Non-axisymmetric air film cooling structure and turbine blade

Abstract

The non-axisymmetric air film cooling structure comprises a plurality of air film holes, each air film hole comprises a cold air inlet, a straight section cold air channel, an expansion section cold air channel and a cold air outlet, one end of each straight section cold air channel communicates with the corresponding cold air inlet, and the other end of each straight section cold air channel communicates with one end of the corresponding expansion section cold air channel; the other end of the expansion section cold air channel is communicated with the cold air outlet; in the direction perpendicular to the flow direction of cold air, the cross section of the straight section cold air channel is composed of a runway shape and a semicircle located on the long side of the runway shape, and the central axis of the semicircle deviates from the middle point of the long side. In the direction perpendicular to the flow direction of the cold air, the cross section of the cold air channel of the expansion section is composed of a runway shape and a semicircle located on the long edge side of the runway shape, and arc edges on the two sides of the runway shape gradually expand towards the two sides of the flow direction of the cold air in the flow direction of the cold air.

Description

Technical Field

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

[0002] Gas turbines are widely used in the fields of ship propulsion, aerospace propulsion, industrial power generation, etc., and are an indispensable power device for a country's development. For gas turbines, increasing the turbine inlet temperature is an effective way to improve the performance of gas turbines, 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. The principle of film cooling is that the low-temperature gas from the compressor is transported to the internal cooling channel of the turbine blade through the air system, and is ejected through the discrete film cooling holes on the blade surface to form a layer of low-temperature air film on the surface, which can isolate the wall from the high-temperature mainstream and take away some heat, thereby effectively protecting the turbine blade.

[0004] 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 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 demand caused by the performance improvement of gas turbines. Based on this, a variety of new film cooling hole structures such as expansion holes, sister holes, double jet holes, and contraction slit holes have been proposed one after another. The new film cooling hole structure has improved the film cooling performance to a certain extent, but due to the complex structure, high processing difficulty, and high processing cost, only expansion holes have been practically applied in advanced gas turbine turbines. However, the cold air flow at the inlet of the existing expansion hole film cooling hole is not uniform, resulting in the cold air outflow to one side of the film hole deflecting, and the downstream film coverage is uneven, affecting the film cooling effect. The increase in the width of the film hole outlet expands the coverage of the cooling film in the span direction, and also makes the problem of film deflection more obvious. Summary of the invention

[0005] In view of this, the present invention provides a non-axisymmetric air film cooling structure and a turbine blade, which are used to solve the problem that the cold air flow at the inlet of the existing air film hole structure is uneven, resulting in the cold air outflow being deflected to one side of the air film hole, the downstream air film coverage is uneven, and the increase in the outlet width of the air film hole expands the coverage range of the cooling air film in the span direction, causing the air film to be deflected.

[0006] A first aspect of an embodiment of the present invention provides a non-axisymmetric air film cooling structure, comprising: a plurality of air film holes, each air film hole comprising a cold air inlet, a straight cold air channel, an expansion cold air channel and a cold air outlet, wherein one end of the straight cold air channel is connected to the cold air inlet, and the other end is connected to one end of the expansion cold air channel, and the other end of the expansion cold air channel is connected to the cold air outlet; along a direction perpendicular to the flow of the cold air, a cross-section of the straight cold air channel consists of a runway shape and a semicircular arc located on the long side of the runway shape, and a central axis of the semicircular arc deviates from the midpoint of the long side; along a direction perpendicular to the flow of the cold air, a cross-section of the expansion cold air channel consists of a runway shape and a semicircular arc located on the long side of the runway shape, and the arc edges on both sides of the runway shape gradually expand along the flow direction of the cold air toward both sides of the flow direction of the cold air.

[0007] According to an embodiment of the present invention, the semicircular arc of the expansion section cold air channel does not expand along the flow direction of the cold air or is divided into two sections at a center point and expands toward both sides.

[0008] According to an embodiment of the present invention, the semicircular arc of the expansion section cold air channel is divided into two sections at a center point and the angle range of expansion to both sides is 0° to 14°.

