Gas film hole structure of engine cooling wall surface and gas film forming method

Abstract

The application relates to a gas film hole structure of an engine cooling wall surface, which comprises a cooling wall surface, a plurality of gas film holes arranged in a matrix on the cooling wall surface, and a method for forming a cooling gas film. The gas film holes are discontinuous annular holes composed of at least two sector ring holes and sector ring partitions for connecting two sector ring holes. The method for forming the cooling gas film is that secondary flow C1 flows on the upper surface of a gas film plate, then flows into or is sucked into the gas film holes, after heat exchange between airflow C2 and the wall surface of the gas film plate, outflow C3 of the gas film is formed, which is mixed with main flow C4 to reduce the temperature of the wall surface gas, and on the other hand, the cold gas forms a gas film on the wall surface to cover and block the scouring of the gas on the wall surface. The application has the advantages of simple structure, increased gas film covering area, improved gas film cooling effect, effectively reduced wall temperature and improved cold gas utilization rate.

Description

Technical Field

[0001] This invention relates to the structure and cooling method of cooling walls for gas turbine engines. Background Technology

[0002] Thermal issues in aero-engines are critical to their performance and lifespan. With continuous improvements in aero-engine performance, the latest generation of aero-engines has turbine inlet temperatures reaching 1800-2200K, far exceeding the temperature limits of turbine materials. Statistics show that over 40% of engine failures are caused by thermal erosion of aero-engine turbine blades. Therefore, turbine blade cooling is one of the key issues for improving aero-engine performance and extending its service life. The afterburner is a crucial component in military aircraft. When afterburner is engaged, it significantly increases the instantaneous thrust of the aero-engine, improving the aircraft's maneuverability. However, the mainstream combustion gas temperature in the afterburner also reaches 2200K, far exceeding the temperature limits of the afterburner casing materials. Therefore, the afterburner casing walls also require cooling. In summary, many walls in aero-engines require cooling, including blade walls and afterburner heat shield walls.

[0003] Film cooling is one of the most important and effective methods for cooling hot-end components of aero-engines. However, under complex flow conditions, the cooling effect and adaptability of film cooling structures face significant challenges. For example, the outlet airflow of a compact combustor exhibits significant swirling, which greatly affects the film cooling characteristics of the blade leading edge. In variable cycle engines, adjustable turbine guide vanes are subjected to changes in incoming flow rate, and the installation angle of the adjustable guide vanes can be adjusted according to the flow rate, thus challenging the applicability of film cooling structures on the blade surface.

[0004] In recent years, the impact of the combustion chamber outlet flow field on the aerodynamic and heat transfer performance of turbine blades has been extensively studied. Previous research results indicate that swirling flow leads to a reduction in turbine stage efficiency of up to 3.1%, and increases the heat load on guide vanes and rotor blades by 200% and 40%, respectively. Heat shields are widely used as thermal protection structures for afterburners and exhaust nozzles. After ignition and combustion at the afterburner head, the combustion gases generate swirling flow within the nozzle, and the mainstream area of ​​the heat shield, which is closer to the flame, is affected by this swirling flow.

