A turbine outer ring and its cooling air film hole layout method

Abstract

The present application provides a layout method for cooling air film holes on the outer ring of a turbine. The method includes: conducting three-dimensional fluid-structure-thermal coupling simulation calculations on the tip clearance area where the outer ring of the turbine is located, obtaining the wall temperature distribution on the gas side of the outer ring of the turbine, and dividing the wall of the gas side of the outer ring of the turbine into three temperature zones along the axial direction; determining the target comprehensive cooling efficiency of the cooling air film holes, obtaining the total cooling air consumption and the cooling air consumption of each cooling air film hole; arranging a row of leading-edge cooling air film holes circumferentially at the leading edge of the outer ring of the turbine to obtain a wall temperature cooling efficiency contour map with circumferential full coverage under the leading-edge cooling air film holes, setting a first row of cooling air film holes at positions that cannot be covered by the leading-edge cooling air film holes to obtain a wall temperature cooling efficiency contour map with circumferential full coverage under the first row of cooling air film holes, and setting a second row of cooling air film holes at positions that cannot be covered under the first row of cooling air film holes; repeating the above process until the cold air of multiple rows of cooling air film holes can completely cover the first two temperature zones.

Description

Technical Field

[0001] This application belongs to the technical field of aeroengines, and particularly relates to a turbine outer ring and a layout method for its cooling air film holes. Background Art

[0002] With the continuous increase in the turbine inlet temperature (i.e., the temperature in front of the turbine guide vane), the temperature-bearing capacity of the turbine outer ring, one of the high-temperature components of the engine, also needs to be continuously improved. The improvement of the temperature-bearing capacity of the turbine outer ring is generally achieved through two methods: one is the improvement of the cooling structure, and the other is the improvement of the performance of the metal material. Compared with the improvement of the performance of the metal material, the improvement of the cooling structure of the turbine outer ring can bring more benefits to the turbine outer ring, such as lower cost and shorter R & D cycle. Therefore, at present, for the turbine outer ring, a better method is to improve the cooling structure of the turbine outer ring to enhance the cooling effect of the turbine outer ring.

[0003] As Figure 1 shown in the schematic diagram of the typical cooling structure of the turbine outer ring in the prior art, the turbine outer ring 2 is arranged on the casing 3, and the rotor blades 1 are arranged inside the turbine outer ring 2. The external cooling gas Q2 impacts and cools the turbine outer ring 2 from the injection holes 31 of the casing 3, and converges in the collection cavity 22 between the casing 3 and the turbine outer ring 2, and then flows into the main flow channel from the air film cooling holes 21 on the turbine outer ring 2, mixes with the main combustion gas Q1 in the main flow channel, and the cold air flowing out from the air film cooling holes 21 forms a protective air film inside the turbine outer ring 2.

[0004] However, the current layout of the cooling air film holes usually selects the array air film hole structure with the known highest cooling effect at a certain blowing ratio - that is, for a group of array air film holes, a group of array structures with the highest cooling efficiency are obtained by changing their hole pitch, row pitch, and hole inclination angle, and then applied to the turbine outer ring.

[0005] However, the turbine outer ring 2 obtained by this method is restricted by various structures, and the air film cooling holes 21 at the edge cannot adopt the optimal layout method, so that the cooling effect at the edge of the turbine outer ring 2 cannot reach the expectation and the cooling effect is poor. In addition, the sweep of the blade 1 will make the heat transfer boundary on the hot side of the outer ring unstable and uneven, and the current design method will cause inefficient utilization of the cooling air.

[0006] Therefore, an effective layout method for the cooling air film holes of the turbine outer block is needed to improve the air film cooling effect of the turbine outer ring. Summary of the Invention

[0007] The purpose of this application is to provide a layout method for the cooling air film holes of the turbine outer ring to solve or alleviate at least one problem in the background art.