[0009] According to an embodiment of the present invention, the width of the runway shape in the cross section of the straight section of the cold air channel along the long side direction is 1.2 to 2 times the diameter of the cross section of the standard cylindrical hole; the ratio of the width of the runway shape in the cross section of the straight section of the cold air channel along the long side direction to the height in the direction perpendicular to the long side direction is 2 to 5; the radius of the semicircular arc in the cross section of the straight section of the cold air channel is half of the height of the runway shape in the direction perpendicular to the long side direction.

[0010] According to an embodiment of the present invention, the cross-sectional area of ​​the straight section cold air passage is equal to the cross-sectional area of ​​the standard cylindrical hole.

[0011] According to an embodiment of the present invention, the distance δ of the central axis of the semicircular arc from the midpoint of the long side satisfies the condition:

[0012]

[0013] Wherein, W is the width of the runway shape in the cross section of the straight section of the cold air passage along the long side direction, and R is the radius of the semicircular arc in the cross section of the straight section of the cold air passage.

[0014] According to an embodiment of the present invention, the total length of the air film holes is 2.8 to 8 times the diameter of the cross section of a standard cylindrical hole, and the hole spacing between two adjacent air film holes is 5 to 8 times the diameter of the cross section of the standard cylindrical hole.

[0015] According to an embodiment of the present invention, the ratio of the length of the straight section of the cold air channel to the total length of the air film holes is 1 / 4 to 1 / 2.

[0016] According to an embodiment of the present invention, the expansion angle of the expansion section cold air channel is 7° to 14°; the angle between the flow direction of the cold air blown out of the cold air outlet and the cooled surface is between 30° and 70°.

[0017] A first aspect of an embodiment of the present invention provides a turbine blade for a gas turbine, comprising the above-mentioned non-axisymmetric air film cooling structure, wherein the non-axisymmetric air film cooling structure is arranged on the pressure surface, suction surface and end wall of the turbine blade, and is used to cool the pressure surface, suction surface and end wall.

[0018] The non-axisymmetric film cooling structure and turbine blade provided in the embodiments of the present invention can at least achieve the following technical effects:

[0019] The non-axisymmetric air film cooling structure changes the traditional circular cross-section of the air film cooling hole into a runway-shaped cross-section with a lengthened side semicircular arc. Compared with the traditional circular cross-section, the runway-shaped cross-section increases the width of the air film hole, can obtain a wide air film coverage, and enhances the air film's wall-adhering ability under high blowing ratios. The semicircular arc expands the flow area at its location, allowing the low-speed cooling air to gather in the formed flow groove, while the high-speed cooling air is biased to both sides of the hole, so it is easy to form a double-peak air film, improve the phenomenon of the air film downstream of the hole being deflected to one side, improve the coverage of the downstream air film, and enhance the air film cooling effect. In addition, if the central axis of the semicircular arc in the cross-section deviates from the midpoint of the long side, the flow at the inlet of the air film hole can be adjusted to control the uniform distribution of the cold air in the air film hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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:

[0021] Figure 1A The three-dimensional structure diagram of a non-axisymmetric film cooling structure according to an embodiment of the present invention is schematically shown.

[0022] Figure 1B Schematically shows an embodiment of the present invention Figure 1A A cross-sectional view of the non-axisymmetric film cooling structure shown.

[0023] Figure 1C Schematically shows an embodiment of the present invention Figure 1A AA cross-sectional view of the straight section of the cooling air channel in the non-axisymmetric film cooling structure shown.

[0024] Figure 1D Schematically shows an embodiment of the present invention Figure 1A The lateral spacing between two adjacent air film holes in the non-axisymmetric air film cooling structure shown.

[0025] Figure 2A cross-sectional view of a non-axisymmetric film cooling structure according to another embodiment of the present invention is schematically shown.

[0026] Figure 3A A cross-sectional view of a non-axisymmetric film cooling structure according to yet another embodiment of the present invention is schematically shown.

[0027] Figure 3B Schematically shows an embodiment of the present invention Figure 3A AA cross-sectional view of the straight section of the cooling air channel in the non-axisymmetric film cooling structure shown.

[0028] Figure 4 The structure of a turbine blade for a gas turbine provided by an embodiment of the present invention is schematically shown.

[0029] Figure 5 The diagram schematically shows the application position of the non-axisymmetric film cooling structure provided by an embodiment of the present invention in a turbine blade cooling channel.

