Gas turbine stator blade structure

Abstract

The present application discloses a gas turbine stator blade structure, comprising: a blade having a hollow cavity extending therethrough, an end plate connected to the end of the blade, the end plate comprising an end wall close to the blade and an outer surface opposite to the end wall; and an impingement cooling plate, the impingement cooling plate being in the shape of a free-form surface, a plurality of impingement cooling holes being provided on the impingement cooling plate, the impingement cooling plate being fixed to the outer surface of the end plate and forming a closed cooling cavity with the end plate, the hydraulic diameter of the impingement cooling hole being d, the vertical distance between the center point of the impingement cooling hole close to one end of the end plate and the end plate being z, and the ratio of d to z being between 1:8 and 1:1. The present application improves the impingement cooling efficiency of the impingement cooling hole, thereby improving the cooling and heat exchange efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of gas turbines, and in particular to a gas turbine stator blade structure. Background Art

[0002] With the development of science and technology and the demand for energy conservation and emission reduction, the inlet temperature of gas turbine blades continues to increase, and the inlet temperature has far exceeded the melting point of the blade material. Therefore, the hot end components inside the gas turbine generally adopt impingement cooling.

[0003] Existing gas turbines generally have impingement cooling plates on the blade end plates, and impingement cooling holes are opened in the impingement cooling plates. Cold air passes through the impingement cooling holes to cool the blade end plates and stators.

[0004] However, in related art, the impact distance from the impingement cooling plate to the blade end plate is fixed. After the cold air impacts, a cold air crossflow is formed, with the impact direction perpendicular to the flow direction. The cold air crossflow rate varies at different locations on the blade. When the impact distance is fixed for different areas of the impingement cooling plate, the crossflow rate of the cold air formed by the impingement increases along the flow direction, increasing the crossflow rate. This reduces the impact cooling effect of the impact cooling holes downstream of the cold air crossflow, resulting in suboptimal impact cooling efficiency at the impact cooling holes. Summary of the Invention

[0005] In order to improve the impingement cooling efficiency of the impingement cooling holes, the present application provides a gas turbine stator blade structure.

[0006] The present application provides a gas turbine stator blade structure adopting the following technical solution: comprising: a blade having a hollow cavity extending therethrough, an end plate connected to an end of the blade, the end plate comprising an end wall adjacent to the blade and an outer surface opposite to the end wall;

[0007] and an impingement cooling plate, wherein the impingement cooling plate is in a free-form surface shape and is provided with a plurality of impingement cooling holes. The impingement cooling plate is fixed to the outer surface of the end plate and forms a closed cooling cavity with the end plate. The hydraulic diameter of the impingement cooling hole is d, and the vertical distance between the center point of the impingement cooling hole close to one end of the end plate and the end plate is z, and the ratio of d to z is between 1:8 and 1:1.

[0008] By adopting the above technical solution, the hydraulic diameter d of each impingement cooling hole corresponds to the optimal impingement distance z. Different impingement distances form an impingement cooling plate with a free-form surface shape. When cold air impinges on the impingement cooling plate, the heat exchange efficiency of the impingement cooling can be improved.

[0009] Optionally, the impingement cooling hole is circular, elliptical or polygonal in shape.

[0010] By adopting the above technical solution, the hydraulic diameters of the impingement cooling holes of different shapes or different cross-sectional areas are different, resulting in corresponding different impingement cooling efficiencies. The heat exchange efficiency can be improved by selecting a reasonable hydraulic diameter and impingement distance of the impingement cooling holes.

[0011] Optionally, the impingement cooling hole includes an air inlet end and an air outlet end, the air inlet end is located on the side of the impingement cooling plate away from the end plate, and the air outlet end is located on the side of the impingement cooling plate close to the end plate, and the aperture of the air inlet end is greater than or equal to the aperture of the air outlet end.

[0012] By adopting the above technical solution, when the cold air flows to the surface of the impact cooling plate, since the aperture of the air inlet end is larger than the aperture of the air outlet end, the cold air pressure increases, the cold air flow rate increases, and the cold air heat exchange efficiency is improved.

