Hole and groove combined discrete air film cooling structure and turbine blade

Abstract

The invention provides a hole-groove combined discrete air film cooling structure and a turbine blade, the discrete air film cooling structure comprises a plurality of cold air inlets, each cold air inlet comprises at least two air film holes distributed discretely, the aperture of each air film hole is smaller than the diameter of the cross section of a standard cylindrical hole, and the air film holes are used for introducing cold air; each air film hole is sequentially communicated with a straight section cold air channel and an expansion section cold air channel; the expansion section cold air channel, corresponding to the adjacent air film hole, in each cold air inlet is communicated through a connecting structure plane at the position away from the outlet end by a preset distance, a groove-shaped structure is formed at the outlet end, and the expansion section cold air channel and the groove-shaped structure are used for enlarging the coverage width of sprayed cold air. According to the discrete air film cooling structure, the air film coverage width of an outlet can be remarkably enlarged, a multi-peak air film form is formed at the outlet, and the air film cooling effect is remarkably improved under the condition that the cold air amount is not increased.

Description

Technical Field

[0001] The invention relates to the technical field of gas turbines, and in particular to a hole-slot combined discrete air film cooling structure and a turbine blade. Background Art

[0002] Gas turbines are widely used in aircraft propulsion, land power generation and various industrial purposes. They are an indispensable power device for a country's development. For gas turbines, increasing the turbine inlet temperature can improve the overall efficiency of the gas turbine, so the increase in turbine inlet temperature is an inevitable trend in the development of gas turbines. At present, the turbine inlet temperature has far exceeded the melting point of the alloy material used for the blades. The improvement of the temperature resistance of high-temperature alloys and the development of thermal barrier coating technology can no longer meet the needs of improving the efficiency of gas turbines. Therefore, advanced blade cooling technology has become a key determinant for the stable operation of gas turbines and further improvement of efficiency.

[0003] Film cooling plays an important role in the thermal protection of the hot end components of gas turbines. Film cooling refers to the internal cooling airflow flowing out from the surface exposed to the high temperature environment through discrete holes and forming an air film to protect the hole outlet and its downstream area. At present, the most widely used hole type in film cooling technology is cylindrical hole. The cylindrical hole has a small outlet area, a small downstream lateral air film coverage area, a large cold air jet momentum, and is easily blown away from the wall under high blowing ratios. Due to the above limitations, cylindrical holes cannot meet the growing cooling needs caused by the improvement of gas turbine performance. It can be seen that the geometry of the film hole has a significant effect on the film cooling effect. Summary of the invention

[0004] In view of this, the present invention provides a discrete film cooling structure and a turbine blade combined with holes and slots, which are used to solve the technical problem that the existing film hole structure cannot meet the increasing cooling demand caused by the improvement of gas turbine performance.

[0005] A first aspect of an embodiment of the present invention provides a discrete air film cooling structure combining holes and slots, comprising: a plurality of cold air inlets, each cold air inlet comprising at least two discretely distributed air film holes, the aperture of the air film hole being smaller than the diameter of the cross-section of a standard cylindrical hole, the air film hole being used to allow cold air to enter; each air film hole being connected in sequence with a straight section cold air channel and an expansion section cold air channel; wherein, the expansion section cold air channels corresponding to the adjacent air film holes in each cold air inlet are connected in a plane through a connecting structure at a preset distance from the outlet end, forming a slot-type structure at the outlet end, and the expansion section cold air channel and the slot-type structure are used to expand the coverage width of the ejected cold air.

[0006] According to an embodiment of the present invention, the diameter of the air film hole is 0.4 to 0.7 times the diameter of the cold air inlet.

[0007] According to an embodiment of the present invention, each cold air inlet includes 2 to 6 air film holes.

[0008] According to an embodiment of the present invention, along the direction of cold air flow, the ratio between the length of the straight cold air channel and the total length of the discrete air film cooling structure combined with the holes and slots is 1 / 4 to 1 / 2.

