An active control structure for suppressing secondary flow in turbine guide vane passage

Abstract

The present invention discloses an active control structure for suppressing secondary flow in a turbine guide vane channel. The upstream section of the turbine guide vane annular end wall is overlapped and sleeved outside the annular solid wall at the combustion chamber outlet. The annular slit structure between the two forms a cold air channel. The annular solid wall at the combustion chamber outlet includes a straight structure section and an inclined wedge-shaped structure section located downstream of the straight structure section and expanding outward. The inclined surface of the inclined wedge-shaped structure section is used to induce the mainstream gas to generate a velocity component perpendicular to the turbine guide vane annular end wall, and guide the mainstream gas to the wall surface of the turbine guide vane annular end wall. The leading edge portion of the upstream section of the turbine guide vane annular end wall is formed as a wedge-shaped structure with an inner wall facing outwardly inclined, so that the cold air channel is formed as a convergent channel along its inlet to outlet. The present invention can suppress the secondary flow in the turbine guide vane channel, reduce flow loss, improve the uniformity of the flow field at the turbine outlet, and improve the turbine performance.

Description

Technical Field

[0001] The present invention belongs to the field of turbines of ground gas turbines, aircraft engines and other impeller machines. It relates to an active control structure for suppressing secondary flow in a turbine guide vane channel, and more specifically, an active control strategy is adopted to suppress secondary flow in a high-pressure turbine guide vane channel at the outlet of a combustion chamber, thereby reducing flow loss, improving flow field uniformity at the turbine outlet, and improving turbine performance. Background Art

[0002] In modern ground-based gas turbines and aircraft engines, with the improvement of design level, the improvement of turbine efficiency through blade shape design has gradually approached the limit, and the potential for further improvement is limited. Improving turbine performance by reducing secondary flow losses is becoming more and more attractive.

[0003] According to the classical secondary flow theory of turbine blades, when the boundary layer near the wall approaches the leading edge of the blade, it convolutes to form a horseshoe vortex structure under the action of the leading edge potential flow effect and radial pressure. Therefore, the boundary layer of the incoming flow is an important source of secondary flow for turbine blades. Although the industry has recognized this, the boundary layer is an inherent property formed when the fluid passes through the solid surface under the action of viscosity, and the formation of the boundary layer cannot be avoided by changing the structure; and the longer the continuous flow of the fluid, the thicker the boundary layer.

[0004] Existing public technologies, such as leading edge modification technology or non-axisymmetric end wall technology, all act on the secondary flow that has already been formed. For example, the leading edge modification technology is mainly aimed at the formation stage of the horseshoe vortex at the leading edge of the blade. By increasing the rounding of the leading edge blade root, the local curvature here is reduced, thereby reducing the local pressure gradient and weakening the strength of the branches on both sides of the horseshoe vortex; while the non-axisymmetric end wall technology mainly works inside the blade channel, by improving the pressure distribution in the blade channel, weakening the migration of the channel vortex. Therefore, there is currently no public technology for active regulation of the incoming flow boundary layer. Summary of the invention

[0005] (I) Purpose of the invention

[0006] In view of the above-mentioned defects and shortcomings of the prior art, in order to suppress secondary flow such as in the high-pressure turbine guide vane channel located at the combustion chamber outlet, reduce flow losses, improve the flow field uniformity at the turbine outlet, improve turbine performance, and realize active regulation of the incoming flow boundary layer, the present invention provides an active control structure for suppressing secondary flow in the turbine guide vane channel.

[0007] (II) Technical solution

[0008] In order to achieve the purpose of the invention, the technical solution adopted by the present invention is as follows:

[0009] An active control structure for suppressing secondary flow in a turbine guide vane passage, comprising a combustion chamber outlet and a high-pressure turbine guide vane arranged downstream of the combustion chamber outlet, the high-pressure turbine guide vane comprising a turbine guide vane annular end wall and a plurality of turbine guide vane vanes uniformly arranged on the turbine guide vane annular end wall along the circumferential direction, the turbine guide vane annular end wall comprising a hub side annular end wall and a casing side annular end wall, a turbine guide vane passage is formed between two adjacent turbine guide vanes, and is characterized in that:

