A moving blade structure and a gas turbine

Abstract

This invention relates to the field of gas turbine technology, and provides a moving blade structure and a gas turbine. The moving blade structure includes at least: a moving blade body, the tip of which has a first groove for reducing the leakage flow rate in the tip clearance; and a winglet structure disposed at the tip of the moving blade body and located on the suction side of the tip, extending from the leading edge to the trailing edge of the tip and having a predetermined width. The moving blade structure provided by this invention, by providing the winglet structure at the tip, increases the leading edge width of the tip, increases the amount of cool air entering the tip clearance through the leading edge, and reduces the amount of cool air directly entering the blade passage to merge with the mainstream high-temperature combustion gas, thereby improving the cooling efficiency of the cool air on the tip wall.

Description

Technical Field

[0001] This invention relates to the field of gas turbine technology, and more specifically to a moving blade structure and a gas turbine. Background Technology

[0002] A gas turbine consists of several turbine stages. Each stage contains a varying number of stationary blades and a varying number of moving blades. The stationary and moving blades are radially surrounded by endwalls and a casing. The endwalls are divided into two parts: the endwall connected to the root of the stationary blade is called the stationary endwall, and the endwall connected to the root of the moving blade is called the moving endwall. The stationary blades, stationary endwalls, and casing remain stationary during gas turbine operation, while the moving blades and moving endwalls rotate. To prevent friction between the moving blades and the casing during operation, a radial clearance, called the tip clearance, exists between them. The pressure distribution on the pressure side and suction side of the blade tip differs, creating a significant pressure gradient. Driven by this pressure gradient, the high-temperature gas flows through the tip clearance, forming a tip clearance leakage flow. This tip clearance leakage flow does not perform work on the moving blades, resulting in tip leakage losses and wasting the high-temperature gas. To reduce tip clearance leakage flow, modern gas turbines commonly employ grooved blade tips. This structure, by incorporating shoulder walls on both sides, alters the flow field characteristics within the tip clearance, significantly reducing leakage flow. However, the use of grooved blade tips generates pressure-side vortices and scraping vortices within the tip clearance, thereby increasing the thermal load on the blade tip surface. To further reduce the thermal load on the blade tip surface, establishing cooling slots at the leading edge of the blade tip is a common cooling method. By drawing high-pressure cold gas from the compressor outlet of the gas turbine, as this high-pressure cold gas flows out of the cooling slots and into the tip clearance, it forms a cold gas film on the blade tip surface. This film isolates the blade tip surface from the impact of the high-temperature combustion gas, reducing the thermal load and effectively providing cooling protection for the blade tip surface.

[0003] However, the traditional grooved blade tip structure has a narrow leading edge width, which means that only a portion of the cold air in the upstream casing cooling slot can enter the blade tip gap through the leading edge of the blade tip. The rest of the cold air will directly enter the blade passage and merge with the mainstream high-temperature combustion gas, resulting in a waste of cold air resources. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is that the existing grooved blade tip structure has a narrow blade tip leading edge width, which means that only part of the cold air in the upstream casing cooling slot can enter the blade tip gap through the blade tip leading edge position, and the rest of the cold air will directly enter the blade cascade channel and merge with the mainstream high temperature gas, resulting in a waste of cold air resources. Therefore, the present invention provides a moving blade structure and a gas turbine.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] On one hand, the present invention provides a moving blade structure, comprising at least: a moving blade body, wherein the blade tip of the moving blade body is provided with a first groove for reducing the leakage flow rate of the blade tip gap; and a winglet structure disposed at the blade tip of the moving blade body and located on the suction side of the blade tip, wherein the winglet structure extends from the leading edge of the blade tip to the trailing edge of the blade tip and has a preset width.

[0007] Furthermore, the winglet structure is provided with a second groove for reducing the leakage flow rate at the blade tip gap. The second groove is disposed adjacent to the first groove, and the extension direction of the second groove is consistent with the extension direction of the first groove.

[0008] Furthermore, the winglet structure has a notch on its bottom surface away from the blade tip, and the sidewall of the notch is an inclined surface. The distance between the inclined surface and the blade tip gradually decreases along the direction from the leading edge to the trailing edge of the blade tip.