[0005] Several previously disclosed afterburner heat shields include a porous corrugated plate heat shield (US005465572A). The expansion and contraction of its corrugated structure effectively prevents the effects of thermal deformation caused by the vibrating core shell, and the discrete film cooling jets on the corrugated plate can also provide film cooling to the high-temperature combustion gas side of the heat shield. However, precisely because of the corrugated structure, the cooling film jets cannot cover the entire surface, resulting in excessively high local wall temperatures and preventing effective film coverage and heat exchange. Another type is a divergent cooling heat shield structure with turbulence columns (US 20140096527A1), which forms a film covering on the wall surface through divergent cooling, blocking direct contact between the high-temperature combustion gas and the heat shield. Simultaneously, the turbulence column structure on the cold gas side wall can turbulently mix the cold gas, enhancing convective heat transfer and allowing the cold gas to carry away more heat, thus lowering the wall temperature. However, the cooling methods described above do not consider the influence of complex mainstream flows, including changes in flow angle and swirling flow. Under complex inflow conditions, the outflow and coverage characteristics of simple circular orifices and slotted orifices are affected by swirling and variable angle-of-attack flows, leading to entrainment, blowing away, and even backflow. This significantly impacts the outflow rate and wall coverage, resulting in a marked decrease in film cooling efficiency. Therefore, the adaptability of traditional film cooling orifices faces a significant challenge. In other words, existing film cooling structures have a limited range of applications. It cannot meet the high-efficiency cooling requirements of typical cooling walls such as blade leading edge, flame tube heat shield, and afterburner heat shield under complex conditions, especially swirling conditions and variable angle of attack conditions, and the amount of cold air used is also large. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide an air film hole structure and air film formation method for an engine cooling wall surface that uses an air film hole with multiple axially extended holes, which improves the adaptability of the cooling structure under complex flow conditions, maximizes the spanwise coverage area of ​​the air film, and has better air film adhesion performance.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a film cooling wall structure for an engine, including a film plate (1), on which film holes (2) are arranged in a matrix for forming a film through secondary flow to achieve heat insulation and cooling of the film plate (1). The air film hole (2) is a discontinuous annular hole composed of at least two fan-ring holes (21) and fan-ring partitions (22) for connecting the two fan-ring holes (21); The diameter of the inner ring formed by the air film hole (2) is d, the diameter of the outer ring is D, and the distance between the outer ring and the inner ring is the width B of the fan ring hole (21). Therefore, B < 0.5 D. The matrix arrangement of the air film holes (2) on the air film plate (1) is as follows: The air film plate (1) is divided into multiple area units, and the air film holes (2) are arranged in the area units. The side length of the area unit in the flow direction of the air film plate (1) is the horizontal unit length Sx, and the side length perpendicular to the flow direction is the vertical unit length Sy. Then, the opening ratio of the air film holes (2) in the area units is: The area of ​​the air film pores / Sx×Sy = 0.9~4%; The air film holes (2) are arranged continuously or alternately on the flow direction and longitudinal extension surface of the air film plate (1).

[0008] Furthermore, the air film pore (2) includes 2 to 6 fan-shaped pores (21).

[0009] Furthermore, the areas of the plurality of fan-shaped holes (21) of the air film pore (2) are equal or different, but the total area of ​​the plurality of fan-shaped holes (21) is related to the diameter d. ’ The area of ​​the circular holes is the same for diameters ranging from 0.3 to 10 mm.

[0010] Furthermore, the center point of the annulus formed by the air film holes (2) coincides with the midpoint of the area unit, that is, the air film holes (2) are located at the center of the area unit.

[0011] Furthermore, the spacing between the air film holes (2) arranged in pairs along the flow direction on the air film plate (1) is P1, the spacing between the air film holes (2) arranged in pairs along the longitudinal direction is P2, and the diameter of the circular hole with the same area as the fan ring hole (21) is d. ’ Then we have: P1=1~13d ’ P2 = 1~6d ’ .

[0012] Furthermore, the air film hole (2) is a normal through hole or a rearward expansion hole of the air film plate (1); When it is a normal through hole, the cross section of the air film hole (2) is provided with a pair of inclination angles α1=α2=90°. When the air film hole (2) is a backward expansion hole, the sum of the two inward inclination angles corresponding to the cross-section of the air film hole (2) is 90 degrees, and: 45°≤α1≤90°, 45°≤α2≤90°.

[0013] Furthermore, the fan-shaped partition (22) has a pair of arc-shaped connecting edges and a pair of parallel or inclined edges; When the sides are parallel, the distance L between the two sides is 0.1~0.2mm; When it is the inclined side, the central angle corresponding to the inclined side is θ, and the range of θ is 10~30 degrees.

[0014] Furthermore, the air film pore (2) is a discontinuous elliptical annular pore; The elliptical inner ring formed by the air film pores (2) has a longer chord length of a and a shorter chord length of b, then b < 2a.

[0015] Furthermore, the air film plate (1) is the leading edge of the engine blade or the heat shield of the combustion chamber.

[0016] The present invention also provides a method for forming a film in the film pore structure of the engine cooling wall. Secondary flow C1 flows on the upper surface of the film plate (1) and then flows into or is drawn into the film hole (2). After the airflow C2 exchanges heat with the wall of the film plate (1), it forms film outflow C3. On the one hand, it mixes with the mainstream C4 to reduce the temperature of the gas on the wall. On the other hand, the cold air forms a film on the wall to cover and block the gas from scouring the wall, reducing heat transfer. In this process, since the film hole (2) is composed of multiple fan-shaped holes (21), the secondary flow C1 can enter the film hole (2) from a wider range, and the film outflow C3 can also expand from multiple directions. This not only improves the coverage effect of the film outflow, but also has good adaptability to complex incoming flow, including swirling flow, and ensures good film cooling efficiency.