[0010] The upstream section of the hub-side annular end wall and / or the casing-side annular end wall of the turbine guide annular end wall is overlapped and sleeved outside the corresponding annular solid wall of the combustion chamber outlet, the overlap intrusion length L between the upstream section of the turbine guide annular end wall and the annular solid wall of the combustion chamber outlet, and there is a radius difference H between the upstream section of the turbine guide annular end wall and the annular solid wall of the combustion chamber outlet, so that the annular slit structure between the upstream section of the turbine guide annular end wall and the annular solid wall of the combustion chamber outlet is formed into a cold air channel, the combustion chamber outlet is used to introduce mainstream combustion gas into the turbine guide blade channel, the cold air channel is used to introduce two air flows into the turbine guide blade channel, and there is an axial distance S between the outlet of the cold air channel and the leading edge of each of the turbine guide blades;

[0011] The annular solid wall at the outlet of the combustion chamber includes a straight structure segment and an inclined wedge-shaped structure segment located downstream of the straight structure segment and expanding outwards, the outer wall surface of the inclined wedge-shaped structure segment has a first inclination angle β with the main axis, the inner wall surface of the inclined wedge-shaped structure segment close to the mainstream gas has a second inclination angle α with the main axis, the trailing edge of the inclined wedge-shaped structure segment is a sharp edge or a chamfered structure, and the inclined surface of the inclined wedge-shaped structure segment is used to induce the mainstream gas to generate a velocity component perpendicular to the annular end wall of the turbine guide device, so as to guide the mainstream gas to the wall surface of the annular end wall of the turbine guide device;

[0012] The inner wall surface of the annular end wall of the turbine guide vane is a straight structure as a whole, and the leading edge portion of the upstream section is formed into a wedge-shaped structure with an inner wall surface inclined outward, and a third inclination angle θ is formed between the inner wall surface of the wedge-shaped structure and the main axis;

[0013] The cold air passage is formed as a convergent passage from its inlet to its outlet.

[0014] Preferably, the height to length ratio H / L of the cold air passage is not less than 4.

[0015] Preferably, the first inclination angle β of the inclined wedge-shaped structure segment is 1° to 5°.

[0016] Preferably, the second inclination angle α of the inclined wedge-shaped structural segment is not greater than 8°, so as to avoid flow separation of the mainstream gas in its channel.

[0017] Preferably, the ratio d / h of the length d of the inclined wedge-shaped structure segment to the thickness h of the straight structure segment is not less than 5.

[0018] Preferably, there is a smooth transition with a rounded corner r1 between the straight structure segment and the inclined wedge-shaped structure segment of the annular solid wall at the combustion chamber outlet.

[0019] Preferably, there is a smooth transition with a rounded corner r2 between the wedge-shaped structure and the straight structure of the upstream section of the annular end wall of the turbine guide vane.

[0020] Preferably, by adjusting the relative size of the first inclination angle β and the second inclination angle α, it is ensured that the trailing edge of the inclined wedge-shaped structure segment is a sharp edge or a rounded structure to reduce the wake effect.

[0021] Preferably, the tip thickness w of the trailing edge of the inclined wedge-shaped structural segment is not greater than 0.2 mm, or the rounding R of the trailing edge of the inclined wedge-shaped structural segment is not greater than 0.2 mm.

[0022] In the active control structure for suppressing secondary flow in the turbine guide vane channel of the present invention, two air flows are introduced by utilizing the cold air channel between the annular solid wall of the combustion chamber and the annular end wall of the turbine guide vane.

[0023] Preferably, the momentum ratio between the two airflows at the inlet of the cold air channel and the mainstream combustion gas is not less than 4, the convergence of the two airflows through the cold air channel is accelerated, and at the outlet of the cold air channel, the momentum ratio of the two airflows to the mainstream is not less than 6, and the boundary layer of the two airflows is also significantly suppressed.

[0024] Preferably, the axial distance S between the outlet of the cold air channel and the leading edge of the turbine guide vane is determined according to the Reynolds number from the outlet of the two air flows to the leading edge, ensuring that the Reynolds number is not greater than 10. 4 .

[0025] Preferably, the wall surface of the turbine guide vane passage is a straight structure, and no local uneven surfaces such as steps, inner concave and outer convex are allowed. The two high-momentum airflows are blown out close to the wall surface and mixed with the mainstream boundary layer to increase the momentum of the fluid near the wall surface, thereby suppressing the appearance of the boundary layer. The Reynolds number at the leading edge of the turbine guide vane is controlled to prevent the boundary layer from growing again.