[0008] The technical solution of this application is: a layout method for cooling air film holes on the outer ring of a turbine, characterized in that the method includes:

[0009] Conduct three-dimensional fluid-structure-thermal coupling simulation calculations on the tip clearance area where the outer ring of the turbine is located, obtain the wall temperature distribution on the gas side of the outer ring of the turbine, and divide the wall on the gas side of the outer ring of the turbine into three temperature zones along the axial direction according to the wall temperature distribution on the gas side of the outer ring of the turbine;

[0010] Determine the target comprehensive cooling effectiveness of the cooling air film holes, and determine the blowing ratio to achieve the target comprehensive cooling effectiveness according to the target comprehensive cooling effectiveness, so as to obtain the total cooling air consumption and the cooling air consumption of each cooling air film hole;

[0011] Arrange a row of leading-edge cooling air film holes circumferentially at the leading edge of the outer ring of the turbine, and conduct three-dimensional numerical simulation analysis to obtain the wall temperature cooling effectiveness contour map with circumferential full coverage under the leading-edge cooling air film holes. Set the first row of cooling air film holes at the positions that cannot be covered by the leading-edge cooling air film holes in the wall temperature cooling effectiveness contour map under the leading-edge cooling air film holes, and conduct three-dimensional numerical simulation analysis to obtain the wall temperature cooling effectiveness contour map with circumferential full coverage under the first row of cooling air film holes. Set the second row of cooling air film holes at the positions that cannot be covered by the first row of cooling air film holes in the wall temperature cooling effectiveness contour map under the first row of cooling air film holes;

[0012] Repeat the above process until the cooling air of multiple rows of cooling air film holes can completely cover the first two temperature zones.

[0013] Furthermore, when conducting three-dimensional fluid-structure-thermal coupling simulation calculations on the tip clearance area where the outer ring of the turbine is located, the outer ring of the turbine adopts a turbine outer ring model without a cooling structure.

[0014] Furthermore, the target comprehensive cooling effectiveness of the cooling air film holes is:

[0015] In the formula, Tg is the inlet temperature of the high-pressure turbine;

[0016] Tc is the cooling air temperature;

[0017] Ts is the long-term allowable temperature of the material used for the outer ring of the turbine.

[0018] Furthermore, the circumferential full coverage of the cooling air film holes is achieved by adjusting the parameters of the cooling air film holes, and the parameters include hole diameter, spacing, and axial position.

[0019] Furthermore, the first temperature zone is the wall area of the outer ring of the turbine between the leading edge of the outer ring of the turbine and the leading edge of the tip, the second temperature zone is the wall area of the outer ring of the turbine corresponding to the leading edge of the tip to half of the tip, and the third temperature zone is the wall area of the outer ring of the turbine between half of the tip and the trailing edge of the outer ring of the turbine.

[0020] Further, at least one row of cooling air film holes is included in the first temperature zone, and at least one row of cooling air film holes is included in the second temperature zone.

[0021] Further, when arranging the cooling air film holes, the following principles are followed:

[0022] The air film ejected from the cooling air film holes can completely cover the outer wall surface of the turbine, the overlapping area of the air film coverage area and the non-overlapping area do not exceed 10%, and the area not covered by the cooling gas between the hole pitches of the cooling air film holes and between the hole rows does not exceed 5%.

[0023] In addition, the present application also provides a turbine outer ring, which includes one row or multiple rows of cooling air film holes, and the cooling air film holes are arranged according to any one of the above turbine outer ring cooling air film hole layout methods.

[0024] The turbine outer ring cooling air film hole layout method provided by the present application fully considers the aerodynamic performance and structural characteristics of the turbine outer ring, adopts the design concept of advancing in sequence and concentrating on cooling, ensures that the cold air flowing out of the cooling air film holes can achieve the wall attachment effect and the superposition effect, can realize the full-surface cooling of the high-temperature area of the gas side wall surface of the turbine outer ring, and ensures the cooling protection requirements. Brief Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions provided by the present application, the drawings will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application.

[0026] Figure 1 It is a schematic diagram of a typical turbine outer ring cooling structure in the prior art.