[0009] According to an embodiment of the present invention, the expansion angles on both sides of the expansion section cold air channel are the same or different, and the values ​​of the expansion angles are all between 7° and 14°.

[0010] According to an embodiment of the present invention, along a direction perpendicular to the flow of cold air, the distance between two adjacent air film holes is 2 to 6 times the diameter of the air film hole.

[0011] According to an embodiment of the present invention, along the direction of cold air flow, the difference between the total length of the discrete air film cooling structure combined with holes and slots and the length of the connecting structure is greater than the length of the straight section of the cold air channel; the ratio of the length of the connecting structure to the total length of the discrete air film cooling structure combined with holes and slots is 1 / 4 to 1 / 3.

[0012] According to an embodiment of the present invention, the distance between two adjacent cold air inlets is 5 to 7 times the diameter of the cross section of a standard cylindrical hole.

[0013] According to an embodiment of the present invention, the angle between the flow direction of the cold air ejected from the groove structure and the cooled surface is 30° to 70°.

[0014] A second aspect of an embodiment of the present invention provides a turbine blade for a gas turbine, comprising the above-mentioned discrete air film cooling structure combined with holes and slots, wherein the discrete air film cooling structure combined with holes and slots is arranged on the pressure surface, suction surface and end wall of the turbine blade.

[0015] The discrete film cooling structure and turbine blade combined with holes and slots provided in the embodiments of the present invention can at least achieve the following technical effects:

[0016] Due to the film cooling structure, the standard cylindrical hole with a diameter of D is used as a reference, the aperture of the air film hole is reduced, the number of air film holes is increased, and multiple air film cooling holes with reduced aperture ratios are used to replace the original single air film cooling hole. The cold air inlet end is a discrete hole structure with two or more holes with a certain spacing, and the gas outlet end is a slot structure with a lateral width exceeding the hole spacing. Each discrete hole has a lateral expansion structure, and the expansion structure between two adjacent holes is connected by a plane at a certain distance from the outlet end, thereby forming a slot structure with a larger width at the outlet end. Therefore, compared with the traditional outlet expansion hole, the air film hole structure can significantly expand the outlet air film coverage width, and the increase in the outlet area reduces the outlet momentum of the cold air jet, which can better adhere to the wall surface and is not easy to blow away from the wall surface under high blowing ratios. The cooling outflow diffuses in the outlet slot structure before merging into the mainstream, increasing the lateral diffusion capacity of the coolant and forming a multi-peak air film at the outlet, which significantly improves the air film cooling effect without increasing the amount of cold air. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0018] Figure 1A The structure diagram of a conventional air film cooling structure based on fan-shaped holes is schematically shown.

[0019] Figure 1B The cross-sectional shape of the fan-shaped holes in the conventional air film cooling structure based on fan-shaped holes is schematically shown.

[0020] Figure 2A The structure diagram of a discrete air film cooling structure combined with holes and slots according to an embodiment of the present invention is schematically shown.

[0021] Figure 2B Schematically shows an embodiment of the present invention Figure 2A A view of the discrete air film cooling structure with a combination of holes and slots.

[0022] Figure 2C Schematically shows an embodiment of the present invention Figure 2B A B-direction view of the discrete air film cooling structure with a combination of holes and slots.

[0023] Figure 2D Schematically shows an embodiment of the present invention Figure 2B A C-direction view of the discrete film cooling structure with a combination of holes and slots.

[0024] Figure 3A A B-direction view of a discrete air film cooling structure combined with holes and slots according to another embodiment of the present invention is schematically shown.

[0025] Figure 3B A C-direction view of a discrete air film cooling structure combined with holes and slots according to another embodiment of the present invention is schematically shown.

[0026] Figure 4 A diagram schematically shows a comparison of the cooling effect of a discrete air film cooling structure combining holes and slots provided in an embodiment of the present invention and the cooling effect of a conventional film cooling structure based on fan-shaped holes.