[0013] Optionally, the end plate is provided with a first ventilation hole penetrating the hollow cavity, and the impingement cooling plate is provided with a second ventilation hole at a corresponding position in the hollow cavity, and the hydraulic diameter of the ventilation hole is larger than the hydraulic diameter of the impingement cooling hole.

[0014] By adopting the above technical solution, when cold air impacts the cooling plate, the cold air first passes through the second vent hole and then enters the cooling cavity. The cold air in the cooling cavity enters the hollow cavity from the first vent hole and cools the inner wall of the hollow cavity.

[0015] Optionally, the position of the impingement cooling plate corresponding to the end wall is the first opening area, and the position corresponding to the hollow cavity is the second opening area; the distribution density of the impingement cooling holes in the first opening area is greater than the distribution density in the second opening area.

[0016] By adopting the above technical solution, since the hollow cavity is cooled, the heat load of the end wall area other than the hollow cavity is relatively large, and the distribution density of the impingement cooling holes in this area is increased to improve the cooling effect on the end wall.

[0017] Optionally, the blade includes a leading edge stagnation point and a trailing edge, the convex area between the leading edge stagnation point and the trailing edge is defined as a suction surface, and the concave area between the leading edge stagnation point and the trailing edge is defined as a pressure surface. The blade also includes a blade leading edge, a suction surface gill area, and a pressure surface gill area. The distribution density of the impingement cooling holes at the corresponding positions of the suction surface gill area and the trailing edge is greater than the distribution density at the corresponding positions of the leading edge of the blade.

[0018] By adopting the above technical solution, the air film leaking from the end wall is difficult to cover the suction surface gill area and the trailing edge, and the heat is concentrated in the suction surface gill area and the trailing edge area. The corresponding impact cooling holes in this area are arranged more densely, thereby improving the cooling heat exchange efficiency of the end plate corresponding to this area.

[0019] Optionally, the concave area between the pressure surface gill area and the trailing edge is a throat area, and the distribution density of the impingement cooling holes at corresponding positions in the throat area is greater than the distribution density at corresponding positions on the leading edge of the blade.

[0020] By adopting the above technical solution, the high-temperature and high-pressure gas flow begins to accelerate from the leading edge of the blade and turns into turbulent flow in the throat area. The heat transfer coefficient of the high-temperature gas is strong, so the heat is concentrated in the throat area, which leads to an increase in the heat load at the position corresponding to the throat area of ​​the end plate. Therefore, it is necessary to increase the distribution density of the impingement cooling holes corresponding to this area.

[0021] Optionally, there are two end plates, which are located at opposite ends of the blade, and an impingement cooling plate is provided on the outer surface of each end plate.

[0022] By adopting the above technical solution, cold air impacts the impact cooling plates at both ends of the blade. Since each impact cooling hole at both ends of the blade has an optimal impact cooling distance, the cold air is gathered in the hollow cavity from the top and bottom of the hollow cavity respectively to achieve the optimal impact cooling heat exchange efficiency for the blade.

[0023] Optionally, the outer surface of the end plate is recessed toward the end wall to form a groove, and the cooling cavity is formed by the impact cooling plate and the bottom wall of the groove.

[0024] By adopting the above technical solution, a cooling cavity is formed by the impact cooling plate and the bottom surface of the groove. When the cold air passes through the impact cooling hole, it is gathered in the cooling cavity to cool the end plate, reduce the temperature of the end plate, and then flows into the hollow cavity through the vent hole to cool the blade.

[0025] Optionally, a plurality of end wall air film holes are provided in the area between the blades and in the area corresponding to the end plate.

[0026] By adopting the above technical solution, the cold air in the cooling cavity flows out from the air film holes of the end wall, meets the high-temperature and high-pressure combustion gas, and forms an air film on the end wall to cool and protect the end wall.

[0027] In summary, this application has at least one of the following beneficial effects:

[0028] 1. The surface of the impingement cooling plate is a free-form surface, so the distance between the impingement cooling hole and the end plate is not fixed. In areas with large cross-flow of cold air, the impingement distance is increased to reduce the cross-flow velocity of cold air, thereby improving heat exchange efficiency.