[0027] Figure 2 It is a flow chart of the turbine outer ring cooling air film hole layout method of the present application.

[0028] Figure 3 It is the circumferential average temperature ratio curve of the gas side wall surface of the turbine outer ring in the embodiment of the present application.

[0029] Figure 4 It is the circumferential average static pressure ratio curve of the gas side wall surface of the turbine outer ring in the embodiment of the present application.

[0030] Figure 5 It is the cold effect cloud map of the cooling air film holes at the leading edge of the hot side surface of the turbine outer ring in an embodiment of the present application.

[0031] Figure 6 It is the cold effect cloud map of the first row of cooling air film holes on the hot side surface of the turbine outer ring in an embodiment of the present application.

[0032] Figure 7 It is the schematic diagram of the arrangement of the cooling air film holes of the turbine outer ring in an embodiment of the present application. Detailed implementation manners

[0033] To make the objectives, technical solutions, and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings in the embodiments of this application.

[0034] In view of the performance and structural characteristics of the turbine outer ring, a layout method for cooling air film holes of the turbine outer ring is proposed in this application. This method can break through the constraints of the current array air film hole design by structural limitations, greatly improve the wall attachment effect and superposition effect of the air film, and achieve the purpose of efficient cooling of the cooling air.

[0035] As Figure 2 shown, the layout method for cooling air film holes of the turbine outer ring provided in this application includes the following process:

[0036] S1. Conduct an aerodynamic performance analysis of the tip clearance area where the turbine outer ring is located. Use a turbine outer ring model without a cooling structure and a computational model of the turbine stage performance channel to perform three-dimensional fluid-structure-thermal coupling simulation calculations to obtain the wall / surface temperature distribution and pressure distribution on the gas side of the turbine outer ring, as Figure 3 and Figure 4 shown. As can be seen from Figure 3 and Figure 4 , the gas-side surface of the turbine outer ring wall is in a tip clearance environment where the temperature distribution and pressure distribution do not match. The surface temperature distribution trend of the gas side of the turbine outer ring shows a distribution that is low at the front and back and high in the middle. The temperature is the highest in the tip sweep area (x≈[2L - 4L]) at the leading edge of the rotor blade, while the surface pressure distribution on the gas side of the turbine outer ring is high at the front and back and low in the middle, and there is a large pressure gradient along the axial direction in the clearance.

[0037] However, for the turbine outer ring, more cooling air flows to the rear end of the turbine outer ring, but the temperature at the rear end of the turbine outer ring is significantly lower than that at the front end of the turbine outer ring. Therefore, the demand for cooling air in the rear section is small, while the temperature in the front end of the turbine outer ring facing the high-temperature gas erosion and the tip sweep area is relatively high and requires more cooling air, but only less cooling air can be obtained.

[0038] Therefore, in this application, according to the temperature curve distribution characteristics of the gas-side surface of the turbine outer ring, the gas-side wall surface of the turbine outer ring is partitioned. The first temperature zone is the wall surface area of the turbine outer ring between the leading edge of the turbine outer ring and the leading edge of the tip, corresponding to the axial position x≈[1L - 2L] of the turbine outer ring wall surface in Figure 3 ; the second temperature zone is the wall surface area of the turbine outer ring corresponding to the area from the leading edge of the tip to half of the tip, corresponding to the axial position x≈[2L - 4L] of the turbine outer ring wall surface in Figure 3 , and this area is the area with the highest temperature on the gas-side wall surface of the turbine outer ring; the third temperature zone is the wall surface area of the turbine outer ring between half of the tip and the trailing edge of the turbine outer ring, corresponding toFigure 3 The axis position x of the outer wall of the middle turbine is approximately [4L - 6.5L], and the temperature starts to drop in this area, with a low temperature.