[0030] Figure 6 A diagram schematically shows a comparison between the effect of the non-axisymmetric film cooling structure provided by an embodiment of the present invention and the film cooling effect of a traditional fan-shaped hole.

[0031] Figure 7 A schematic diagram shows a comparison of the average lateral cooling effect distribution of the non-axisymmetric film cooling structure provided by an embodiment of the present invention and the traditional fan-shaped holes on the turbine power suction surface. DETAILED DESCRIPTION

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] In the process of realizing the concept of the present invention, the applicant found that the two-dimensional slit structure is an ideal form of air film hole, which can provide uniform and continuous air film protection for the cooled wall surface, but the two-dimensional slit structure seriously damages the strength of the turbine blade, so a discrete hole row is used instead. Inspired by the two-dimensional slit air film cooling structure, the traditional circular cross section is converted into a flattened cross section, and a certain angle is expanded in the span direction, which can further expand the cross-sectional width, thereby further improving the air film cooling performance. At the same time, the semicircular arc is lengthened on the side of the runway-shaped section, and the semicircular arc expands the flow area at its location, so that the low-speed cooling air gathers in the formed flow groove, and the high-speed cooling air deviates to both sides of the hole, so it is easy to form a double-peak air film, improve the phenomenon of the air film downstream of the hole deflecting to one side, improve the coverage of the downstream air film, and enhance the air film cooling effect. In addition, if the central axis of the semicircular arc in the cross section deviates from the midpoint of the long side, the flow condition at the inlet of the air film hole can be adjusted to control the uniform distribution of the cold air in the air film hole.

[0040] Based on this, an embodiment of the present invention provides a non-axisymmetric air film cooling structure, including: a plurality of air film holes, each air film hole includes a cold air inlet, a straight cold air channel, an expansion cold air channel and a cold air outlet, one end of the straight cold air channel is connected to the cold air inlet, and the other end is connected to one end of the expansion cold air channel, and the other end of the expansion cold air channel is connected to the cold air outlet. Along the direction perpendicular to the flow of the cold air, the cross-section of the straight cold air channel consists of a runway shape and a semicircular arc located on the long side of the runway shape. Along the direction perpendicular to the flow of the cold air, the cross-section of the expansion cold air channel consists of a runway shape and a semicircular arc located on the long side of the runway shape, and the arc edges on both sides of the runway shape gradually expand along the flow direction of the cold air to both sides of the flow direction of the cold air.

[0041] The non-axisymmetric air film cooling structure is described below with reference to specific embodiments.

[0042] Figure 1A The three-dimensional structure diagram of a non-axisymmetric film cooling structure according to an embodiment of the present invention is schematically shown.

[0043] Figure 1B Schematically shows an embodiment of the present invention Figure 1A A cross-sectional view of the non-axisymmetric film cooling structure shown.

[0044] Figure 1C Schematically shows an embodiment of the present invention Figure 1A AA cross-sectional view of the straight section of the cooling air channel in the non-axisymmetric film cooling structure shown.

[0045] like Figure 1A to Figure 1CAs shown, the non-axisymmetric air film cooling structure as a whole consists of a connected straight section cold air channel 1 and an expansion section cold air channel 2, wherein the straight section cold air channel 1 is located on the cold air side and is connected to the cold air inlet, and the expansion section cold air channel 2 is located on the gas side and is connected to the cold air outlet.

[0046] In the embodiment of the present invention, the cross section of the straight section cold air passage 1 is composed of a racetrack shape 3 and semicircular arcs 4 and 5 located on both sides of the racetrack shape 3. The cross section of the expansion section cold air passage 2 is formed by the semicircular arcs 4 and 5 on both sides of the racetrack shape 3 in the straight section cross section expanding at a certain angle in the lateral direction. The expansion angle γ of the expansion section cold air passage can be 7° to 14°.

[0047] As an optional implementation, the central axis of the semicircular arc coincides with the midpoint of the long side, and the axis is located at the center point of the racetrack shape when viewed from a direction perpendicular to the AA section ( Figure 1C and Figure 1B ), that is, the distance δ that the central axis of the semicircular arc deviates from the midpoint of the long side is 0.

