Cooling structure provided with trapezoidal air film holes and turbine blade

Abstract

The invention provides a cooling structure provided with trapezoidal air film holes. The cooling structure comprises a base body, and the air film holes extending in the first direction inclined to the thickness direction of the base body are formed in the base body; an air inlet of the air film hole is formed in a first surface of the base body, an air outlet of the air film hole is formed in a second surface, opposite to the first surface, of the base body, and a straight section and an expansion section are sequentially arranged between the air inlet and the air outlet; in the orthographic projection orthogonal to the first direction, the straight section forms a trapezoidal hole structure, the bottom edge of the trapezoidal hole structure right faces the airflow flowing direction, and the vertical distance between the upstream wall and the downstream wall of the straight section is larger than the width of the upstream wall and the width of the downstream wall in the straight section. The expansion section is constructed to expand towards the two sides in the width direction of the straight section in a widening mode to form an air outlet, so that the injection effect of the air inlet is restrained, and the range of a low momentum area near the downstream wall of the air outlet is narrowed.

Description

Technical Field

[0001] At least one embodiment of the present disclosure relates to the technical field of gas turbines, and more specifically, to a cooling structure and a turbine blade equipped with trapezoidal film holes. Background Art

[0002] The increase in turbine inlet temperature can effectively improve the overall efficiency of the gas turbine. The turbine inlet temperature of advanced gas turbines has far exceeded the temperature limit that high-temperature alloys can withstand. In order to ensure the stable operation of the gas turbine, it is necessary to cool the high-temperature components of the gas turbine. Film cooling is an efficient and mature cooling technology that has been widely used in the field of gas turbines. The basic principle of film cooling is to extract low-temperature air from the compressor and transport it to the high-temperature parts of the turbine that need to be cooled. The low-temperature gas flows out through discrete film holes and covers the wall surface, isolating the wall surface from the high-temperature mainstream while taking away part of the heat, thereby achieving the purpose of reducing the wall temperature and realizing the safe operation of the gas turbine.

[0003] At present, the most widely used hole type in gas turbines is the cylindrical film hole, and its processing technology is also the most mature. The cylindrical film hole has the advantages of simple structure, low thermal stress, and easy processing, but at the same time, the cylindrical film hole also has a series of obvious disadvantages, such as small film coverage area, high jet outlet velocity under high blowing ratio, easy to detach from the wall, low film cooling effect, large mixing loss, etc. The cylindrical film hole can meet a certain degree of cooling needs, but with the continuous increase in turbine inlet temperature, the cylindrical film hole can no longer provide sufficient cooling protection for the high-temperature components of the gas turbine. In response to the above problems, domestic and foreign scholars have carried out a lot of research to improve the performance of film cooling, and the research on the hole type of film cooling is one of the important directions. In the past few decades, a large number of novel film cooling structures or hole types have been proposed. Among the many novel film cooling structures, the outlet expansion hole is the most representative and practical. At present, advanced gas turbine blades (suction side, pressure side, end wall) have been using a large number of special-shaped film holes instead of cylindrical film holes. Among them, fan-shaped film holes have been widely used in gas turbine blades. In order to match the increase in turbine front temperature caused by the improvement of gas turbine performance, it is necessary to develop a film hole structure with better cooling effect to meet the cooling needs.

[0004] Although the fan-shaped film holes improve the film cooling effect to a certain extent, there are still problems such as the deviation of the film trajectory and the reduction of the film coverage under high blowing ratio. In order to improve the film cooling effect of turbine blades, a more suitable film hole structure needs to be developed to meet the cooling needs. Summary of the invention

[0005] In order to solve at least one of the above-mentioned and other technical problems in the prior art, the present disclosure provides a cooling structure and a turbine blade equipped with trapezoidal air film holes. By reasonably configuring the distance between the upstream wall and the downstream wall of the straight section of the air film hole and the width of the upstream and downstream walls, the injection effect of the air film hole inlet is suppressed, the range of the low momentum zone near the downstream wall of the air film hole outlet is reduced, the wall adhesion of the air film is improved, and the coverage range of the air film is expanded.