[0009] Furthermore, the height of the moving blade body is denoted as H;

[0010] Let G be the height of the second groove wall, then 0.02H ≤ G ≤ 0.04H;

[0011] And / or, if the wall thickness of the second groove is denoted as K, then 0.01H≤K≤0.03H.

[0012] Furthermore, if the width of the winglet structure is denoted as W, then 0.05H≤W≤0.1H.

[0013] On the other hand, the present invention provides a gas turbine including the blade structure described in any of the above claims, and also including a casing;

[0014] A gap is left between the blade tip of the moving blade body and the inner wall of the casing to form a blade tip gap;

[0015] The casing is provided with cooling slots, the air inlet of the cooling slots is adapted to be connected to a cold air source, and the air outlet of the cooling slots is adapted to be set with the air inlet of the blade tip gap so that the cooling gas can enter the blade tip gap.

[0016] Furthermore, the cooling groove is inclined relative to the casing.

[0017] Furthermore, the angle between the cooling groove and the casing ranges from 20° to 40°.

[0018] Furthermore, the casing is provided with a step, the step surface on the side of the step closer to the blade tip gap is higher than the step surface on the side of the step away from the blade tip gap, and the height difference between the two step surfaces of the step is the same as the size of the blade tip gap;

[0019] The air outlet of the cooling groove is located on the step surface near the blade tip clearance;

[0020] The step surface on the side away from the blade tip gap has a predetermined gap with the leading edge of the blade tip.

[0021] Furthermore, if the width of the cooling groove is denoted as F, then 0.01H≤F≤0.03H.

[0022] The technical solution of this invention has the following advantages:

[0023] The moving blade structure provided by the present invention increases the leading edge width of the blade tip by setting a small wing structure at the blade tip position. This increases the amount of cold air entering the blade tip gap through the leading edge of the blade tip and reduces the amount of cold air that directly enters the blade cascade channel and merges with the mainstream high-temperature combustion gas, thereby improving the cooling efficiency of the cold air on the blade tip wall. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the moving blade structure in an embodiment of the present invention;

[0026] Figure 2 This is a partial enlarged schematic diagram of the moving blade structure in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the blade tip gap flow in the moving blade structure of this invention embodiment;

[0028] Figure 4 This is a schematic diagram of the flow field in the blade cascade channel of the moving blade structure in an embodiment of the present invention;

[0029] Figure 5 This is a cross-sectional view of the meridional plane of the blade passage of the gas turbine in an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of the cooling slots in a gas turbine according to an embodiment of the present invention.

[0031] 1. Moving blade body; 2. Blade tip; 3. Airfoil structure; 4. Stationary blade; 5. Stationary blade end wall; 6. Moving blade end wall; 7. Leading edge of blade tip; 8. Trailing edge of blade tip; 9. First groove; 10. Second groove; 11. Pressure side shoulder wall; 12. Intermediate shoulder wall; 13. Suction side shoulder wall; 14. Casing; 15. Blade tip clearance; 16. Cooling groove; 17. Step; 18. Notch; 19. Inclined surface; 20. Pressure side angular vortex; 21. Scraping vortex; 22. Airfoil pressure side angular vortex; 23. Airfoil scraping vortex; 24. Leakage vortex. Detailed Implementation

[0032] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] like Figure 1 , Figure 2As shown, this embodiment provides a moving blade structure, which includes at least: a moving blade body 1, the blade tip 2 of the moving blade body 1 is provided with a first groove 9 for reducing the leakage flow rate of the blade tip gap 15; a winglet structure 3, which is provided at the blade tip 2 of the moving blade body 1 and located on the suction side of the blade tip 2, the winglet structure 3 extends from the leading edge 7 of the blade tip to the trailing edge 8 of the blade tip and has a preset width.

[0037] The moving blade structure provided in this embodiment increases the width of the leading edge 7 of the blade tip by setting a small wing structure 3 at the blade tip 2. This increases the amount of cold air entering the blade tip gap 15 through the leading edge 7 of the blade tip, while reducing the amount of cold air that directly enters the blade passage and merges with the mainstream high-temperature combustion gas, thereby improving the cooling efficiency of the cold air on the blade tip wall.