[0029] 2. In areas with high heat loads, the impingement cooling holes on the impingement cooling plate are densely distributed, increasing the amount of cold air fed and enhancing heat exchange efficiency. In areas with low heat loads, the impingement cooling holes are sparsely distributed. The impingement cooling capacity is adjusted accordingly based on the heat load distribution in different areas, making the temperature of the entire end wall more uniform and reducing the impact of thermal stress on the structure.

[0030] 3. The ratio of the hydraulic diameter of each impingement cooling hole to its impingement distance is between 1:8 and 1:1. The optimal ratio is then determined through simulation tests to improve the impingement cooling heat transfer efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application;

[0032] Figure 2 This is a schematic diagram of the exploded structure of an embodiment of the present application;

[0033] Figure 3 This is a schematic diagram of an embodiment of the present application in which an end plate on one side of a blade is removed;

[0034] Figure 4 This is a schematic diagram of the geometric area division of the outer surface of the blade in an embodiment of the present application;

[0035] Figure 5 It is a schematic cross-sectional view of an embodiment of the present application;

[0036] Figure 6 yes Figure 5 A magnified schematic diagram of part A;

[0037] Figure 7 is a partial schematic diagram of the impingement cooling plate;

[0038] Figure 8 It is a schematic diagram of the relationship between z / d and htc in the embodiment of the present application.

[0039] Explanation of the accompanying reference numerals: 1. blade; 11. hollow cavity; 12. blade leading edge; 121. leading edge stagnation point; 122. leading edge film hole; 13. trailing edge; 131. trailing edge film hole; 14. suction side; 15. pressure side; 16. suction side gill area; 17. pressure side gill area; 18. throat area; 19. blade body; 2. end plate; 21. end wall; 22. cooling cavity; 23. end wall film hole; 24. groove; 25. first ventilation hole; 3. impingement cooling plate; 31. first opening area; 32. second opening area; 33. impingement cooling hole; 331. air inlet end; 332. air outlet end; 34. second ventilation hole. DETAILED DESCRIPTION

[0040] The following is combined with Figure 1-8 This application is described in further detail.

[0041] An embodiment of the present application discloses a gas turbine stator blade structure.

[0042] refer to Figure 1 The gas turbine stator blade structure of the embodiment of the present application includes: two blades 1 and two end plates 2. A hollow cavity 11 is provided inside the blade 1. Both blades 1 are located between the two end plates 2, and the ends of the blades 1 are fixed to the end plates 2. Each end plate 2 is provided with an impingement cooling plate 3 on the end facing away from the blade 1. The impingement cooling plate 3 is a thin plate, generally 1-2 mm thick. The impingement cooling plate 3 and the end plate 2 can be connected by welding or other methods to achieve a fixed connection.

[0043] refer to Figure 2 The end plate 2 includes an end wall 21 proximal to the blade 1 and an outer surface opposite the end wall 21. The location of the impingement cooling plate 3 corresponding to the end wall 21 is a first opening area 31, and the location of the impingement cooling plate 3 corresponding to the hollow cavity 11 is a second opening area 32. In this embodiment, the first opening area 31 is provided with impingement cooling holes 33, while the second opening area 32 is not provided with impingement cooling holes 33. The shape of the impingement cooling holes 33 can be set to be circular, elliptical, or polygonal. In other embodiments, the second opening area 32 can also be provided with impingement cooling holes 33, and the distribution density of the impingement cooling holes 33 in the first opening area 31 is greater than the distribution density of the impingement cooling holes 33 in the second opening area 32, so as to improve the cooling efficiency at the location on the end plate 2 corresponding to the first opening area 31.

[0044] refer to Figure 2 The outer surface of the end plate 2 is recessed toward the end wall 21 to form a groove 24. The side of the groove 24 closest to the blade 1 forms a bottom wall. The bottom wall of the groove 24 is separated from the impingement cooling plate 3 to form a cooling cavity 22. Cooling gas enters the cooling cavity 22 through the impingement cooling holes 33, thereby cooling the end plate 2. The end plate 2 is provided with a first vent hole 25 that extends through the hollow cavity 11. The impingement cooling plate 3 is provided with a second vent hole 34 at a corresponding position in the hollow cavity 11. The aperture of the first vent hole 25 is greater than or equal to the aperture of the second vent hole 34. The apertures of both the first vent hole 25 and the second vent hole 34 are greater than the aperture of the impingement cooling hole 33.

