the upright wall portion 114 to extend the passage length of the cooling hole 120 may be provided not only at the inlet 120A of the cooling hole 120 but also at the outlet 120B side of the cooling hole 120, as shown in Figure 9.

[0060] By providing the thickened portions 122 on the inlet 120A side and the outlet 120B side of the cooling hole 120, the passage length of the cooling hole 120 is further increased, and the speed of the cooling air flowing through the cooling hole 120 is further improved. As a result, the cooling air flowing in layers along the inner surfaces of the outer peripheral wall 104 and the inner peripheral wall 106 is less likely to separate from the wall surfaces, and the outer peripheral wall 104 and the inner peripheral wall 106 are cooled more effectively.

[0061] The thick portion 122 may be provided only on the outlet 120B side of the cooling hole 120. These features increase the degree of freedom in designing the liner 100 of the combustor 18.

[0062] As shown in FIG. 10 , the thick-walled portion 122 may be formed in the shape of a shelf extending in the circumferential direction of the upright wall portion 114 across the plurality of cooling holes 120 arranged in a circumferential row, thereby extending the passage length of the plurality of cooling holes 120 collectively.

[0063] 11 , a cylindrical wall portion 124 is provided between the inner edge portion 114B of the upright wall portion 114 and the downstream edge of the inclined wall portion 116 on the upstream side of the upright wall portion 114, as viewed in the flow direction F of the combustion gas in the combustion chamber 46. The cylindrical wall portion 124 has a substantially constant diameter along the longitudinal direction. In this case, the upright wall portion 114 is a wall portion that rises radially outward from the cylindrical wall portion 124 toward the compressed air chamber 44.

[0064] 12 , as viewed in the flow direction F of combustion gas in the combustion chamber 46, a cylindrical wall portion 124 is provided between the outer edge portion 114A of the upright wall portion 114 and the upstream edge of the inclined wall portion 116 downstream of the upright wall portion 114. The cylindrical wall portion 124 has a substantially constant diameter along the longitudinal direction. In this case, the upright wall portion 114 is a wall portion that rises radially inward from the cylindrical wall portion 124 toward the combustion chamber 46.

[0065] Although the specific embodiment has been described above, the present invention is not limited to the above embodiment and can be widely modified and implemented.

[0066] For example, each upright wall portion 114 may be inclined at an angle other than a right angle relative to the adjacent inclined wall portion 116 in a vertical cross section. Also, the cooling holes 120 may penetrate the upright wall portion 114 while being inclined at an angle other than a right angle relative to the upright wall portion 114 in a vertical cross section.

[0067] The combustor 18 is not limited to an annular type, but may be a can type. Furthermore, the combustor 18 is not limited to a combustor for a gas turbine engine for power generation, but may be applied to combustors for various gas turbine engines, such as combustors for aircraft gas turbine engines. [Explanation of symbols]

[0068] 10: Gas turbine systems for power generation 16: Radial turbine 18: Combustor 44: Compressed air chamber 46: Combustion chamber 48: Fuel injection nozzle 100: Rina 102: End wall 104:Outer peripheral wall 106:Inner peripheral wall 110: Mounting part 112: Combustion gas outlet 114: Standing wall part 116: Inclined wall section 120: Cooling hole 120A: Entrance 120B: Exit 120C:Upstream part 120D: Downstream 122: Thick wall part F: Flow direction

Claims

1. 1. A combustor for a gas turbine, disposed in a compressed air chamber of a gas turbine engine, for generating combustion gases, comprising: a liner defining a combustion chamber about a predetermined axis; The liner comprises: a plurality of upright wall portions extending in a circumferential direction, inclined with respect to the axis direction, and arranged at predetermined intervals in the axis direction; a plurality of cooling holes formed through the upright wall portion; a thick portion provided on an outer periphery of the end of the cooling hole of the upright wall portion.

2. 2. The gas turbine combustor according to claim 1, wherein the thick-walled portion is provided on an inlet side and / or an outlet side of the cooling hole.

3. 3. The gas turbine combustor according to claim 1, wherein the thick-walled portions are individually formed in an arch shape at the ends of the cooling holes.

4. 3. The combustor for a gas turbine according to claim 1, wherein the cooling hole has a passage shape including a portion that widens from the compressed air chamber side toward the combustion chamber side.

5. 3. The combustor for a gas turbine according to claim 1, wherein the cooling hole on the combustion chamber side has a cross-sectional shape expanded in the circumferential direction.

6. 3. The combustor for a gas turbine according to claim 1, wherein the cooling hole on the combustion chamber side has a trapezoidal cross section whose longer sides are on the radially outer sides.

7. 3. The combustor for a gas turbine according to claim 1, wherein the cooling hole on the combustion chamber side has a cross section that forms a triangle with its base on a radially outer side.

8. 3. The combustor for a gas turbine according to claim 1, wherein the liner further comprises inclined wall portions provided on the upstream and downstream sides of the upright wall portions in relation to the flow direction of the combustion gas so as to be continuous with the upright wall portions and extending at an angle toward an interior of the combustion chamber along the flow direction of the combustion gas.

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