[0006] According to an embodiment of the present disclosure, there is provided, on one hand, a cooling structure equipped with trapezoidal air film holes, comprising a substrate, wherein the substrate is provided with air film holes extending along a first direction inclined to a thickness direction of the substrate; an air inlet of the air film hole is formed on a first surface of the substrate, and an air outlet of the air film hole is formed on a second surface of the substrate opposite to the first surface, and a straight section and an expansion section are sequentially arranged between the air inlet and the air outlet; wherein, in an orthographic projection orthogonal to the first direction, the straight section forms a trapezoidal hole structure, the bottom edge of which is directly opposite to the flow direction of the air flow, and the vertical distance between the upstream and downstream walls of the straight section is greater than the width of the upstream wall and the downstream wall of the straight section, so as to suppress the injection effect of the air inlet and reduce the range of the low momentum zone near the downstream wall of the air outlet; the expansion section is constructed to gradually expand toward both sides along the width direction of the straight section to form the air outlet, so as to reduce the momentum of the air flow at the air outlet.

[0007] According to an embodiment of the present disclosure, the ratio of the vertical distance between the upstream wall and the downstream wall of the straight section to the width of the upstream wall and the downstream wall of the straight section is between 1.5-6.

[0008] According to an embodiment of the present disclosure, the air outlet is configured as a trapezoidal hole structure.

[0009] According to an embodiment of the present disclosure, the injection angle of the air film hole is between 30° and 60°.

[0010] According to an embodiment of the present disclosure, the extension direction of the center line of the above-mentioned expansion section is configured to coincide with the extension direction of the center line of the above-mentioned straight section.

[0011] According to an embodiment of the present disclosure, in an orthographic projection orthogonal to the first direction, the straight section is an isosceles trapezoidal hole structure.

[0012] According to an embodiment of the present disclosure, the expansion angle of the expansion section is between 10° and 30°.

[0013] According to an embodiment of the present disclosure, the length of the straight section along the first direction is configured to be 1 / 3 to 1 / 2 of the total length of the air film hole.

[0014] On the other hand, an embodiment of the present disclosure also provides a turbine blade having a cooling structure as in the above embodiment, including a blade formed by a substrate, a gas flow channel for accommodating the passage of cooling gas being arranged in the blade, a plurality of air film holes being arranged in the blade, an air inlet of the air film holes being connected to the gas flow channel to guide the cooling gas to pass through the air film holes, and to flow out through the air outlet of the air film holes and form an air film on at least a portion of the surface of the blade.

[0015] According to an embodiment of the present disclosure, the plurality of film holes are arranged at intervals on the blade along the airflow direction and / or airflow span direction of the cooling air to form an air film hole array.

[0016] According to the cooling structure and turbine blade provided by the present invention and equipped with trapezoidal air film holes, the straight section of the air film hole is constructed into a trapezoidal hole structure, the bottom edge of which is opposite to the airflow direction, and the vertical distance between the upstream walls of the straight section is greater than the width of the upstream wall and the downstream wall of the straight section. The vertical distance between the upstream wall and the downstream wall of the straight section of the air film hole is relatively large, which weakens the injection effect of the inlet, thereby reducing the range of the low momentum zone caused by the inlet injection effect near the downstream wall, so that the cooling air is concentrated near the upstream wall, and the strength of the outlet anti-kidney vortex pair is significantly weakened, which suppresses the lateral deflection of the cooling air to the side of the air film hole outlet under high blowing ratio, and increases the width of the air film coverage; in addition, by constructing the expansion section to expand gradually to both sides along the width direction of the trapezoidal straight section to form an air outlet, the outlet area is significantly increased, the injection momentum of the cooling air is reduced, and the wall adhesion of the air film is enhanced. Furthermore, due to the weakening of the strength of the anti-kidney vortex pair and the concentration of cooling gas near the upstream wall, the outlet lateral expansion angle can be greatly increased to obtain a wide and uniform downstream air film coverage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of a cooling structure with fan-shaped air film holes in the prior art, wherein: Figure 1 A shows a top view of a cooling structure equipped with fan-shaped air film holes. Figure 1 B shows a cross-sectional view of a cooling structure provided with fan-shaped air film holes;