[0017] The beneficial effects of the present invention are: the air film pore structure and air film formation method of the engine cooling wall provided by the present invention effectively improve the adaptability of the air film cooling structure. Whether used on blades or combustion chamber heat insulation walls, it can maintain good cooling efficiency and thermal protection effect under complex flow conditions, and reduce the amount of cooling air used.

[0018] The structure provided by this invention includes an irregularly shaped film cooling hole with an axial through hole. The arrangement of the film cooling hole is suitable for film outflow under swirling conditions, forming an effective film coverage and avoiding the consequences of reduced cooling efficiency caused by changes in the film direction under swirling conditions, which are common with traditional circular film cooling holes, slotted holes, and other single irregularly shaped holes. On the other hand, compared with a single hole, the film coverage area of ​​the film cooling hole composed of multiple short annular fan-shaped holes is increased, improving the film cooling efficiency, effectively reducing the wall temperature, and improving the utilization rate of cold air. Attached Figure Description

[0019] Figure 1 This is a schematic cross-sectional view of the structure of the present invention; Figure 2 This is a top view of the air film pore structure of the present invention; Figure 3 This is a schematic cross-sectional view of the air film pore structure of the present invention; Figure 4 This is another schematic diagram of the top view structure of the air-supported membrane panel of the present invention; Figure 5 This is a schematic diagram of the flow field of the present invention; Figure 6 This is a comparison diagram of the cooling effect of the air film in this invention. Figure 7 This is a comparison diagram of the spanwise average film cooling effect of the present invention.

[0020] In the diagram: 1. Air-supported membrane panel; 2. Air-supported membrane hole; 21. Fan ring hole; 22. Fan ring partition. Detailed Implementation

[0021] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0022] To achieve the above objectives, the present invention provides the following specific embodiments: Example 1: As Figure 1 , Figure 2 , Figure 6 , Figure 7 As shown, an air film perforation structure for an engine cooling wall includes an air film plate 1, on which air film holes 2 are arranged in a matrix for forming an air film through secondary flow, thereby achieving heat insulation and cooling of the air film plate 1; the air film plate 1 is the leading edge of an engine blade or a heat shield for the combustion chamber.

[0023] The air film aperture 2 is a discontinuous annular aperture composed of at least two fan-ring apertures 21 and fan-ring partitions 22 for connecting the two fan-ring apertures 21; the air film aperture 2 includes 2 to 6 fan-ring apertures 21; the areas of the multiple fan-ring apertures 21 of the air film aperture 2 are equal or different, but the total area of ​​the multiple fan-ring apertures 21 is related to the diameter d. ’ The areas of the circular holes, ranging from 0.3 to 10 mm, may be the same or different.

[0024] The diameter of the inner ring formed by the air film hole 2 is d, the diameter of the outer ring is D, and the distance between the outer ring and the inner ring is the width B of the fan ring hole 21. Therefore, B < 0.5 D. The air film hole 2 is a normal through hole or a backward expansion hole of the air film plate 1; When it is a normal through hole, the cross section of the air film hole 2 is provided with a pair of inclination angles α1=α2=90°. When the air film hole 2 is a rearward expansion hole, the sum of the sum of the two inward inclination angles corresponding to the cross-section of the air film hole 2 is 90 degrees, and: 45°≤α1≤90°, 45°≤α2≤90°.

[0025] The fan-shaped partition 22 has a pair of arc-shaped connecting edges and a pair of parallel or inclined edges; When the sides are parallel, the distance L between the two sides is 0.1~0.2mm; When the side is inclined, the central angle corresponding to the inclined side is θ, and the range of θ is 10~30 degrees.

[0026] The matrix arrangement of the air film pores 2 on the air film plate 1 is as follows: The air-supported film plate 1 is divided into multiple area units, and air-supported film holes 2 are set in the area units. The side length of the area unit in the flow direction of the air-supported film plate 1 is the horizontal unit length Sx, and the side length perpendicular to the flow direction is the vertical unit length Sy. Then, the opening ratio of the air-supported film holes 2 in the area unit is: The area of ​​the air film pores / Sx×Sy = 0.9~4%; The spacing between the air film holes 2 arranged in pairs along the flow direction on the air film plate 1 is P1, and the spacing between the air film holes 2 arranged in pairs along the longitudinal direction is P2. The diameter of the circular hole with the same area as the fan ring hole 21 is d. ’ Then we have: P1=1~13d ’ P2 = 1~6d ’ ; The air film holes 2 are continuously or staggeredly extended on the flow direction and longitudinal extension surface of the air film plate 1. The center point of the ring formed by the air film holes 2 coincides with the midpoint of the area unit, that is, the air film holes 2 are set at the center of the area unit.