[0027] Figure 5 A diagram schematically shows the lateral efficiency comparison at the downstream x / D=5 between the discrete air film cooling structure combining holes and slots provided in an embodiment of the present invention and the conventional film cooling structure based on fan-shaped holes.

[0028] Figure 6 A diagram schematically shows a comparison of the lateral average cooling effect of the discrete air film cooling structure combined with holes and slots provided in an embodiment of the present invention and the traditional film cooling structure based on fan-shaped holes.

[0029] Figure 7 The structure of a turbine blade for a gas turbine provided by an embodiment of the present invention is schematically shown.

[0030] Figure 8 A diagram schematically shows a comparison of the lateral average cooling effect distribution on the suction surface of a moving blade between a discrete air film cooling structure combining holes and slots provided in an embodiment of the present invention and a conventional film cooling structure based on fan-shaped holes. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. 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] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the description of the present invention, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the subsystem or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0035] 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 invention. The shapes, sizes, and positional relationships of the components in the drawings do not reflect the actual size, proportion, and actual positional relationship. In addition, in the present invention, any reference symbol between brackets should not be constructed as a limitation to the present invention.

[0036] Similarly, in order to simplify the present invention and help understand one or more of the various disclosed aspects, in the above description of exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. The description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0038] In order to solve the technical problem that the existing film hole structure cannot meet the growing cooling demand caused by the performance improvement of gas turbines, scholars have conducted a lot of research on the shape of film holes and proposed a variety of new film cooling hole structures. Among them, the outlet expansion hole has been put into practical use in gas turbines. As the outlet width of the expansion hole increases, the outlet area becomes larger, the momentum of the cold air jet outlet is weakened, the adhesion of the downstream air film is enhanced, and the film cooling effect is greatly improved.

[0039] Figure 1A The structure diagram of a conventional air film cooling structure based on fan-shaped holes is schematically shown.

[0040] Figure 1B The cross-sectional shape of the fan-shaped holes in the conventional air film cooling structure based on fan-shaped holes is schematically shown.

[0041] like Figure 1A and 1B As shown in the figure, the fan-shaped hole expands the rear half of the film hole laterally on the basis of the cylindrical hole. The fan-shaped hole can be divided into a straight section and an expansion section along the cold air 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 hole is consistent with that of the simple cylindrical hole, which is a circle with a diameter of D. The lateral expansion angle of the expansion section is γ. After expansion, the outlet width of the film hole increases, the outlet area becomes larger, the outlet momentum of the cold air jet decreases, and it is not easy to detach from the wall under high blowing ratios. Compared with the standard cylindrical hole, the fan-shaped hole structure enhances the flow of the cold air jet to both sides and increases the coverage area of ​​the cold air in the lateral direction. The outlet expansion structure of the film hole improves the film cooling effect to a certain extent and has been successfully applied on turbine blades. Although the increase in the outlet width of the film hole based on the film cooling structure of the fan-shaped hole is beneficial to the improvement of the film cooling effect, in order to avoid flow separation in the hole, the lateral expansion angle of the film hole should not be too large, that is, the increase in the outlet width of a single film hole is limited.

[0042] In the process of realizing the concept of the present invention, the applicant found that the continuous two-dimensional slot structure is the most ideal air film cooling structure, which can provide a continuous and uniform air film in the downstream and achieve a good cooling effect. However, the continuous slot structure cannot meet the strength requirements. Therefore, the present invention effectively combines the hole structure with the slot structure, uses a discrete hole row instead of a continuous two-dimensional slot, and proposes a high-performance air film cooling structure.