[0018] Figure 2 is a schematic diagram of a cooling structure equipped with trapezoidal air film holes according to an exemplary embodiment of the present disclosure, wherein: Figure 2 A shows a top view of a cooling structure equipped with trapezoidal air film holes. Figure 2 B shows a cross-sectional view of a cooling structure equipped with trapezoidal air film holes. Figure 2 C shows an orthographic projection of the cooling structure provided with trapezoidal air film holes from a C-direction viewing angle;

[0019] Figure 3is a schematic diagram of a cooling structure equipped with trapezoidal air film holes according to another exemplary embodiment of the present disclosure, wherein: Figure 3 A shows a top view of a cooling structure equipped with trapezoidal air film holes. Figure 3 B shows an orthographic projection of the cooling structure equipped with trapezoidal air film holes from a C-direction viewing angle;

[0020] Figure 4 yes Figure 2 A comparison diagram of the flow field in the hole formed by the cooling structure with trapezoidal air film holes in the exemplary embodiment and the cooling structure with fan-shaped air film holes in the prior art;

[0021] Figure 5 yes Figure 2 The illustrated exemplary embodiment is a three-dimensional view of an air film hole array formed by a plurality of air film holes.

[0022] In the drawings, the meanings of the reference numerals are as follows:

[0023] 1. Air film hole;

[0024] 11. Straight section;

[0025] 111, upstream wall of the straight section;

[0026] 112, downstream wall of the straight section;

[0027] 12. Expansion section;

[0028] 2. Matrix;

[0029] 21. First page;

[0030] 22. Second side. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0032] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0033] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0034] When using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, and C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc. When using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, or C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.

[0035] Figure 1 Schematic diagram of a cooling structure with fan-shaped air film holes in the prior art, wherein: Figure 1 A shows a top view of a cooling structure equipped with fan-shaped air film holes. Figure 1 B shows a cross-sectional view of a cooling structure provided with fan-shaped air film holes.

[0036] In film cooling technology, fan-shaped film holes are a common hole shape used in gas turbine film cooling technology. Figure 1 As shown in the figure, the fan-shaped film hole has a laterally expanded rear half of the film hole based on the cylindrical film hole. The fan-shaped film hole can be divided into a straight section and an expansion section along the cooling gas flow direction. The total length of the film hole is L, of which the length of the straight section is Lt. The cross-sectional shape of the straight section of the fan-shaped film hole is circular with a diameter of D. The lateral expansion angle of the expansion section is γ. Although the fan-shaped film hole improves the film cooling effect to a certain extent, under high blowing ratios, the cooling gas jet easily detaches from the wall and deflects laterally to the side of the hole outlet, the film coverage width is reduced, the film cooling effect is deteriorated, and sufficient cooling film protection can no longer be provided. This phenomenon is more obvious in high mainstream flow velocity areas such as the suction surface of the turbine blade.

[0037] To this end, based on the above-mentioned deficiencies in the prior art, how to design the air film holes, reasonably design the geometric structure and aspect ratio of the straight section and the expansion section, suppress the injection effect at the air inlet and the deviation of the air film trajectory at the air outlet, and ensure the air film coverage range has become a technical problem that needs to be solved urgently.

[0038] In view of this, an embodiment of the present disclosure provides a cooling structure and a turbine blade equipped with trapezoidal film holes.

[0039] Figure 2 is a schematic diagram of a cooling structure equipped with trapezoidal air film holes according to an exemplary embodiment of the present disclosure, wherein: Figure 2A shows a top view of a cooling structure equipped with trapezoidal air film holes. Figure 2 B shows a cross-sectional view of a cooling structure equipped with trapezoidal air film holes. Figure 2 FIG. C shows an orthographic projection of the cooling structure provided with trapezoidal air film holes from a viewing angle in the C direction.

