WO2008059620A1

WO2008059620A1 - Film cooling structure

Info

Publication number: WO2008059620A1
Application number: PCT/JP2007/054910
Authority: WO
Inventors: Yoji Ohkita
Original assignee: Ihi Corporation
Priority date: 2006-11-13
Filing date: 2007-03-13
Publication date: 2008-05-22
Also published as: JP4941891B2; EP2083147A1; CA2668750C; EP2083147B1; CA2668750A1; US20100040459A1; EP2083147A4; JP2008121561A

Abstract

Film cooling structure (10) including structure wall (11) having outer surface (12) exposed to combustion gas and inner surface (13) positioned opposite to the outer surface (12), the film cooling structure (10) provided with film cooling hole (14) for, in the structure wall (11), leading of cooling air on the side of inner surface (13) to the side of outer surface (12) to thereby carry out film cooling of the outer surface (12), wherein the film cooling hole (14) has introduction portion (14a) extending from the inner surface (13) toward the outer surface (12) up to a mid position within the structure wall (11); enlarging portion (14b) having its cross section area gradually increasing from the end of the introduction portion (14a) on the side of outer surface (12) toward the outer surface (12) and opening on the outer surface (12); and partition portion (16) for partitioning of the interior of the enlarging portion (14b) into multiple units in the direction of hole width orthogonal to the direction of flow of combustion gas.

Description

Specification

Film cooling structure

Background of the Invention

[0001] Technical Field of the Invention

The present invention relates to a film cooling structure suitable for film cooling a surface of a component (turbine blade or the like) of a gas turbine engine.

[0002] Explanation of related technology

The efficiency of a gas turbine engine increases with increasing combustion gas temperature. This combustion gas heats the structural walls of components (combustor liners, turbine blades, turbine shrouds, etc.) placed in the combustion gas flow path. Heat to. Therefore, in order to efficiently cool the structural walls of such components, a cooling passage is provided in the interior, and cooling air is flowed to perform convection cooling, and cooling air is exposed to high-temperature combustion gas from the film cooling holes. A film cooling structure is employed in which film cooling is performed by ejecting a film on the surface (see, for example, Patent Documents:! To 5 below).

FIG. 1A to FIG. 1C show an example of a conventional film cooling structure 30. Figure 1B is 1B of Figure 1A

1B is a sectional view taken along line B, and FIG. 1C is a sectional view taken along line 1C-1C in FIG. 1B.

1B and 1C, the structural wall 31 has a surface 32 that is exposed to the combustion gas 1 and an inner surface 33 that is located on the opposite side of the surface 32. In the structural wall 31, film cooling holes 34 for guiding the cooling air 5 on the inner surface 33 side to the surface 32 side and cooling the film on the surface 32 are formed at a predetermined angle with respect to the surface 32. The film cooling hole 34 has an introduction portion 34a extending from the inner surface 33 toward the surface 32 to a middle position in the structural wall 31, and a cross-sectional area gradually increasing from the surface 32 side end portion of the introduction portion 34a toward the surface 32. It has an enlarged portion 34b (diffuser) that opens at the surface 32. As shown in FIG. 1B, in the enlarged portion 34b, the wall surface 35 facing the upstream side in the flow direction of the combustion gas 1 is formed linearly. Further, as shown in FIG. 1C, both side wall surfaces 36, 36 perpendicular to the flow direction of the combustion gas 1 are linearly formed in the enlarged portion 34b.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2006-9785

Patent Document 2: JP 2005-90511 A Patent Document 3: Japanese Patent Laid-Open No. 2003-41902

Patent Document 4: Japanese Patent Laid-Open No. 2001-173405

Patent Document 5: Japanese Patent Laid-Open No. 10-89005

In film cooling, it is desirable to spread the cooling air 5 as thin and wide as possible on the surface 32 to be cooled, and to adhere to the surface 32 as much as possible. Therefore, in order to spread the cooling air 5 thinly and widely on the surface 32, it is effective to increase the enlargement angle at the enlarged portion 34b as much as possible.

However, since the hole cross-sectional area increases linearly in the enlarged portion 34b of the conventional film cooling structure 30 described above, if the enlargement angle in the enlarged portion 34b is too large, the cooling air 5 is peeled inside the hole, For this reason, there is a problem that the cooling air 5 cannot be effectively diffused and it is difficult to improve the average film cooling efficiency.