[0045] Several end wall film holes 23 are provided on the bottom wall of the groove 24, corresponding to the area between the two blades 1. A portion of the cold air collected in the cooling chamber 22 enters the hollow cavity 11 through the first vent holes 25 to cool the inner wall of the hollow cavity 11. Another portion of the cold air flows out of the end wall film holes 23 and meets the high-temperature, high-pressure gas exhausted from the gas turbine combustion chamber, forming a cooling film on the end wall 21. This reduces direct contact between the gas and the end wall 21, thus achieving impingement cooling and film cooling to cool and protect the end wall 21.

[0046] refer to Figure 3 and Figure 4 The outer surface of the blade 1 includes a leading edge 12 and a trailing edge 13. A leading edge stagnation point 121 is provided at the leading edge 12. The convex area between the leading edge stagnation point 121 and the trailing edge 13 is defined as the suction surface 14, and the concave area between the leading edge stagnation point 121 and the trailing edge 13 is defined as the pressure surface 15. Gill areas are provided on both sides of the leading edge 12. The gill area on the suction surface 14 is the suction surface gill area 16, and the gill area on the pressure surface 15 is the pressure surface gill area 17.

[0047] Leading edge film holes 122 are provided at the leading edge 12 of the blade. The sidewall of the blade 1 forms the airfoil 19. These holes penetrate the airfoil 19 and connect the hollow cavity 11 with the exterior of the blade 1. Therefore, the cooling gas within the hollow cavity 11 is discharged through the leading edge film holes 122 to the exterior of the blade 1. At this point, the high-temperature, high-pressure gas exhausted from the gas turbine combustion chamber acts on the airfoil 19. When this gas meets the cooling gas, a film of air forms on the surface of the airfoil 19, effectively protecting it.

[0048] refer to Figure 2 and Figure 4 A gap exists between the end plate 2 and the combustion chamber transition section, allowing some cooling air to enter through the gap, forming a leakage film at the leading edge of the end wall 21. The areas of the end wall 21 corresponding to the suction gill area 16 and the trailing edge 13 are relatively far from the leading edge of the end wall 21, making it difficult for the leakage film to fully cover these areas. This results in a higher heat load at the areas of the end wall 21 corresponding to the suction gill area 16 and the trailing edge 13. On the impingement cooling plate 3, the distribution density of impingement cooling holes 33 is high in the areas corresponding to the suction gill area 16 and the trailing edge 13, allowing the cooling air to fully act on these areas, cooling the end wall 21 there, thereby reducing the heat load on the end wall 21 and protecting the end plate 2. The suction gill area 16 of the blade airfoil 19 is provided with suction film holes, and the trailing edge film holes 131 are provided in the trailing edge 13 area. Both of these holes form film cooling to reduce the heat load on the blade airfoil 19.

[0049] refer to Figure 3 and Figure 4The concave area between the pressure-side gill area 17 and the trailing edge 13 is the throat area 18. In addition to the high heat load intensity in the suction-side gill area 16 and trailing edge 13, the throat area 18 between the two blades 1 also experiences a high heat load intensity. This is because the high-temperature, high-pressure gas generated in the gas turbine combustion chamber flows through the throat area 18. The high-temperature gas accelerates at the blade leading edge 12, transitioning from laminar flow to turbulent flow. The flow becomes turbulent in the roaring area, increasing the flow velocity and enhancing the heat transfer coefficient of the high-temperature gas. Consequently, a large amount of heat is concentrated in the throat area 18. Therefore, to rapidly cool the blade airfoil 19 and endplate 2 in the throat area 18, impingement cooling holes 33 are also provided in the impingement cooling plate 3 at locations corresponding to the throat area 18. The distribution density of the impingement cooling holes 33 is relatively high here. In other areas with lower heat loads, the impingement cooling holes 33 are more sparsely distributed, reducing the cooling and heat transfer efficiency in these areas and alleviating the impact of local thermal stress on the structure.