[0040] According to a cooling structure provided by the present disclosure and having trapezoidal air film holes, Figure 2 As shown, it includes a substrate, and the substrate 2 is provided with an air film hole 1 extending along a first direction inclined to the thickness direction of the substrate. The air inlet of the air film hole 1 is formed on the first surface 21 of the substrate 2, and the air outlet of the air film hole 1 is formed on the second surface 22 of the substrate opposite to the first surface 21. A straight section 11 and an expansion section 12 are sequentially arranged between the air inlet and the air outlet. Among them, in the orthographic projection orthogonal to the first direction, the straight section 11 forms a trapezoidal hole structure, and its bottom edge is directly opposite to the direction of the air flow. The vertical distance between the upstream and downstream walls of the straight section 11 is greater than the width of the upstream wall and the downstream wall of the straight section to suppress the injection effect of the air inlet and reduce the range of the low momentum zone near the downstream wall of the air outlet. The expansion section 12 is constructed to expand gradually along the width direction of the straight section 11 to form an air outlet, so as to reduce the momentum of the air flow at the air outlet.

[0041] According to the above-mentioned setting mode, the vertical distance H between the upstream and downstream walls of the straight section 11 is greater than the width of the upstream wall 111 and the downstream wall 112 of the straight section. The vertical distance H between the upstream wall 111 and the downstream wall 112 of the straight section of the air film hole 1 is relatively large, which can effectively reduce the flow velocity gradient caused by the inlet jet effect, thereby suppressing the jet effect at the air inlet, thereby reducing the range of the low momentum area caused by the inlet jet effect near the downstream wall 112, which also substantially increases the range of the high momentum area near the upstream wall in the air film hole. Due to the increase in the range of the high momentum area in the air film hole, the velocity gradient with the high-temperature mainstream gas at the air film hole outlet is reduced, thereby weakening the anti-kidney vortex pair at the air outlet. Under high blowing ratio, the overly strong anti-kidney vortex pair may cause the cooling air to be blown away from the wall, resulting in reduced cooling efficiency. The above-mentioned setting ensures that the anti-kidney vortex pair can be within a reasonable strength range, effectively suppressing the lateral deviation of the cooling air to the side of the air outlet under high blowing ratio, and obtaining a wide and uniform downstream air film coverage, thereby ensuring the efficiency of air film cooling. Since the expansion section 12 widens to both sides along the width direction of the trapezoidal straight section 11, and the vertical distance H between the upstream wall and the downstream wall is relatively large, the corresponding width of the air outlet flow direction is also relatively large, so that the air outlet has a larger area, reducing the momentum of the cooling air at the air outlet, improving the wall adhesion of the cooling air, and expanding the coverage of the air film.

[0042] In this embodiment, the air film hole 1 is suitable for transporting cooling air to the high-temperature part of the turbine that needs to be cooled.

[0043] In this embodiment, the base 2 is the suction surface, pressure surface or end wall of a turbine blade.

[0044] In this embodiment, the cooling gas is air or compressor guide air.

[0045] In this embodiment, the air film holes are obtained by laser drilling, electric spark drilling, etc.

[0046] In an illustrative embodiment, the ratio of the vertical distance H between the upstream wall 111 and the downstream wall 112 of the straight section 11 to the diameter D of the straight section of the fan-shaped air film hole with the same cross-sectional area in the prior art, that is, H / D, is between 1.2-2.0.

[0047] According to the above-mentioned setting method, it can be ensured that there is a suitable vertical distance H between the upstream wall and the downstream wall of the straight section of the air film hole in the present disclosure, so as to effectively suppress the inlet injection effect and improve the cooling efficiency.

[0048] In an illustrative embodiment, Figure 2 As shown, the width W1 of the upstream wall 111 of the straight section is smaller than the width W2 of the downstream wall 112 .

[0049] According to the above arrangement, from the C-direction perspective, the cross section of the straight section of the film hole is a regular trapezoid with a large aspect ratio, the upstream wall of the film hole is the short bottom side with a smaller length in the trapezoidal cross section, and the downstream wall is the long bottom side with a larger length in the trapezoidal cross section. Since the upstream wall is narrower in the straight section, the high momentum area is more concentrated near the center line of the film hole, thereby improving the cooling effect near the center line of the film hole.