[0043] The discrete air film cooling structure combined with holes and slots provided in an embodiment of the present invention may include: multiple cold air inlets, each cold air inlet includes at least two discretely distributed air film holes, the aperture of the air film hole is smaller than the cross-section of a standard cylindrical hole, and the air film hole is used to let in cold air. Each air film hole is connected in sequence with a straight cold air channel and an expansion cold air channel. Among them, the expansion cold air channels corresponding to the adjacent air film holes in each cold air inlet are connected by a connecting structure plane at a preset distance from the outlet end, forming a slot-shaped structure at the outlet end, and the expansion cold air channel and the slot-shaped structure are used to expand the coverage width of the ejected cold air.

[0044] In an embodiment of the present invention, the sum of the cross-sectional areas of the air film cooling holes with the multiple aperture reduction ratios is ensured to be Figure 1A and Figure 1B Under the premise that the cross-sectional area of ​​the fan-shaped holes with a diameter of D shown in is equivalent, the higher the reduction degree of the aperture D1 of the air film hole, the more the number of air film holes N after the aperture reduction, and the larger the outlet width of the air film cooling structure of the present invention. Taking into account the limitations of processing accuracy and structural strength, the value of N should not be too large. The number of air film holes N in each cold air inlet is 2 to 6, which is specifically set according to the actual application scenario, and the present invention does not impose any restrictions. Several specific examples are listed below to explain in detail the discrete air film cooling structure combined with holes and slots provided in an embodiment of the present invention.

[0045] Figure 2A The structure diagram of a discrete air film cooling structure combined with holes and slots according to an embodiment of the present invention is schematically shown.

[0046] Figure 2B Schematically shows an embodiment of the present invention Figure 2A A view of the discrete air film cooling structure with a combination of holes and slots.

[0047] Figure 2C Schematically shows an embodiment of the present invention Figure 2B A B-direction view of the discrete air film cooling structure with a combination of holes and slots.

[0048] Figure 2D Schematically shows an embodiment of the present invention Figure 2B A C-direction view of the discrete film cooling structure with a combination of holes and slots.

[0049] like Figure 2A-2D As shown, the number N of air film holes in each cold air inlet of the discrete air film cooling structure combined with holes and slots provided in this embodiment is 2.

[0050] In the embodiment of the present invention, the cold air inlet is a standard cylindrical hole, and the diameter can be expressed as D. It should be noted that the standard cylindrical hole can be understood as Figure 1A and Figure 1BThe fan-shaped hole with a diameter of D is shown. The lateral distance between the two cold air inlets can be expressed as P, and the value of P can be 5D to 7D. Since the width of the outlet end of the air film cooling structure of the embodiment of the present invention is significantly larger than the standard cylindrical hole and the traditional expansion hole, the value of the lateral spacing P should not be too small. Taking the cylindrical aperture D as a reference, P is not less than 5D. Since the sum of the cross-sectional areas of the multiple aperture-scaled air film cooling holes of the air film cooling structure of the embodiment of the present invention is Figure 1A and Figure 1B The cross-sectional areas of the fan-shaped holes with a diameter of D shown in the figure are comparable, and the mass flow rates of the two are close. When the air film cooling structure of the present invention is applied to blade air film cooling, compared with using simple cylindrical holes and traditional fan-shaped holes, the large hole spacing P can reduce the number of cooling structures required along the blade height direction, which means that the amount of cold air used can be reduced.

[0051] In an embodiment of the present invention, the angle between the flow direction of the cold air ejected from the slot structure and the surface to be cooled is 30° to 70°. The angle between the flow direction of the cold air ejected from the slot structure and the surface to be cooled can also be called the injection angle, which can be represented by α, that is, the injection angle is the flow angle formed by the air film cooling structure and the surface to be cooled when it is used. Depending on the different positions where the cooling structure is used, the degree of α can be adjusted according to actual conditions, and the present invention does not impose any restrictions.