Summary of invention

[0006] The present invention has been made in view of such problems, and provides a film cooling structure that can increase the expansion angle at the expansion portion and can improve the average film cooling efficiency. For the purpose.

[0007] In order to solve the above problems, the film cooling structure of the present invention employs the following means.

The present invention comprises a structural wall having a surface exposed to combustion gas and an inner surface located on the opposite side of the surface, and the cooling air on the inner surface side is guided to the structural wall to the surface side for film cooling of the surface. In the film cooling structure in which film cooling holes are formed, the film cooling holes include an introduction part extending from the inner surface toward the surface to a middle position in the structure wall, and a surface side of the introduction part. An enlarged portion whose cross-sectional area gradually increases from the end toward the surface and opens at the surface, and a partition portion that divides the inside of the enlarged portion in a hole width direction perpendicular to the flow direction of the combustion gas. It is characterized by having.

[0008] Thus, since the film cooling hole has the partition portion configured as described above, the effective area enlargement rate can be suppressed. Therefore, even if the lateral enlargement angle of the enlargement portion is increased, the cooling air can be reduced. Qi peeling is suppressed. Therefore, the cooling air can be effectively diffused compared to the conventional technology, and the enlargement angle in the lateral direction of the enlargement portion can be increased. Cooling air can be spread thinly and widely on the surface of the structural wall to improve average film cooling efficiency. The definition of the average film cooling efficiency will be described later.

In addition, since the cooling air can be spread more thinly and widely on the surface of the structural wall as compared with the prior art, the number of film cooling holes formed in the structural wall can be reduced. For this reason, the manufacturing process of the film cooling structure can be reduced. Further, since the amount of cooling air extracted from the compressor of the gas turbine engine can be reduced as the number of film cooling holes is reduced, the engine efficiency can be improved.

[0009] In the above film cooling structure, the partition portion is formed at an intermediate position in the hole width direction perpendicular to the flow direction of the combustion gas inside the film cooling hole, and the flow direction of the combustion gas One of the wall surface facing the upstream side and the wall surface facing the downstream side. The force protrudes toward the other side and extends from the inner surface of the structural wall toward the surface over the entire area inside the hole.

As described above, the partition portion does not completely partition the film cooling hole in the lateral direction and extends over the entire region in the thickness direction of the structural wall, so that the film cooling hole can be easily processed.

As described above, according to the present invention, it is possible to obtain an excellent effect that the enlargement angle at the enlargement portion can be increased and the average film cooling efficiency can be improved.

Brief Description of Drawings

FIG. 1A is a plan view showing a conventional film cooling structure.

1B is a cross-sectional view taken along line 1B-1B in FIG. 1A.

1C is a cross-sectional view taken along line 1C-1C in FIG. 1B.

FIG. 2 is a perspective view of a turbine rotor blade to which the film cooling structure of the present invention is applied.

FIG. 3A is a plan view showing a film cooling structure that applies force to an embodiment of the present invention.

3B is a cross-sectional view taken along line 3B-3B in FIG. 3A.

FIG. 3C is a cross-sectional view taken along line 3C-3C in FIG. 3B.

FIG. 4 is a perspective view showing the shape of a film cooling hole in a film cooling structure that works according to an embodiment of the present invention.

FIG. 5 is a diagram for explaining the physical action of the partition part.

DESCRIPTION OF PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

[0014] The film cooling structure of the present invention is applied to components arranged in a combustion gas flow path in a gas turbine engine. These components include a combustor liner, a turbine nose vane, a turbine nose nore band, a turbine blade, a turbine stationary blade, a turbine shroud, and a turbine exhaust liner.

FIG. 2 shows a perspective view of a turbine rotor blade 2 to which the film cooling structure 10 of the present invention is applied.

The turbine rotor blade 2 includes a blade portion 3 as a structural wall having a surface 12 exposed to the combustion gas 1 and a base portion 4 for mounting the blade portion 3 on an engine rotor. A cooling circuit (not shown) for flowing cooling air is formed inside the wing part 3. This cooling air is extracted from the compressor of the gas turbine engine and flows into the cooling circuit via a flow path (not shown) formed in the base portion 4. Cooling air that has flowed into the cooling circuit is ejected from a large number of film cooling holes 14 provided on the surface 12 of the wing 3 to cool the surface 12 of the wing 3. Hereinafter, an embodiment of the film cooling structure 10 of the present invention will be described.