[0050] Figure 3 is a schematic diagram of a cooling structure equipped with trapezoidal air film holes according to another exemplary embodiment of the present disclosure, wherein: Figure 3 A shows a top view of a cooling structure equipped with trapezoidal air film holes. Figure 3 B shows an orthographic projection of the cooling structure equipped with trapezoidal air film holes from a viewing angle of direction C.

[0051] In an illustrative embodiment, Figure 3 As shown, the width W1 of the upstream wall 111 of the straight section is greater than the width W2 of the downstream wall 112 .

[0052] According to the above arrangement, from the C-direction perspective, the cross section of the straight section of the air film hole is an inverted trapezoid, the upstream wall of the air film hole is the longer bottom side of the trapezoidal cross section, and the downstream wall is the shorter bottom side of the trapezoidal cross section. Since the upstream wall is wider, the high momentum area in the air film hole is distributed more widely, so a wider air film coverage range can be obtained.

[0053] In an illustrative embodiment, Figure 2 As shown, the ratio of the vertical distance H between the upstream wall and the downstream wall of the straight section to the width W1 of the upstream wall 111 and the width W2 of the downstream wall 112 of the straight section is between 1.5-6.

[0054] According to the above arrangement, it can be ensured that the vertical distance H between the upstream wall 111 and the downstream wall 112 of the straight section is relatively large, thereby ensuring the suppression effect of the inlet injection effect.

[0055] In an illustrative embodiment, Figure 2 As shown, the air outlet is configured as a trapezoidal hole structure.

[0056] According to the above arrangement, after the air film hole is expanded through the expansion section, the outlet width and outlet area are significantly increased, the cooling gas injection momentum is greatly reduced, the wall adhesion of the cooling gas is improved, and the coverage of the air film is expanded.

[0057] In an illustrative embodiment, Figure 2 As shown, the angle α between the flow direction of the cooling gas ejected from the air film hole of the present invention and the surface of the cooled substrate is called the injection angle, which is between 30° and 60°. Depending on the different use positions of the cooling hole structure, the degree of α can be adjusted according to actual conditions.

[0058] According to the above arrangement, it is helpful to enhance the wall adhesion and stability of the air film, and because the cooling gas jet forms a certain angle with the substrate 2, its flow path is longer, which increases the contact area with the surface of the cooled substrate, thereby improving the cooling effect.

[0059] In an illustrative embodiment, Figure 2 As shown, the extension direction of the center line of the expansion section 12 is configured to coincide with the extension direction of the center line of the straight section 11 .

[0060] According to the above arrangement, the stable flow of the cooling airflow in the air film holes can be ensured, thereby avoiding energy loss or turbulence caused by the change of the axis of the airflow channel.

[0061] In an illustrative embodiment, Figure 2 As shown, in the orthographic projection perpendicular to the first direction, the straight section 11 is an isosceles trapezoidal hole structure.

[0062] According to the above arrangement, since the straight section 11 is bilaterally symmetrical, the flow of the cooling gas in the hole can be made more uniform, thereby ensuring the cooling efficiency.

[0063] In an illustrative embodiment, Figure 2 As shown, the expansion angle of the expansion section is between 10° and 30°.

[0064] According to the above-mentioned setting method, the air film hole can obtain a wider outlet width and a larger outlet area along the expansion section to improve the wall adhesion of the cooling gas and expand the coverage of the air film. Since the air film hole of the present disclosure weakens the influence of the injection effect at the air inlet, flow separation is not easy to occur in the expansion section. Therefore, compared with the general air film hole, the expansion angle of the air film hole structure in the present disclosure can be appropriately increased.

[0065] In an illustrative embodiment, Figure 2 As shown, the length of the straight section 11 along the first direction is configured to be 1 / 3 to 1 / 2 of the total length of the air film hole 1 .

[0066] According to the above-mentioned setting method, it can be ensured that the cooling gas passing through the air film hole has sufficient momentum in the straight section 11 so that it can effectively form an air film at the air outlet. By reasonably setting the length of the expansion section 12, it is ensured that the momentum of the cooling gas at the air outlet is reduced to a reasonable range, so as to expand the coverage of the air film, improve the wall adhesion of the air film, prevent the air film from detaching, and ensure the efficiency of the air film cooling.