[0052] In the embodiment of the present invention, along the direction of cold air flow, the total length of the air film cooling hole structure combined with holes and slots along the direction of cold air flow can be represented by L, the length of the straight cold air channel can be represented by Lt, and the length of the connecting structure can be represented by Lh. The ratio Lt / L between the length Lt of the straight cold air channel and the total length L of the discrete air film cooling structure combined with holes and slots can be 1 / 4 to 1 / 2.

[0053] Furthermore, the expansion section of the cold air channel between two adjacent aperture reduction cold air inlets is penetrated by a plane at a certain distance from the outlet end, thereby forming a wide slot structure at the outlet end. Along the direction of cold air flow, the difference (L-Lh) between the total length L of the discrete air film cooling structure combined with the slot and the length Lh of the connection structure is greater than the length Lt of the straight section. The ratio Lh / L between the length Lh of the connection structure and the total length L of the discrete air film cooling structure combined with the slot and the hole can be 1 / 4 to 1 / 3, and this length also determines the depth of the slot structure at the outlet end. As Lh increases, the depth of the slot structure at the outlet end increases. The earlier the cold air enters the slot structure, the more fully the cold air diffuses in the slot structure.

[0054] Furthermore, the expansion angles on both sides of the expansion section cold air channel can be represented by γ1 and γ2, wherein the expansion angles on both outer sides are represented by γ1, and the expansion angles on the expansion side adjacent to the air film hole with the aperture reduction ratio are represented by γ2. γ1 and γ2 can be the same or different, and the values ​​of γ1 and γ2 can both be 7° to 14°. The outlet width of the air film cooling structure can be adjusted by adjusting the size of γ1 and γ2. The larger the lateral expansion angle, the larger the lateral width W of the outlet end slot structure, and the wider the lateral width covered by the air film.

[0055] Furthermore, the lateral spacing between multiple discrete film holes after aperture reduction can be represented by P1, and the diameter of the film hole can be represented by D1. The larger the lateral spacing P1, the farther the lateral spacing of the film cooling holes with aperture reduction, and the larger the width W of the slot structure at the outlet end after penetration. Considering that the cold air inlet end is a discrete structure, it takes a certain amount of time for the cold air to diffuse after flowing into the slot structure through the discrete inlet. If the value of P1 is too large, the cold air may not have enough time to fully diffuse before merging into the mainstream, resulting in uneven lateral distribution of the cold air. At the same time, if the length-to-width ratio of the slot structure at the outlet end is too large, it will affect the structural strength. It is recommended that the value of P1 should not be too large. Preferably, along the direction perpendicular to the flow of cold air, the distance P1 between two adjacent film holes is 2 to 6 times the diameter D1 of the film hole, and the diameter D1 of the film hole after aperture reduction is 0.4D-0.7D.

[0056] Figure 3A A B-direction view of a discrete air film cooling structure combined with holes and slots according to another embodiment of the present invention is schematically shown.

[0057] Figure 3B A C-direction view of a discrete air film cooling structure combined with holes and slots according to another embodiment of the present invention is schematically shown.

[0058] like Figure 3A and 3B As shown, Figure 2A-2D The difference of the discrete air film cooling structure with hole and slot combination shown is that the number N of air film holes in each cold air inlet of the discrete air film cooling structure with hole and slot combination is 3. Figure 2A-2D , I will not go into details here.

[0059] In order to further verify the advantages of the discrete air film cooling structure combined with holes and slots provided in the embodiment of the present invention, the embodiment of the present invention provides some simulation data for support.

[0060] Figure 4 A diagram schematically shows a comparison of the cooling effect of a discrete air film cooling structure combining holes and slots provided in an embodiment of the present invention and the cooling effect of a conventional film cooling structure based on fan-shaped holes.