[0016] FIGS. 3A-3C illustrate a film cooling structure 10 that works with embodiments of the present invention. FIG. 3A is a plan view showing the film cooling structure 10. 3B is a cross-sectional view taken along line 3B-3B of FIG. 3A. 3C is a cross-sectional view taken along line 3C-3C of FIG. 3B. FIG. 4 is a perspective view showing the shape of the film cooling hole 14 in the film cooling structure 10 according to the embodiment of the present invention.

[0017] As described above, the film cooling structure 10 is applied to components such as turbine rotor blades arranged in the flow path of the combustion gas 1 in a gas turbine engine. As shown in FIGS. 3B and 3C, the film cooling structure 10 includes a structural wall 11 having a surface 12 exposed to the combustion gas 1 and an inner surface 13 located on the opposite side of the surface 12. When the above-described component in the gas turbine is, for example, a turbine rotor blade, the wall constituting the blade portion of the turbine rotor blade is the structural wall 11. Cooling air 5 flows on the inner surface 13 side of the structural wall 11.

In the structural wall 11, film cooling holes 14 for guiding the cooling air 5 on the inner surface 13 side to the surface 12 side and cooling the film on the surface 12 are formed. As shown in FIG. 3B, the axis of the film cooling hole 14 is inclined at a predetermined angle with respect to the surface 12 of the structural wall 11 so that the cooling air 5 is blown out in the direction along the flow of the combustion gas 1. is doing. [0019] The film cooling hole 14 has an introduction portion 14a extending from the inner surface 13 toward the surface 12 to an intermediate position in the structural wall 11, and a cross-sectional area from the end of the introduction portion 14a on the surface 12 side toward the surface 12. Has an enlarged portion 14b that gradually increases and opens at the surface 12.

[0020] The film cooling hole 14 further includes a partitioning portion 16 that partitions the inside of the enlarged portion 14b into a plurality of holes in a hole width direction orthogonal to the flow direction of the combustion gas 1. Here, the “hole width direction perpendicular to the flow direction of the combustion gas 1” is a direction perpendicular to the paper surface in FIG. 3B, and a horizontal direction in FIG. 3C.

In the configuration examples shown in FIGS. 3A to 3C and FIG. 4, the partition 16 is formed at an intermediate position in the hole width direction perpendicular to the flow direction of the combustion gas 1 inside the film cooling hole 14. Projecting from the wall surface facing the upstream side in the flow direction toward the upstream side in the flow direction of the combustion gas 1 and extending from the inner surface 13 to the surface 12 of the structural wall 11 over the entire interior of the hole. A gap is formed between the partition portion 16 and the wall surface facing the downstream side in the flow direction of the combustion gas 1.

[0021] In the configuration example of Figs. 3A to 3C and Fig. 4, a single partitioning portion 16 may be provided at intervals in the hole width direction.

Further, in the configuration examples of FIGS. 3A to 3C and FIG. 4, the partition 16 is provided so as to protrude from the wall surface facing the upstream side in the flow direction of the combustion gas 1 toward the upstream side in the flow direction of the combustion gas 1. On the contrary, it may be provided so as to protrude from the wall surface facing the downstream side in the flow direction of the combustion gas 1 toward the downstream side in the flow direction of the combustion gas 1. In this case, a gap is formed between the partition portion 16 and the wall surface facing the upstream side in the flow direction of the combustion gas 1.

[0022] According to the present embodiment, the following operational effects are obtained.