[0067] Figure 4 yes Figure 2 A comparison diagram of the flow field in the hole formed in the flow field of the cooling structure equipped with trapezoidal air film holes in the schematic embodiment shown and the cooling structure equipped with fan-shaped air film holes in the prior art.

[0068] In order to more intuitively illustrate the problem that can be solved by the cooling structure provided by the present disclosure with the trapezoidal air film holes, Figure 4 The flow conditions of cooling air in the common fan-shaped air film holes in the prior art and the trapezoidal air film holes in the embodiment of the present disclosure are given in FIG. In the present embodiment, the cross-sectional area of ​​the trapezoidal air film holes and the straight section of the fan-shaped air film holes along the C direction are the same.

[0069] like Figure 4As shown in the figure, it can be seen that when the cooling gas enters the film cooling hole, a jet effect occurs at the cooling gas inlet due to the large angle of deflection. Under the influence of the jet effect, there are obvious differences in the distribution of cooling gas in different film hole structures. In the fan-shaped film hole, due to the small distance between the upstream wall and the downstream wall of the film hole, the range of the low momentum area near the downstream wall is relatively large, and the intensity of the anti-kidney vortex downstream of the film hole outlet is relatively large. From the flow conditions of the outlet cross section, the range of high momentum cooling gas in the hole is small and distributed on both sides of the hole. Combined with the high-strength anti-kidney vortex structure downstream, the cooling gas is laterally deflected to the side of the hole outlet under high blowing ratio. The vertical distance between the upstream wall and the downstream wall of the air film hole structure in the embodiment of the present disclosure is larger than that of the fan-shaped air film hole, and the low momentum area near the downstream wall accounts for a smaller proportion. The main cooling gas is distributed near the upper wall of the air film hole. Since it is less affected by the downstream wall vortex, the high-speed cooling gas flow near the upstream wall will be more uniform, so the outlet lateral expansion angle can be greatly increased to obtain a wide and uniform downstream air film coverage. From the flow conditions of the outlet cross section, it can be seen that in the embodiment of the present disclosure, there is a large range of high-momentum cooling gas near the upstream wall, which, combined with the anti-kidney vortex pair with weakened strength, effectively suppresses the lateral deflection of the cooling gas to the side of the hole outlet under high blowing ratios. In addition, compared with the fan-shaped air film hole, the outlet area of ​​the air film hole in the embodiment of the present disclosure is greatly increased, the cooling gas injection momentum is weakened, it is not easy to separate from the wall under high blowing ratios, and the air film is more adherent to the wall.

[0070] The present disclosure also provides a turbine blade with the above-mentioned cooling structure, including a blade formed by a substrate, a gas flow channel for accommodating the passage of cooling gas is arranged in the blade, and a plurality of air film holes 1 are arranged in the blade, and the air inlet of the air film hole 1 is connected to the gas flow channel to guide the cooling gas to pass through the air film hole 1, and flow out through the air outlet of the air film hole 1 and form an air film on at least a part of the surface of the blade.

[0071] According to the above-mentioned setting method, the cooling gas forms an air film on at least a part of the surface of the turbine blade through the air film holes, which can prevent problems such as material damage caused by excessive temperature, thereby improving the performance and life of the turbine and reducing operating costs.

[0072] Figure 5 yes Figure 2 The illustrated exemplary embodiment is a three-dimensional view of an air film hole array formed by a plurality of air film holes.

[0073] In an illustrative embodiment, Figure 5 As shown, a plurality of film holes 1 are arranged at intervals on the blade along the airflow direction and / or airflow span direction of the cooling air to form an array of film holes 1.

[0074] According to the above arrangement, by arranging an array of air film holes on the upper edge of the turbine blade, the high temperature area on the turbine blade that needs to be cooled can be effectively covered with a cooling air film to prevent the turbine blade from being overheated.