[0038] The wall cooling efficiency η is defined as follows:

[0039]

[0040] In the formula: T ∞ T represents the turbine's mains temperature (unit: K); w T is the tip wall temperature (unit: K); C The temperature of the cold air (unit: K) is the blade tip wall temperature T as the amount of cold air entering the blade tip gap increases. w The pressure will decrease, and at this point, the cooling efficiency of the blade tip wall will be improved.

[0041] The winglet structure 3 is provided with a second groove 10 to reduce the leakage flow rate at the blade tip clearance. The second groove 10 is adjacent to the first groove 9, and the extension direction of the second groove 10 is consistent with the extension direction of the first groove 9. The pressure side of the first groove 9 is a pressure-side shoulder wall 11, and the suction side is a middle shoulder wall 12. The pressure side of the second groove 10 is a middle shoulder wall 12, and the suction side is a suction-side shoulder wall 13. The blade tip 2 has three shoulder walls: pressure-side shoulder wall 11, middle shoulder wall 12, and suction-side shoulder wall 13. Preferably, the widths of the middle shoulder wall 12, suction-side shoulder wall 13, and pressure-side shoulder wall 11 are equal. Figure 3 As shown, due to the geometric effects of the pressure-side shoulder wall 11 and the suction-side shoulder wall 13, a pressure-side angular vortex 20 and a scraping vortex 21 are formed in the first groove 9. The two vortices rotate in opposite directions, forming a reverse vortex pair. This reverse vortex pair drives the leakage flow in the blade tip gap 15 to pass through the blade tip gap 15 in an S-shaped flow trajectory. At this time, the leakage flow in the blade tip gap 15 flows from the pressure side of the blade tip 2 to the suction side of the blade tip 2. During the flow, the pressure-side shoulder wall 11, the first groove 9, and the intermediate shoulder wall 12 form a labyrinth-like sealing structure, which reduces the flow area and slows down the flow velocity of the leakage flow in the blade tip gap 15, thus reducing the flow rate of the leakage flow in the blade tip gap 15.

[0042] Furthermore, due to the addition of a second groove 10 and a suction-side shoulder wall 13 on the suction side of the blade tip 2, similar pressure-side vortex 20 and scraping vortex 21 are formed in the second groove 10, in addition to the pressure-side vortex 20 and scraping vortex 21 in the original first groove 9. These are referred to as winglet pressure-side vortex 22 and winglet scraping vortex 23. The opposing vortex pair formed by the winglet pressure-side vortex 22 and winglet scraping vortex 23 also drives the blade tip gap leakage flow to pass through the blade tip gap 15 above the winglet structure 3 in an S-shaped flow trajectory. Therefore, the leakage flow in the blade tip gap 15 exhibits a double S-shaped flow characteristic. Under the action of the double labyrinth seal structure, the flow area of ​​the blade tip gap leakage flow is further reduced, the flow velocity is further slowed down, and the flow rate of the blade tip gap leakage flow is thus further reduced.

[0043] Moreover, due to the effect of the double labyrinth seal structure, the leakage velocity in the blade tip gap is reduced, and the impact on the walls of the first groove 9 and the second groove 10 is weakened, which will improve the heat exchange condition of the wall to a certain extent.

[0044] The convective heat transfer coefficient h is defined as follows (unit: W / (K·m)). 2 )):

[0045]

[0046] In the formula: q is the heat flux density of the blade tip wall (unit: W / m³). 2 ); T a Temperature of the fluid near the blade tip wall (unit: K); T w The temperature of the blade tip wall is K. When the impact force weakens, the heat flux density q at the blade tip wall decreases, and the heat transfer coefficient at the blade tip wall decreases.