[0048] In the embodiment of the present invention, assuming that the total length of the air film hole is L, the length of the straight cold air passage 1 is Lt, and the diameter of the cross section of the standard cylindrical hole is D, the total length L of the air film hole is 2.8 to 8 times the diameter D of the cross section of the standard cylindrical hole, and the ratio Lt / L of the length Lt of the straight cold air passage to the total length L of the air film hole is 1 / 4 to 1 / 2. It should be noted that the standard cylindrical hole can be understood as the cylindrical hole of the existing air film structure, and the geometric dimensions of the non-axisymmetric air film cooling structure of the embodiment of the present invention are all converted to the cylindrical hole diameter D, and a correlation can be established between the usual hole type and the non-circular cross-section hole for easy comparison.

[0049] In an embodiment of the present invention, the angle α between the flow direction of the cold air blown out of the cold air outlet and the cooled surface is between 30° and 70°. Depending on the position of the air film hole on the turbine blade, the flow angle α can take different values ​​according to needs.

[0050] Continue reading Figure 1C A semicircular arc 6 is added to the long side of the runway shape 3, and the cross-sectional area of ​​the straight section of the cold air passage formed by the runway shape 3 and the semicircular arc 6 is equal to the cross-sectional area of ​​the standard cylindrical hole.

[0051] Assuming that the width of the racetrack shape in the cross section of the straight section of the cold air passage along the long side direction is W, the height of the racetrack shape in the cross section of the straight section of the cold air passage along the direction perpendicular to the long side direction is H, and the radius of the semicircular arc 6 is R, then the width W of the racetrack shape in the cross section of the straight section of the cold air passage along the long side direction is 1.2 to 2 times the diameter D of the cross section of the standard cylindrical hole, and the ratio W / H of the width W of the racetrack shape in the cross section of the straight section of the cold air passage along the long side direction to the height H in the direction perpendicular to the long side direction is 2 to 5. The radius R of the semicircular arc in the cross section of the straight section of the cold air passage is half of the height H of the racetrack shape in the direction perpendicular to the long side direction.

[0052] Continue to see Figure 1B The semicircular arc 6 of the expansion section cold air channel 2 does not expand along the flow direction of the cold air, that is, the semicircular arc 6 maintains its shape along the flow direction of the cold air to the cold air outlet.

[0053] Figure 1D Schematically shows an embodiment of the present invention Figure 1A The lateral spacing between two adjacent air film holes in the non-axisymmetric air film cooling structure shown.

[0054] like Figure 1D As shown, the hole spacing between two adjacent air film holes is P, and the hole spacing P between two adjacent air film holes is 5 to 8 times the diameter D of the cross section of the standard cylindrical hole.

[0055] Figure 2 A cross-sectional view of a non-axisymmetric film cooling structure according to another embodiment of the present invention is schematically shown.

[0056] like Figure 2 The difference between the non-axisymmetric air film cooling structure shown in FIG1 is that the semicircular arc 6 of the expansion section cold air channel 2 is divided into two sections at the center point and expands to both sides. By expanding the semicircular arc 6, the shape of the air film hole outlet changes significantly. The angle γ1 of the expansion section cold air channel is divided into two sections at the center point and expands to both sides is 0° to 14°.

[0057] It should be noted that Figure 2 Other details of the non-axisymmetric air film cooling structure shown are the same as the non-axisymmetric air film cooling structure shown in FIG. 1 , and are not described again here.

[0058] Figure 3A A cross-sectional view of a non-axisymmetric film cooling structure according to yet another embodiment of the present invention is schematically shown.

[0059] Figure 3B Schematically shows an embodiment of the present invention Figure 3A AA cross-sectional view of the straight section of the cooling air channel in the non-axisymmetric film cooling structure shown.

[0060] like Figure 3Aand Figure 3B As shown, the difference from the non-axisymmetric film cooling structure shown in FIG1 is that the distance δ of the center axis of the semicircular arc 6 from the midpoint of the long side satisfies the condition:

[0061]

[0062] Wherein, W is the width of the runway shape in the cross section of the straight section of the cold air passage along the long side direction, and R is the radius of the semicircular arc in the cross section of the straight section of the cold air passage.

[0063] That is, the central axis of the semicircular arc structure 6 does not coincide with the central axis of the racetrack shape 3, and the offset distance δ between the two does not exceed W / 2-R.

[0064] Figure 4 The structure of a turbine blade for a gas turbine provided by an embodiment of the present invention is schematically shown.