[0075] In this embodiment, referring to the fan-shaped air film holes with the same straight section cross-sectional area in the prior art, the lateral spacing between two adjacent air film holes is P, and the hole spacing P is not less than 6D.

[0076] Based on the above technical solution, the cooling structure and turbine blade equipped with trapezoidal air film holes of the present invention have one or part of the following beneficial effects:

[0077] 1. Since the vertical distance between the upstream wall and the downstream wall is significantly enlarged, the inlet jet effect can be effectively weakened and the range of the low momentum area near the downstream wall caused by the inlet jet effect can be reduced.

[0078] 2. Due to the relative reduction of low-momentum fluid near the downstream wall, the intensity of the anti-kidney vortex at the outlet can be weakened, and the lateral deflection of the cooling air to the side of the hole outlet under high blowing ratio can be suppressed.

[0079] 3. Due to the long lateral expansion of the side wall based on the trapezoidal straight section, the outlet area is significantly increased, the injection momentum of the cooling gas outlet is significantly reduced, and the air film has strong wall adhesion.

[0080] 4. Since the high-speed cooling gas is concentrated on the upstream wall of the air film hole, the mixing loss between the cooling gas and the mainstream is reduced.

[0081] 5. Since the downstream wall vortex has less influence, the high-speed cooling air flows more evenly near the upstream wall, which can greatly increase the outlet lateral expansion angle and obtain a wide and uniform downstream air film coverage.

[0082] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure.

[0083] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A cooling structure equipped with trapezoidal air film holes, characterized in that: It comprises a substrate, wherein the substrate is provided with air film holes extending along a first direction inclined with respect to a thickness direction of the substrate; The air inlet of the air film hole is formed on the first surface of the substrate, and the air outlet of the air film hole is formed on the second surface of the substrate opposite to the first surface, and a straight section and an expansion section are sequentially arranged between the air inlet and the air outlet; Wherein, in the orthographic projection orthogonal to the first direction, the straight section forms a trapezoidal hole structure, the bottom side of which is directly opposite to the airflow direction, and the vertical distance between the upstream and downstream walls of the straight section is greater than the width of the upstream wall and the downstream wall of the straight section, so as to suppress the injection effect of the air inlet and reduce the range of the low momentum zone near the downstream wall of the air outlet; The expansion section is configured to expand gradually toward both sides along the width direction of the straight section to form the air outlet, so as to reduce the momentum of the airflow at the air outlet.

2. The cooling structure according to claim 1, characterized in that: The ratio of the vertical distance between the upstream wall and the downstream wall of the straight section to the width of the upstream wall and the downstream wall of the straight section is between 1.5 and 6.

3. The cooling structure according to claim 1, characterized in that: The air outlet is configured as a trapezoidal hole structure.

4. The cooling structure according to claim 1, characterized in that: The spray angle of the air film hole is between 30° and 60°.

5. The cooling structure according to any one of claims 1 to 4, characterized in that: The extension direction of the center line of the expansion section is configured to coincide with the extension direction of the center line of the straight section.

6. The cooling structure according to claim 5, characterized in that: In an orthographic projection perpendicular to the first direction, the straight section is an isosceles trapezoidal hole structure.

7. The cooling structure according to claim 6, characterized in that: The expansion angle of the expansion section is between 10° and 30°.

8. The cooling structure according to claim 7, characterized in that: The length of the straight section along the first direction is configured to be 1 / 3 to 1 / 2 of the total length of the air film hole.

9. A turbine blade having a cooling structure as claimed in any one of claims 1 to 8, characterized in that: It includes a blade formed by a substrate, wherein a gas flow channel for accommodating the passage of cooling gas is arranged in the blade, and a plurality of air film holes are arranged in the blade, wherein the air inlet of the air film holes is connected to the gas flow channel to guide the cooling gas to pass through the air film holes, and flow out through the air outlet of the air film holes to form an air film on at least a portion of the surface of the blade.

10. The turbine blade according to claim 9, characterized in that The plurality of film holes are arranged at intervals on the blade along the airflow direction and / or airflow span direction of the cooling air to form an air film hole array.

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