[0047] In this design, the winglet structure 3 has a notch 18 on its bottom surface away from the blade tip 2. The sidewall of the notch 18 is an inclined surface 19, and the distance between the inclined surface 19 and the blade tip 2 gradually decreases along the direction from the leading edge 7 of the blade tip to the trailing edge 8 of the blade tip. Because leakage vortices 24 and upper channel vortices exist in the blade cascade channel near the suction side of the blade tip 2, the fluid in these two vortices will dissipate, reducing work capacity and significantly decreasing the aerodynamic performance of the turbine stage. Figure 4 As shown, however, after the winglet structure 3 is set, due to the influence of the geometry of the winglet structure 3, the leakage vortex 24 and the upper channel vortex are mixed and merged into the leakage vortex 24, which reduces the dissipation caused by fluid rotation and increases the aerodynamic performance of the turbine stage.

[0048] For example, let the height of the moving blade body 1 be denoted as H; let the height of the groove wall of the second groove 10 be denoted as G, then 0.02H ≤ G ≤ 0.04H, for example, G = 0.02H, or G = 0.03H; and / or, let the thickness of the groove wall of the second groove 10 be denoted as K, then 0.01H ≤ K ≤ 0.03H, for example, K = 0.01H, or K = 0.02H. For example, let the width of the winglet structure 3 be denoted as W, then 0.05H ≤ W ≤ 0.1 H, for example, W = 0.08 H. For example, the width of the winglet structure 3 can vary along the axial direction, and the width of the winglet structure can be 0 at the leading edge 7 and trailing edge 8 of the blade tip. It should be noted that in specific implementation and application, due to different gas turbine models, the shape of the blade tip 2 varies to some extent, and the shape and size of the winglet structure 3 can be designed according to actual needs. When gas turbine designers add a winglet structure 3 to the suction side of the blade tip 2, they need to determine the width ratio of the winglet structure 3 to the original blade tip: generally, the width of the winglet structure 3 is 50% of the original blade tip width.

[0049] like Figure 5 As shown, another embodiment provides a gas turbine, including a casing 14. The gas turbine also includes several turbine stages, each turbine stage comprising a varying number of stationary blades 4 and a varying number of moving blade bodies 1. The stationary blades 4 and the moving blade bodies 1 are radially surrounded by end walls and the casing 14. The end walls are divided into two parts: the end wall to which the root of the stationary blade 4 is connected is called the stationary blade end wall 5, and the end wall to which the root of the moving blade body 1 is connected is called the moving blade end wall 6. The stationary blades 4, the stationary blade end wall 5, and the casing 14 remain stationary during gas turbine operation, while the moving blade bodies 1 and the moving blade end wall 6 remain rotating. To avoid friction between the moving blade bodies 1 and the casing 14 during gas turbine operation, a radial clearance, called the blade tip clearance 15, exists between the moving blade bodies 1 and the casing 14. For example, the size of the blade tip clearance 15 can be 0.01 times the height of the moving blade body 1.

[0050] like Figure 6 As shown, the casing 14 is provided with a cooling slot 16. For example, if the width of the cooling slot 16 is denoted as F, then 0.01H ≤ F ≤ 0.03H. For example, F = 0.01H or F = 0.02H. The air inlet of the cooling slot 16 is adapted to be connected to a cold air source, and the air outlet of the cooling slot 16 is adapted to be set in the air inlet of the blade tip clearance 15 so that the cooling gas can enter the blade tip clearance 15.

[0051] For example, the cooling slot 16 can be set at an angle relative to the casing 14.

[0052] For example, the included angle between the cooling slot 16 and the casing 14 is in the range of 20°-40°, and preferably, the included angle between the cooling slot 16 and the casing 14 can be 30°.

[0053] The casing 14 is provided with a step 17. The step surface of the step 17 on the side closer to the blade tip gap 15 is higher than the step surface of the step 17 on the side away from the blade tip gap 15. The height difference between the two step surfaces of the step 17 is the same as the size of the blade tip gap 15. The air outlet of the cooling groove 16 is located on the step surface of the step 17 on the side closer to the blade tip gap 15. There is a preset gap between the step surface of the step 17 on the side away from the blade tip gap 15 and the leading edge 7 of the blade tip. The size of the preset gap can be designed according to actual needs. This setting can prevent the step 17 and the leading edge 7 of the blade tip from rubbing during the operation of the gas turbine.