[0065] like Figure 4 As shown, the turbine blade for a gas turbine may include the non-axisymmetric air film cooling structure described above, wherein the non-axisymmetric air film cooling structure is provided on the pressure surface, suction surface and end wall of the turbine blade for cooling the pressure surface, suction surface and end wall. The specific details are not repeated here.

[0066] It should be noted that the flow conditions at the entrance of the film hole on the actual turbine blade are relatively complicated. The cooling channel inside the blade makes the cold air have a certain lateral velocity before entering the film hole, and the fin structure inside the channel makes the flow conditions near the film entrance more complicated. Under the influence of the cross flow in the cold channel inside the blade, the cold air deviates to one side when entering the entrance of the film hole, and the flow distribution in the hole is uneven. Through further expansion flow in the hole, the cold air outflow downstream of the hole is significantly deflected. The higher the blowing ratio, the greater the cold air velocity at the cold air inlet, the more obvious the deflection of the cold air to one side of the hole, and the greater the adverse effect on the film cooling effect. The non-axisymmetric film cooling structure of the embodiment of the present invention can change the position of the semicircular arc 6 on the long side according to the deflection of the film, and then adjust the distribution of the cold air in the hole. The semicircular arc 6 on the long side runs from the entrance of the cooling hole to the outlet of the cold air port, and the shapes of the entrance and outlet are changed accordingly. The semicircular structure on the long side expands the flow area at its location, so that the low-speed cooling air gathers in the flow groove formed, and the high-speed cooling air deviates to the two sides of the hole. Therefore, it is easy to form a double-peak air film, improve the deflection phenomenon of the air film downstream of the hole shifting to one side, and enhance the air film cooling effect.

[0067] Figure 5 The diagram schematically shows the application position of the non-axisymmetric film cooling structure provided by an embodiment of the present invention in a turbine blade cooling channel.

[0068] like Figure 5 As shown, there is a ribbed cooling channel structure 7 inside the turbine blade. Film holes 8 are provided on one side of the suction surface of the cooling channel 7, and the film holes 8 are film cooling holes in the embodiment of the present invention. According to the actual cooling requirements and the strength requirements of the blade, the non-axisymmetric film cooling structure of the embodiment of the present invention can be used at any position of the turbine blade.

[0069] In order to further illustrate the advantages of the non-axisymmetric air film cooling structure provided by the embodiment of the present invention, the following data are given below to prove it.

[0070] Figure 6 A diagram schematically shows a comparison between the effect of the non-axisymmetric film cooling structure provided by an embodiment of the present invention and the film cooling effect of a traditional fan-shaped hole.

[0071] like Figure 6 As shown, the upper part of the picture is a schematic diagram of the cooling effect of the non-axisymmetric air film cooling structure of the present invention, and the lower part is a schematic diagram of the cooling effect of the fan-shaped holes. Figure 6 The depth of the color represents the air 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 effects of the two holes, it can be seen that the cold air outflow downstream of the fan-shaped hole is deflected to one side, especially the closer to the cooling hole outlet, the more obvious the deflection. The high cooling efficiency area close to the fan-shaped hole outlet is obviously biased to one side of the air film hole. The cooling peak of the air film cooling hole of the present invention is roughly in the center position and is symmetrically distributed on both sides of the central axis of the air film hole, which improves the situation of the skewed air film coverage downstream of the air film hole, and the air film coverage area in the extension direction is increased, and the attenuation of the cooling efficiency along the flow direction is also greatly reduced.

[0072] Figure 7 A schematic diagram shows a comparison of the average lateral cooling effect distribution of the non-axisymmetric film cooling structure provided by an embodiment of the present invention and the traditional fan-shaped holes on the turbine power suction surface.

[0073] like Figure 7 As shown, the non-axisymmetric air film cooling structure implemented by the present invention has a certain degree of improvement in the air film cooling effect near downstream and far downstream, which is improved by about 15% overall. The above results show that the non-axisymmetric air film cooling structure implemented by the present invention has advantages in improving the cooling effect. By optimizing the hole parameters, the non-axisymmetric air film cooling structure implemented by the present invention can further obtain a high cooling effect, such as: changing the aspect ratio W / H in the cross section, moving the position of the semicircular arc structure, expanding the semicircular arc structure, etc.