[0050] refer to Figure 5 and Figure 6 The end of the impingement cooling hole 33 facing away from the end plate 2 is the air inlet end 331, and the end facing the end plate 2 is the air outlet end 332. In this embodiment of the present application, the aperture of the air inlet end 331 is larger than the aperture of the air outlet end 332. To improve the cooling effect on the blade 1 and the end plate 2, the diameters of the impingement cooling holes 33 at different locations are different.

[0051] In the embodiment of the present application, since the area between the first cheek area and the trailing edge 13 requires a higher cooling intensity, the impingement cooling holes 33 corresponding to this area have a smaller diameter but are distributed more densely, which can not only increase the air intake volume but also ensure a higher air flow velocity, thereby ensuring a better cooling effect.

[0052] refer to Figure 6 The vertical distance between the center point of the impact cooling hole 33 close to one end of the end plate 2 and the end plate 2 is the impact distance. In order to further improve the cooling effect, the impact distances corresponding to the impact cooling holes 33 at different positions are also different, resulting in different distances between different positions of the impact cooling plate 3 and the end plate 2. Therefore, the surface of the impact plate will be curved.

[0053] refer to Figure 6 and Figure 7 The characteristic length of the cross-sectional area of ​​the impingement cooling hole 33 is called the hydraulic diameter. For a circular impingement hole, its diameter is the hydraulic diameter. The hydraulic diameter of the impingement cooling hole 33 is four times the ratio of the flow cross-sectional area to the circumference. The hydraulic diameter of the impingement cooling hole 33 is d, and the impingement distance of the impingement cooling hole 33 is z. The corresponding Nusselt number Nu is calculated using the formula: Where Nu is the Nusselt number, Pr is the Prandtl number, Re is the Reynolds number, and x n is the distance between adjacent impingement cooling holes 33 in the X direction, yn is the distance between adjacent impingement cooling holes 33 in the y direction, x n / d and y n The ratio of / d ranges from 1 to 15.

[0054] refer to Figure 8 The larger Nu is, the stronger the heat transfer capacity is, and the better the cooling effect of the impingement cooling hole 33 on the end plate 2 is. The best impingement cooling effect is verified by simulation test, and the Nusselt number Nu is converted into the fluid heat transfer coefficient htc, which is in units of In this embodiment, an E-class gas turbine is selected, the hydraulic diameter d is in the range of 1-8 mm, the impingement distance z is in the range of 8-64 mm, and the ratio of d to z is between 1:8 and 1:1. A portion of the impingement cooling holes 33 located at the leading edge 12 of the blade is selected for testing. The test data are as follows:

[0055]

[0056] Impingement cooling efficiency is related to the hydraulic diameter, impingement distance, and arrangement and density of the impingement cooling holes 33. According to impingement cooling calculations, different hydraulic diameters correspond to optimal impingement distances. Impingement distances that are too large or too small will reduce the impingement cooling effect. Different optimal impingement distances shape the curved surface of the impingement plate. The free-form impingement plate maximizes impingement cooling for each impingement cooling hole 33, improving the overall impingement cooling effect.

[0057] In summary, the specific design steps of the free-form surface impingement cooling plate 3 proposed in this application are:

[0058] S1: Determine the arrangement, density, and hydraulic diameter of the impingement cooling holes 33 based on the heat load distribution of the end plate 2. In this embodiment, the impingement cooling holes 33 are densely arranged in areas with high heat loads, such as the throat area 18, the trailing edge 13, and the suction side cheek area 16. S2: Calculate the Nusselt number Nu for different impingement cooling distances. The optimal impingement distance is the impingement distance corresponding to the maximum Nusselt number Nu for each impingement cooling hole 33.

[0059] S3: selecting the distance between each impingement cooling hole 33 and the corresponding position of the end plate 2 according to the optimal impingement distance;

[0060] S4: Different impact distances form a free-form surface shape of the impact cooling plate 3 .

[0061] In other embodiments, other cooling methods may also be provided in the blade 1, such as bushing impingement cooling or convection cooling such as straight holes or serpentine channels, or a combination of cooling methods.

[0062] The implementation principle of a gas turbine stator blade in an embodiment of the present application is: by determining the hydraulic diameter, impact distance and distribution density of each impact cooling hole 33, the curved surface structure of the impact cooling plate 3 is obtained, so that the impact efficiency of each impact cooling hole 33 is optimized, thereby improving the overall impact cooling effect of the impact cooling plate 3.