Fig. 5 shows a graph of the diffuser with the length ratio on the logarithmic scale on the horizontal axis, the inlet / outlet area ratio minus 1 on the logarithmic scale on the vertical axis, and the pressure recovery rate (deceleration rate) Cp as a parameter. Show. At this time, in the case of the same inlet / outlet area ratio, the larger the length ratio, the smaller the enlargement angle. Further, peeling is less likely to occur when the pressure recovery rate is higher. The straight line indicated by the pressure recovery rate Cp * * in the figure is a line connecting the points where the maximum pressure recovery rate is obtained when the diffuser inlet / outlet area ratio is constant. On the other hand, the Cp * straight line is the line that provides the maximum pressure recovery rate when the length ratio is constant. Therefore, if the inlet / outlet area ratio is constant, It can be seen that the smaller the angle of enlargement, the higher the pressure recovery rate and the less likely the peeling occurs. Dividing the diffuser's passage into two or three equal parts, the expansion angle of each small passage becomes 1/2 or 1/3 of the overall expansion angle, and is smaller than the expansion angle determined by Cp *. As a result, a high pressure recovery rate can be obtained.

[0023] Therefore, according to the present embodiment, since the film cooling hole 14 includes the cutting portion 16 configured as described above, the effective area enlargement ratio can be suppressed, and thus the enlargement of the enlargement portion 14b in the lateral direction. Even if the angle is increased, the separation of the cooling air 5 is suppressed. For this reason, since the cooling air 5 can be effectively diffused as compared with the prior art, the lateral expansion angle of the enlarged portion 14b can be increased. It can be spread thinly and widely to improve the average film cooling efficiency. Here, the average film cooling efficiency is given by (fuel gas temperature / structure wall surface temperature) / (combustion gas temperature / cooling air temperature).

In addition, since the cooling air 5 can be spread more thinly and widely on the surface 12 of the structural wall 11 as compared with the prior art, the number of film cooling holes 14 formed in the structural wall 11 can be reduced. For this reason, the manufacturing process of the film cooling structure 10 can be reduced. Further, as the number of film cooling holes 14 decreases, the amount of cooling air extracted from the compressor of the gas turbine engine can be reduced, so that the engine efficiency can be improved.

[0025] When the film cooling holes 14 are processed by a method such as a discharge casing, if the partition 16 completely partitions the film cooling holes 14 in the lateral direction, the discharge casing is divided for each of the divided holes. It is necessary to insert the electrode and clean the hole. Further, if the partition 16 has a shape that is interrupted at a position in the thickness direction of the structural wall 11, a plurality of steps are required to cover one film cooling hole 14 (for example, the surface 12 side and the inner surface It is necessary to insert and process the discharge casing electrode from the 13th side). Further, the processing steps are similarly complicated in other processing means.

On the other hand, in the present embodiment, the partition 16 does not completely partition the film cooling hole 14 in the lateral direction, and extends over the entire region in the thickness direction of the structural wall 11, so that it is shown in FIGS. 3A to 3C and FIG. By inserting a discharge carriage electrode configured to cover the film cooling hole 14 from the surface 12 side, the film cooling hole 14 can be covered in a single step. Therefore, the film cooling hole 14 can be easily processed. Although the embodiments of the present invention have been described above, the embodiments of the present invention disclosed above are only examples, and the scope of the present invention is limited to these embodiments. Not. For example, in the above embodiment, the present invention is applied to the turbine rotor blade 2, but the combustor liner, the turbine nozle vane, the turbine nozle band, the turbine stationary blade arranged in the flow path of the combustion gas in the gas turbine engine. Also applicable to turbine shrouds, turbine exhaust liners and other components.

The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

Claims

The scope of the claims

[1] comprising a structural wall having a surface exposed to combustion gas and an inner surface located on the opposite side of the surface

In the film cooling structure, film cooling holes for guiding the cooling air on the inner surface side to the surface side and cooling the film on the surface are formed in the structural wall.

The film cooling hole includes an introduction portion extending from the inner surface toward the surface to an intermediate position in the structural wall, and a cross-sectional area gradually increasing from the surface side end portion of the introduction portion toward the surface. A film cooling structure comprising: an enlarged portion that opens; and a partition portion that divides the inside of the enlarged portion into a plurality of holes in a hole width direction orthogonal to the flow direction of the combustion gas.

[2] The partition portion is formed at an intermediate position in the hole width direction orthogonal to the flow direction of the combustion gas inside the film cooling hole, and faces a wall surface facing the upstream side and the downstream side of the flow direction of the combustion gas. 2. The film cooling structure according to claim 1, wherein the film cooling structure projects from one of the wall surfaces toward the other and extends from the inner surface of the structural wall toward the surface over the entire region inside the hole.