[0074] Figure 6 and Figure 7The air film hole structure parameters used in the test are as follows: the width W of the straight section cross section of the air film hole is 1.4mm; the height H of the straight section cross section of the air film hole is 0.53mm; the radius of the semicircular arc structure on the long side of the straight section cross section of the air film hole is 0.265mm; the offset distance δ between the central axis of the semicircular arc and the midpoint of the long side of the runway shape is 0mm; the expansion angle of the expansion section of the air film hole is 7°; the total radial length of the air film hole is 6mm; the length of the straight section of the air film hole is 2mm.

[0075] To sum up, the non-axisymmetric air film cooling structure provided in the embodiment of the present invention can improve the distribution of cold air in the air film cooling holes, evenly distribute the cold air outflow at the outlet of the air film cooling holes, improve the deflection downstream of the air film holes, and can still provide a good air film coverage effect when the cold air flow is uneven.

[0076] 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 non-axisymmetric film cooling structure, comprising: A plurality of air film holes, each of which comprises a cold air inlet, a straight cold air channel, an expansion cold air channel and a cold air outlet, one end of the straight cold air channel is connected to the cold air inlet, the other end of the straight cold air channel is connected to one end of the expansion cold air channel, and the other end of the expansion cold air channel is connected to the cold air outlet; In a direction perpendicular to the flow of the cold air, the cross section of the straight cold air passage consists of a runway shape and a semicircular arc located on the long side of the runway shape; Along the direction perpendicular to the flow of cold air, the cross-section of the cold air channel in the expansion section consists of a runway shape and a semicircular arc located on the long side of the runway shape, and the arc edges on both sides of the runway shape gradually expand along the flow direction of the cold air to both sides of the flow direction of the cold air.

2. The non-axisymmetric film cooling structure according to claim 1, wherein: The semicircular arc of the expansion section cold air channel does not expand along the flow direction of the cold air or is divided into two sections at a center point and expands toward both sides.

3. The non-axisymmetric air film cooling structure according to claim 2, wherein: The semicircular arc of the expansion section cold air channel is divided into two sections at the center point and the angle range of expansion to both sides is 0° to 14°.

4. The non-axisymmetric film cooling structure according to claim 1, wherein: The width of the racetrack shape in the cross section of the straight cold air passage along the long side direction is 1.2 to 2 times the diameter of the cross section of the standard cylindrical hole; The ratio of the width of the runway shape in the cross section of the straight cold air passage along the long side to the height in the direction perpendicular to the long side is 2 to 5; The radius of the semicircular arc in the cross section of the straight section cold air passage is half of the height of the racetrack along the direction perpendicular to the long side.

5. The non-axisymmetric air film cooling structure according to claim 1 or 4, wherein: The cross-sectional area of ​​the straight cold air passage is equal to the cross-sectional area of ​​the standard cylindrical hole.

6. The non-axisymmetric air film cooling structure according to claim 1, wherein: The center axis of the semicircular arc deviates from the midpoint of the long side, and the distance δ of the center axis of the semicircular arc deviating from the midpoint of the long side satisfies the condition: Wherein, W is the width of the runway shape in the cross section of the straight section of the cold air channel along the long side direction, and R is the radius of the semicircular arc in the cross section of the straight section of the cold air channel.

7. According to the non-axisymmetric air film cooling structure of claim 1, the total length of the air film holes is 2.8 to 8 times the diameter of the cross section of a standard cylindrical hole, and the hole spacing between two adjacent air film holes is 5 to 8 times the diameter of the cross section of the standard cylindrical hole.

8. The non-axisymmetric air film cooling structure according to claim 1 or 7, wherein: The ratio of the length of the straight cold air channel to the total length of the air film holes is 1 / 4 to 1 / 2.

9. The non-axisymmetric film cooling structure according to claim 1, wherein: The expansion angle of the expansion section cold air channel is 7° to 14°; the angle between the flow direction of the cold air blown out of the cold air outlet and the cooled surface is between 30° and 70°.

10. A turbine blade for a gas turbine, comprising the non-axisymmetric film cooling structure according to any one of claims 1 to 9, wherein: The non-axisymmetric air film cooling structure is arranged on the pressure surface, suction surface and end wall of the turbine blade, and is used to cool the pressure surface, suction surface and end wall.

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