[0061] like Figure 4 As shown, Figure 4 The upper part is a schematic diagram of the cooling effect of a conventional film cooling structure based on fan-shaped holes, and the lower part is a schematic diagram of the cooling effect of an air film cooling structure according to an embodiment of the present invention. In the figure, x represents the distance in the X-axis direction, y represents the distance in the Y-axis direction, and D is the cross-sectional diameter of the fan-shaped hole. Figure 4 The depth of the color in the figure represents the film cooling efficiency. The lighter the color, the lower the cooling efficiency, and the darker the color, the higher the cooling efficiency. By comparing the cooling efficiency distribution in the two figures, it can be seen that compared with the traditional fan-shaped holes, the film cooling structure greatly increases the lateral coverage area of ​​the downstream cold air and improves the cooling effect of the downstream area of ​​the film hole.

[0062] Figure 5 A diagram schematically shows the lateral efficiency comparison at the downstream x / D=5 between the discrete air film cooling structure combining holes and slots provided in an embodiment of the present invention and the conventional film cooling structure based on fan-shaped holes.

[0063] like Figure 5 As shown in the figure, by comparison, it is found that the lateral air film coverage width provided by the fan-shaped hole is smaller, and the double peak mode at the outlet of the fan-shaped hole gradually disappears during the flow process, and the double peak distribution is no longer obvious when it develops to x / D=5. The air film cooling hole of the present invention provides a wider lateral air film coverage, and is in the form of a multi-peak air film.

[0064] Figure 6 A diagram schematically shows a comparison of the lateral average cooling effect of the discrete air film cooling structure combined with holes and slots provided in an embodiment of the present invention and the traditional film cooling structure based on fan-shaped holes.

[0065] like Figure 6 As shown, the film cooling effect of the discrete film cooling structure hole pattern combined with holes and slots provided in the embodiment of the present invention is improved to a certain extent in the downstream, especially in the near downstream area, the cooling effect is significantly improved, and the overall improvement is about 37%.

[0066] It should be noted that Figure 5 , Figure 6The blowing ratio M of the flat model used in the test is 2.0, the mainstream speed is 50m / s, and the density of cold air to the mainstream is 1.5. The parameters of the air film cooling structure used are as follows: the diameter D of the traditional fan-shaped hole is 3mm, the total length L of the fan-shaped hole is 6D, the ratio of the straight section to the total length of the air film hole Lt / L is 1 / 3, and the expansion angle γ is 10°. In the air film cooling structure of the embodiment of the present invention, the number N of air film holes after aperture reduction is 3, the diameter D1 of each air film hole after aperture reduction is 0.58D, and the lateral spacing P1 of the air film holes after aperture reduction is 3D1. The total length L of each air film hole after aperture reduction is 6D, and the ratio Lt / L to the total length of the air film hole is 1 / 3; the length Lh of the continuous section at the outlet along the cold air flow direction is 1.5D, and the ratio Lh / L to the total length of the air film hole is 1 / 4. The expansion angles γ1 and γ2 of the expansion section of the cooling structure provided by the present invention are both 10°. The spray angle α of the film cooling structure based on the fan-shaped holes and the air film cooling structure provided by the embodiment of the present invention are both 30°.

[0067] Based on the same inventive concept, an embodiment of the present invention further provides a turbine blade for a gas turbine.

[0068] Figure 7 The structure of a turbine blade for a gas turbine provided by an embodiment of the present invention is schematically shown.

[0069] like Figure 7 As shown, the turbine blade for a gas turbine may include the above-described discrete air film cooling structure combined with holes and slots, wherein the discrete air film cooling structure combined with holes and slots is arranged on the pressure surface, suction surface and end wall of the turbine blade. The specific details are not repeated here.

[0070] Figure 8 A diagram schematically shows a comparison of the lateral average cooling effect distribution on the suction surface of a moving blade between a discrete air film cooling structure combining holes and slots provided in an embodiment of the present invention and a conventional film cooling structure based on fan-shaped holes.