[0027] like Figure 6 , Figure 7 As shown, based on the same air film plate opening ratio and with consistent flow parameters, the air film cooling efficiency of this novel air film pore structure and the circular air film pore structure are compared. The air film cooling efficiency cloud diagram is shown below. Figure 6 As shown, the spanwise average film cooling effect is compared to... Figure 7 As shown.

[0028] As can be seen from the figure, compared with traditional circular film cooling holes, annular film cooling holes improve film cooling efficiency. Furthermore, with the reduced area of ​​a single fan-shaped annular hole 21, the film adherence to the wall improves, and the film coverage area increases in both the longitudinal and flow directions, resulting in a significant increase in overall film cooling efficiency. Figure 7 As can be seen, when the blowing ratio is 0.8, the air film cooling efficiency of the air film pores provided by the present invention is improved by up to 20% in local locations compared with that of circular air film pores.

[0029] Example 2: Figure 2 As shown in (a), it is the same as in Example 1, except that: the air film hole 2 is a discontinuous annular hole composed of four fan ring holes 21 and fan ring partitions 22 for connecting two fan ring holes 21; the multiple fan ring holes 21 of the air film hole 2 have the same area.

[0030] Example 3: As Figure 2 As shown in (b), it is the same as in Example 1, except that: the air film hole 2 is a discontinuous annular hole composed of three fan ring holes 21 and fan ring partitions 22 for connecting two fan ring holes 21; the multiple fan ring holes 21 of the air film hole 2 have the same area.

[0031] Example 4: Figure 2 As shown in (c), it is the same as in Example 1, except that: the air film hole 2 is a discontinuous annular hole composed of four fan ring holes 21 and fan ring partitions 22 for connecting two fan ring holes 21; the multiple fan ring holes 21 of the air film hole 2 have different areas.

[0032] Example 5: Figure 2 As shown in (d), it is the same as in Example 1, except that: the air film hole 2 is a discontinuous elliptical annular hole; the elliptical inner ring formed by the air film hole 2 has a longer chord length of a and a shorter chord length of b, then: b < 2a.

[0033] Example 6: As Figure 3 As shown in (a), it is the same as in Example 1, except that: the air film hole 2 is a pair of inward inclination angles α1=α2=90° corresponding to the cross section of the air film hole 2 of the air film plate 1.

[0034] Example 7: Figure 3 As shown in (b), the method is the same as in Example 1, except that: the air film hole 2 is the rearward expansion hole of the air film plate 1, and the sum of the two inward inclination angles corresponding to the cross-section of the air film hole 2 is 90 degrees, and: 45°≤α1≤90°, 45°≤α2≤90°.

[0035] Example 8: As Figure 4 As shown in (a), it is the same as in Example 1, except that the fan ring partition 22 has a pair of arc-shaped connecting edges and a pair of parallel edges, and the distance L between the two edges is 0.1~0.2mm.

[0036] Example 9: As Figure 4 As shown in (b), it is the same as in Example 1, except that the fan ring partition 22 has a pair of arc-shaped connecting edges and a pair of inclined edges, and the central angle corresponding to the inclined edge is θ, with θ ranging from 10 to 30 degrees.