[0039] S2. Conduct a preliminary design of the cooling structure according to the cooling requirements of the gas side wall of the outer ring of the turbine

[0040] Determine the target comprehensive cooling efficiency of the cooling air film holes according to the inlet temperature Tg of the high-pressure turbine, the temperature Tc of the cooling air, and the long-term allowable temperature Ts of the material used for the outer ring of the turbine:

[0041] Then, according to the conclusion of the basic research, determine a reasonable blowing ratio M that can achieve the target comprehensive cooling efficiency. According to the blowing ratio and the total cooling air consumption m c The cooling air consumption m' of each air film hole can be calculated and used as the boundary input for subsequent numerical calculations or simulation analyses. c ', as the boundary input for subsequent numerical calculations or simulation analyses.

[0042] S3. Layout the air film holes according to three-dimensional numerical simulation

[0043] Arrange the leading-edge cooling air film holes at the leading edge of the outer ring of the turbine, and then conduct a three-dimensional numerical simulation analysis of the outer ring of the turbine and its corresponding structure to obtain the cloud map of the temperature cooling efficiency distribution of the gas side wall of the outer ring of the turbine under the leading-edge cooling air film holes. According to this wall temperature cooling efficiency distribution cloud map, adjust the parameters of the leading-edge cooling air film holes - including but not limited to the aperture, spacing, axial position, etc., so that the leading-edge wall of the outer ring of the turbine can achieve a circumferential full coverage of the cold air.

[0044] See Figure 5 The figure shows the cloud map of the wall temperature cooling efficiency achieved by the leading-edge cooling air film holes of a partial cross-section of the outer ring of the turbine in an embodiment of the present application. In this wall temperature cooling efficiency cloud map, the lighter the color, the lower the temperature, that is, the better the wall temperature reduction effect that the cooling air film holes can achieve.

[0045] After that, set the first row of cooling air film holes on the gas side wall according to the position where the leading-edge cooling air film gas cooling efficiency just cannot cover in the cloud map of the wall temperature cooling efficiency of the leading-edge air film holes. This first row of cooling air film holes is arranged in the first temperature zone.

[0046] As Figure 6 The figure shows the schematic diagram of the first row of cooling air film holes arranged in this embodiment of the present application. Since the leading-edge cooling air film holes can approximately cover up to the position of 1.5L, the first row of cooling air film holes is set at a position close to after 1.5L. At the same time, in combination with Figure 3 and Figure 6 shown, the first temperature zone is between 1L and 2L, and this first row of cooling air film holes is located within the first temperature zone of 1L - 2L.

[0047] In addition, from Figure 6It can be seen that the cooling effect of the first row of cooling air film holes can reach about 2.5L~3L, which has exceeded the range of the first temperature zone. Therefore, in this embodiment of the present application, only one row of cooling air film holes is set in the first temperature zone.

[0048] The second row of exhaust film holes is arranged in the same way, and the second row of cooling film holes is arranged exactly at the position where the cooling effect of the first row of cooling film holes just cannot cover. Figure 6 According to the cooling efficiency distribution diagram, the second row of cooling air film holes can be arranged at approximately 2.8L.

[0049] Repeat the above steps and arrange the cooling film holes in sequence until the cold air from the cooling film holes can completely cover the first temperature zone (1L~2L) and the second temperature zone (2L~4L), thus completing the layout of the cooling film holes on the turbine outer ring.

[0050] It should be noted that when laying out the cooling air film holes, the following principles should be followed: the air film covers the wall surface well, there is no excessive overlap or gaps in the cooling gas coverage area, and there should be no positions that are not covered by the cooling gas between the cooling air film holes and between the hole rows.

[0051] like Figure 7 Shown is a schematic diagram of the positions of the leading edge cooling film holes 21A, the first row of cooling film holes 21B, and the second row of cooling film holes 21C in the above embodiment of the present application, and the third row and subsequent cooling film holes are not shown.

[0052] Finally, the present application also provides a turbine outer ring having an air film cooling structure, namely, cooling air film holes arranged axially along the turbine outer ring, and the cooling air film holes are completed by the layout method of the above process.