[0071] like Figure 8 As shown, compared with the film cooling structure based on fan-shaped holes, the film cooling effect of the air film cooling structure provided by the embodiment of the present invention is improved by about 51% overall. This result is a numerical simulation result, the simulated fan-shaped hole diameter D = 1mm, and the expansion angle γ is 10°. The number of air film holes N after the aperture reduction is 3, the diameter D1 is 0.58mm, and the expansion angles γ1 and γ2 of the expansion section are both 10°.

[0072] In summary, an embodiment of the present invention provides a discrete film cooling structure combining holes and slots. Taking a simple cylindrical hole with a diameter of D as a reference, the total cross-sectional area of ​​the film holes is kept unchanged, the aperture of the film holes is reduced, the number of film holes is increased, and a single film cooling hole is replaced by a plurality of film cooling holes with reduced aperture ratios. At the same time, drawing on the continuous slot structure, the expansion structure of a plurality of discrete holes with conventional aperture reduction ratios is connected by a plane at a certain distance from the outlet end, thereby forming a large-width slot structure at the outlet end, which effectively expands the outlet width of the hole.

[0073] The above is only a specific embodiment of the present invention, but the protection scope of this application is not limited thereto. Any changes or substitutions made within the spirit and principle of the present invention should be included in the protection scope of this application. Therefore, the protection scope of this application should be based on the protection scope of the claims.

Claims

1. A discrete air film cooling structure combined with holes and slots, comprising: A plurality of cold air inlets, each of which comprises at least two discretely distributed air film holes, the aperture of the air film hole being smaller than the diameter of the cross section of a standard cylindrical hole, and the air film hole being used to allow cold air to enter; Each of the air film holes is sequentially connected to a straight cold air channel and an expansion cold air channel; Among them, the expansion section cold air channel corresponding to the adjacent air film holes in each cold air inlet is connected by a connecting structure plane at a preset distance from the outlet end, forming a groove structure at the outlet end, and the expansion section cold air channel and the groove structure are used to expand the coverage width of the ejected cold air.

2. The hole-slot combined discrete air film cooling structure according to claim 1, wherein: The diameter of the air film hole is 0.4 to 0.7 times the diameter of the cross section of the standard cylindrical hole.

3. The hole-slot combined discrete air film cooling structure according to claim 1 or 2, wherein: Each of the cold air inlets includes 2 to 6 air film holes.

4. The hole-slot combined discrete air film cooling structure according to claim 1, wherein: Along the direction of the cold air flow, the ratio between the length of the straight cold air channel and the total length of the discrete air film cooling structure combined with the holes and grooves is 1 / 4 to 1 / 2.

5. The hole-slot combined discrete air film cooling structure according to claim 4, wherein: The expansion angles on both sides of the expansion section cold air channel are the same or different, and the values ​​of the expansion angles are all between 7° and 14°.

6. The hole-slot combined discrete air film cooling structure according to claim 4 or 5, wherein: Along a direction perpendicular to the flow of the cold air, a distance between two adjacent air film holes is 2 to 6 times the diameter of the air film hole.

7. The hole-slot combined discrete air film cooling structure according to claim 1 or 4, wherein: Along the direction of the cold air flow, the difference between the total length of the discrete air film cooling structure combined with the holes and slots and the length of the connecting structure is greater than the length of the straight section of the cold air channel; the ratio of the length of the connecting structure to the total length of the discrete air film cooling structure combined with the holes and slots is 1 / 4 to 1 / 3.

8. The hole-slot combined discrete air film cooling structure according to claim 1, wherein: The distance between two adjacent cold air inlets is 5 to 7 times the diameter of the cross section of the standard cylindrical hole.

9. The hole-slot combined discrete air film cooling structure according to claim 1, wherein: The angle between the flow direction of the cold air ejected from the groove structure and the cooled surface is 30° to 70°.

10. A turbine blade for a gas turbine, comprising the discrete film cooling structure with hole and slot combination according to any one of claims 1 to 9, wherein: The hole-slot combined discrete air film cooling structure is arranged on the pressure surface, suction surface and end wall of the turbine blade.

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