[0063] The embodiments of this specific implementation method are all preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A gas turbine stator blade structure, characterized in that: include: A blade (1), wherein the blade (1) has a hollow cavity (11) extending therethrough, an end plate (2) is connected to an end portion of the blade (1), and the end plate (2) comprises an end wall (21) adjacent to the blade (1) and an outer surface opposite to the end wall (21); and an impact cooling plate (3), wherein the impact cooling plate (3) is in a free-form shape, a plurality of impact cooling holes (33) are provided on the impact cooling plate (3), the impact cooling plate (3) is fixed to the outer surface of the end plate (2) and forms a closed cooling cavity (22) between the impact cooling plate (3) and the end plate (2), the hydraulic diameter of the impact cooling hole (33) is d, the vertical distance between the center point of the impact cooling hole (33) on the side close to the end plate (2) and the end plate (2) is z, and the ratio of d to z is between 1:8 and 1:

1.

2. A gas turbine stator blade structure according to claim 1, characterized in that: The impact cooling hole (33) is in the shape of a circle, an ellipse or a polygon.

3. The gas turbine stator blade structure according to claim 1, characterized in that: The impingement cooling hole (33) comprises an air inlet end (331) and an air outlet end (332), wherein the air inlet end (331) is located on a side of the impingement cooling plate (3) away from the end plate (2), and the air outlet end (332) is located on a side of the impingement cooling plate (3) close to the end plate (2), and the aperture of the air inlet end (331) is greater than or equal to the aperture of the air outlet end (332).

4. The gas turbine stator blade structure according to claim 1, characterized in that: The end plate (2) is provided with a first vent hole (25) penetrating the hollow cavity (11), and the impingement cooling plate (3) is also provided with a second vent hole (34) at a corresponding position, and the hydraulic diameters of the first vent hole (25) and the second vent hole (34) are larger than the hydraulic diameter of the impingement cooling hole (33).

5. The gas turbine stator blade structure according to claim 1, characterized in that: The positions corresponding to the impact cooling plate (3) and the end wall (21) after excluding the hollow cavity (11) are the first opening area (31), and the positions corresponding to the impact cooling plate (3) and the hollow cavity (11) are the second opening area (32); the distribution density of the impact cooling holes (33) in the first opening area (31) is greater than the distribution density in the second opening area (32).

6. A gas turbine stator blade structure according to any one of claims 1 to 5, characterized in that: The blade (1) includes a leading edge (12) and a trailing edge (13), a leading edge stagnation point (121) is provided at the leading edge (12), an outwardly convex area between the leading edge stagnation point (121) and the trailing edge (13) is defined as a suction surface (14), and an inwardly concave area between the leading edge stagnation point (121) and the trailing edge (13) is defined as a pressure surface (15), gill areas are provided on both sides of the leading edge (12), the gill area on the suction surface (14) is a suction surface gill area (16), and the gill area on the pressure surface (15) is a pressure surface gill area (17); the distribution density of the impingement cooling holes (33) at corresponding positions of the suction surface gill area (16) and the trailing edge (13) is greater than the distribution density at corresponding positions of the leading edge (12) of the blade.

7. A gas turbine stator blade structure according to claim 6, characterized in that: The concave area between the pressure surface gill area (17) and the trailing edge (13) is a throat area (18), and the distribution density of the impingement cooling holes (33) at corresponding positions in the throat area (18) is greater than the distribution density at corresponding positions on the blade leading edge (12).

8. The gas turbine stator blade structure according to claim 6, characterized in that: There are two end plates (2), which are respectively located at opposite ends of the blade (1); there are also two impingement cooling plates (3), which are respectively located on the outer surface of each end plate (2).

9. The gas turbine stator blade structure according to claim 8, characterized in that: The outer surface of the end plate (2) is recessed toward the end wall (21) to form a groove (24), and the cooling cavity (22) is formed by the impact cooling plate (3) and the bottom wall of the groove (24).

10. The gas turbine stator blade structure according to claim 9, characterized in that: The area between the blades (1) is provided with a plurality of end wall air film holes (23) on the area corresponding to the end plate (2).

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