[0054] In summary, the blade structure and gas turbine described in this application can reduce the flow rate of the tip clearance leakage flow. After adding the winglet structure 3 to the suction side of the blade tip 2, since the winglet structure 3 is also composed of shoulder walls on both sides and a groove in the middle, it will also form a labyrinth-like seal structure. Combined with the original labyrinth-like seal structure, the blade tip 2 now exhibits the characteristics of a double labyrinth seal structure. Under the action of the double labyrinth seal structure, the flow area of ​​the tip clearance leakage flow is further reduced, and the flow velocity is further slowed down, thus further reducing the flow rate of the tip clearance leakage flow.

[0055] The blade structure and gas turbine in this application can reduce the heat transfer coefficient of the blade tip wall. After adding the small airfoil structure 3 to the suction side of the blade tip 2, the leakage velocity of the blade tip gap is reduced due to the effect of the double labyrinth seal structure, the impact on the blade tip wall is weakened, and the heat transfer condition of the blade tip wall will be improved to a certain extent.

[0056] The blade structure and gas turbine in this application can improve the cooling efficiency of the blade tip wall. After adding the winglet structure 3 to the suction side of the blade tip 2, the width of the leading edge 7 of the blade tip is increased, the amount of cold air entering the blade tip gap 15 through the leading edge 7 of the blade tip increases, and the amount of cold air that directly enters the blade passage and merges with the mainstream high-temperature gas is reduced, thereby improving the cooling efficiency of the blade tip wall.

[0057] The moving blade structure and gas turbine in this application can improve the aerodynamic performance of the blade cascade passage. After adding the winglet structure 3 to the suction side of the blade tip 2, the leakage vortex 24 and the upper passage vortex are mixed and merged into the leakage vortex 24 due to the influence of the geometry of the winglet structure 3, which reduces the dissipation caused by fluid rotation and increases the aerodynamic performance of the turbine stage.

[0058] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A gas turbine, characterized in that, include: The moving blade structure includes: The blade body has a first groove at its tip to reduce the leakage flow rate at the blade tip gap. A winglet structure is provided at the tip of the blade body and located on the suction side of the blade tip. The winglet structure extends from the leading edge of the blade tip to the trailing edge of the blade tip and has a preset width. The winglet structure is provided with a second groove for reducing the leakage flow rate at the blade tip clearance. The second groove is disposed adjacent to the first groove, and the extension direction of the second groove is consistent with the extension direction of the first groove. The height of the moving blade body is denoted as H; Let the width of the winglet structure be W, then 0.05H≤W≤0.1H; Casing; A gap is left between the blade tip of the moving blade body and the inner wall of the casing to form a blade tip gap; The casing is provided with cooling slots, the air inlet of the cooling slots is adapted to be connected to a cold air source, and the air outlet of the cooling slots is adapted to be set with the air inlet of the blade tip gap so that the cooling gas can enter the blade tip gap.

2. The gas turbine according to claim 1, characterized in that, The winglet structure has a notch on its bottom surface away from the blade tip. The sidewall of the notch is an inclined surface, and the distance between the inclined surface and the blade tip gradually decreases along the direction from the leading edge to the trailing edge of the blade tip.

3. The gas turbine according to claim 1, characterized in that, Let G be the height of the second groove wall, then 0.02H ≤ G ≤ 0.04H; And / or, if the wall thickness of the second groove is denoted as K, then 0.01H≤K≤0.03H.

4. The gas turbine according to claim 1, characterized in that, The cooling slots are inclined relative to the casing.

5. The gas turbine according to claim 4, characterized in that, The angle between the cooling groove and the casing ranges from 20° to 40°.

6. The gas turbine according to claim 1, characterized in that, The casing is provided with a step, the step surface near the blade tip gap is higher than the step surface away from the blade tip gap, and the height difference between the two step surfaces is the same as the size of the blade tip gap. The air outlet of the cooling groove is located on the step surface near the blade tip clearance; The step surface on the side away from the blade tip gap has a predetermined gap with the leading edge of the blade tip.

7. The gas turbine according to claim 1, characterized in that, The width of the cooling groove is denoted as F, and then 0.01H≤F≤0.03H.

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