[0037] Example 10: As Figure 5 As shown, the present invention also provides a method for forming a film in the film pore structure of an engine cooling wall: Secondary flow C1 flows on the upper surface of the film plate 1 and then flows into or is drawn into the film orifice 2. After the airflow C2 exchanges heat with the wall of the film plate 1, it forms a film outflow C3. On the one hand, it mixes with the mainstream C4 to reduce the temperature of the combustion gas on the wall. On the other hand, the cold air forms a film on the wall to cover and block the combustion gas from scouring the wall, reducing heat transfer. In this process, since the film orifice 2 is composed of multiple fan-shaped holes 21, the secondary flow C1 can enter the film orifice 2 from a wider range, and the film outflow C3 can also expand from multiple directions. This not only improves the coverage effect of the film outflow, but also has good adaptability to complex incoming flows, including swirling flows, ensuring good film cooling efficiency.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A film cooling hole structure for an engine cooling wall, characterized in that, Includes an air film plate (1), on which air film plates (1) are arranged in a matrix of air film holes (2) for forming an air film through a secondary flow to achieve heat insulation and cooling of the air film plate (1); The air film hole (2) is a discontinuous annular hole composed of at least two fan-ring holes (21) and fan-ring partitions (22) for connecting the two fan-ring holes (21); The diameter of the inner ring formed by the air film hole (2) is d, the diameter of the outer ring is D, and the distance between the outer ring and the inner ring is the width B of the fan ring hole (21). Therefore, B < 0.5 D. The matrix arrangement of the air film holes (2) on the air film plate (1) is as follows: The air film plate (1) is divided into multiple area units, and the air film holes (2) are arranged in the area units. The side length of the area unit in the flow direction of the air film plate (1) is the horizontal unit length Sx, and the side length perpendicular to the flow direction is the vertical unit length Sy. Then, the opening ratio of the air film holes (2) in the area units is: The area of ​​the air film pores / Sx×Sy = 0.9~4%; The air film holes (2) are arranged continuously or alternately on the flow direction and longitudinal extension surface of the air film plate (1).

2. The film cooling wall structure as described in claim 1, characterized in that, The air film pore (2) includes 2 to 6 fan-shaped pores (21).

3. The film cooling wall structure as described in claim 1, characterized in that, The areas of the multiple fan-ring holes (21) of the air film pore (2) are equal or different, but the total area of ​​the multiple fan-ring holes (21) is equal to the diameter d. ’ The area of ​​the circular holes is the same for diameters ranging from 0.3 to 10 mm.

4. The film cooling wall structure as described in claim 1, characterized in that, The center point of the annulus formed by the air film holes (2) coincides with the midpoint of the area unit, that is, the air film holes (2) are located at the center of the area unit.

5. The film cooling wall structure as described in claim 1, characterized in that, The spacing between the air film holes (2) arranged in pairs along the flow direction on the air film plate (1) is P1, and the spacing between the air film holes (2) arranged in pairs along the longitudinal direction is P2. The diameter of the circular hole with the same area as the fan ring hole (21) is d. ’ Then we have: P1=1~13d ’ ;P2=1~6d ’ 。 6. The film cooling wall structure as described in claim 1, characterized in that, The air film hole (2) is a normal through hole or a rearward expansion hole of the air film plate (1); When it is a normal through hole, the cross section of the air film hole (2) is provided with a pair of inclination angles α1=α2=90°. When the air film hole (2) is a backward expansion hole, the sum of the two inward inclination angles corresponding to the cross-section of the air film hole (2) is 90 degrees, and: 45°≤α1≤90°，45°≤α2≤90°。 7. The film cooling wall structure as described in claim 1, characterized in that, The fan-shaped partition (22) has a pair of arc-shaped connecting edges and a pair of parallel or inclined edges; When the sides are parallel, the distance L between the two sides is 0.1~0.2mm; When it is the inclined side, the central angle corresponding to the inclined side is θ, and the range of θ is 10~30 degrees.

8. The film cooling wall structure as described in claim 1, characterized in that, The air film pore (2) is a discontinuous elliptical annular pore; The elliptical inner ring formed by the air film pores (2) has a longer chord length of a and a shorter chord length of b, then b < 2a.

9. The film cooling wall structure of the engine as described in any one of claims 1-8, characterized in that, The air film plate (1) is the leading edge of the engine blade or the heat shield of the combustion chamber.

10. The method for forming a film in the film pore structure of the engine cooling wall as described in any one of claims 1 to 8, characterized in that, Secondary flow C1 flows on the upper surface of the film plate (1) and then flows into or is drawn into the film hole (2). After the airflow C2 exchanges heat with the wall of the film plate (1), it forms film outflow C3. On the one hand, it mixes with the mainstream C4 to reduce the temperature of the gas on the wall. On the other hand, the cold air forms a film on the wall to cover and block the gas from scouring the wall, reducing heat transfer. In this process, since the film hole (2) is composed of multiple fan-shaped holes (21), the secondary flow C1 can enter the film hole (2) from a wider range, and the film outflow C3 can also expand from multiple directions. This not only improves the coverage effect of the film outflow, but also has good adaptability to complex incoming flow, including swirling flow, and ensures good film cooling efficiency.

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