[0053] The layout method of the cooling air film holes of the turbine outer ring provided in the present application fully considers the aerodynamic performance and structural characteristics of the turbine outer ring, and adopts the design concept of sequential advancement and concentrated cooling, which ensures that the cold air flowing out of the cooling air film holes can achieve the wall-sticking effect and the superposition effect, and can realize full-surface cooling of the high-temperature area of ​​the gas side wall of the turbine outer ring, ensuring the cooling protection requirements.

[0054] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A layout method for cooling air film holes in the outer ring of a turbine, characterized in that The method includes: Conducting three-dimensional fluid-structure-thermal coupling simulation calculations on the tip clearance area where the outer ring of the turbine is located to obtain the wall temperature distribution on the gas side of the outer ring of the turbine. According to the wall temperature distribution on the gas side of the outer ring of the turbine, the wall surface of the outer ring of the turbine on the gas side is axially divided into three temperature zones. Among them, the first temperature zone is the wall surface area of the outer ring of the turbine between the leading edge of the outer ring of the turbine and the leading edge of the tip; the second temperature zone is the wall surface area of the outer ring of the turbine corresponding to the position from the leading edge of the tip to half of the tip; the third temperature zone is the wall surface area of the outer ring of the turbine between half of the tip and the trailing edge of the outer ring of the turbine. Determine the target comprehensive cooling effectiveness of the cooling air film holes, and determine the blowing ratio to achieve the target comprehensive cooling effectiveness according to the target comprehensive cooling effectiveness, so as to obtain the total cooling air consumption and the cooling air consumption of each cooling air film hole. The target comprehensive cooling effectiveness of the cooling air film holes is as follows: Tg is the inlet temperature of the high-pressure turbine, Tc is the cooling air temperature, and Ts is the long-term allowable temperature of the material used for the outer ring of the turbine; Arranging a row of leading-edge cooling film holes circumferentially at the leading edge of the outer ring of the turbine, and conducting three-dimensional numerical simulation analysis to obtain the wall temperature cooling effect cloud map with circumferential full coverage under the leading-edge cooling film holes. According to the positions that cannot be covered by the leading-edge cooling film holes in the wall temperature cooling effect cloud map under the leading-edge cooling film holes, set the first row of cooling film holes, and conduct three-dimensional numerical simulation analysis to obtain the wall temperature cooling effect cloud map with circumferential full coverage under the first row of cooling film holes. According to the positions that cannot be covered by the first row of cooling film holes in the wall temperature cooling effect cloud map under the first row of cooling film holes, set the second row of cooling film holes. Repeat the above process until the cold air of multiple rows of cooling film holes can completely cover the first two temperature zones.

2. The method for arranging the cooling air film holes on the outer ring of the turbine according to claim 1, characterized in that, When conducting three-dimensional fluid-structure-thermal coupling simulation calculations on the tip clearance area where the outer ring of the turbine is located, the outer ring of the turbine uses a turbine outer ring model without a cooling structure.

3. The method for arranging the cooling air film holes of the turbine outer ring according to claim 1, wherein Achieve circumferential full coverage of the cooling film holes by adjusting the parameters of the cooling film holes. The parameters include aperture, pitch, and axial position.

4. The method for arranging the cooling air film holes of the turbine outer ring according to claim 1, characterized in that, At least one row of cooling film holes is included in the first temperature zone, and at least one row of cooling film holes is included in the second temperature zone.

5. The method for arranging the cooling air film holes on the outer ring of the turbine according to claim 4, characterized in that, When arranging the cooling film holes, follow the following principles: The gas film ejected from the cooling film holes can completely cover the wall surface of the outer ring of the turbine. The overlapping area and the non-covered area of the gas film coverage area do not exceed 10%. The non-covered area between the hole pitches of the cooling film holes and between the hole rows does not exceed 5%.

6. A turbine outer ring, characterized in that, The outer ring of the turbine includes one row or multiple rows of cooling film holes, and the cooling film holes are arranged according to the layout method of the cooling film holes of the outer ring of the turbine described in any one of claims 1 to 5.

Images