[0026] (III) Technical Effect

[0027] Compared with the prior art, the active control structure for suppressing the secondary flow in the turbine guide vane passage of the present invention can achieve the following effects:

[0028] (1) Simple structure. The active control structure for suppressing secondary flow in the turbine guide vane passage of the present invention does not increase the complexity of the structure. It can be simply modified on the existing gas turbine or applied to a newly designed gas turbine mainly by using the original components.

[0029] (2) Low manufacturing cost. Compared with other structures such as non-axisymmetric end walls and leading edge shaping for controlling secondary flow, the active control structure for suppressing secondary flow in the turbine guide vane channel of the present invention does not have any processing difficulties and is easy to implement.

[0030] (3) Significant effect: By adopting the active control structure for suppressing the secondary flow in the turbine guide vane channel of the present invention, the boundary layer characteristics of the turbine guide vane are changed, thereby suppressing the generation of horseshoe vortices, and further weakening the secondary flow in the guide vane channel, thereby reducing flow losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of an active control structure for suppressing secondary flow in a turbine guide vane passage according to the present invention;

[0032] Figure 2 for Figure 1 A magnified schematic diagram of the local structure. DETAILED DESCRIPTION

[0033] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, so that the advantages and features of the present invention can be more easily understood by those skilled in the art. It should be noted that the following is only a preferred embodiment of the present invention, but the content of the present invention is not limited to the following embodiments. In fact, various modifications and changes can be made in the present invention without departing from the scope or spirit of the present invention, which will be apparent to those skilled in the art. For example, the features shown or described as a part of an embodiment can be used together with another embodiment to produce another embodiment. Therefore, it is intended that the present invention includes such modifications and changes within the scope of the appended claims and their equivalents.

[0034] like Figure 1 , 2As shown, the active control structure for suppressing secondary flow in the turbine guide vane channel of the present invention includes a combustion chamber outlet 10 and a high-pressure turbine guide vane 20 arranged downstream of the combustion chamber outlet 10, the high-pressure turbine guide vane 20 includes a turbine guide vane annular end wall 21 and a plurality of turbine guide vanes 22 uniformly arranged on the turbine guide vane annular end wall 21 along the circumferential direction, the turbine guide vane annular end wall 21 includes a hub side annular end wall and a casing side annular end wall, and a turbine guide vane channel is formed between two adjacent turbine guide vanes 22. Among them, the upstream section of the hub-side annular end wall and / or the casing-side annular end wall of the turbine guide annular end wall 21 is overlapped and sleeved outside the corresponding annular solid wall 11 of the combustion chamber outlet 10, the overlap intrusion length L between the upstream section of the turbine guide annular end wall 21 and the annular solid wall 11 of the combustion chamber outlet, and there is a radius difference H between the upstream section of the turbine guide annular end wall 21 and the annular solid wall 11 of the combustion chamber outlet, so that the annular slit structure between the upstream section of the turbine guide annular end wall 21 and the annular solid wall 11 of the combustion chamber outlet is formed into a cold air channel 30, and the height and length ratio H / L of the cold air channel 30 is preferably not less than 4, the combustion chamber outlet 10 is used to introduce mainstream combustion gas into the turbine guide vane channel, the cold air channel 30 is used to introduce two airflows into the turbine guide vane channel, and there is an axial distance S between the outlet of the cold air channel 30 and the leading edge of each turbine guide vane 22.

[0035] The annular solid wall 11 of the combustion chamber outlet 10 includes a straight structure section and an inclined wedge-shaped structure section 12 located downstream of the straight structure section and expanding outward. There is a first inclination angle β between the outer wall surface of the inclined wedge-shaped structure section 12 and the main axis, and the first inclination angle β is preferably 1° to 5°. There is a second inclination angle α between the inner wall surface of the inclined wedge-shaped structure section 12 close to the mainstream gas and the main axis, and the second inclination angle α is preferably not greater than 8° to avoid the flow separation of the mainstream gas in its channel. By adjusting the relative size of the first inclination angle β and the second inclination angle α, it is ensured that the trailing edge of the inclined wedge-shaped structure section 12 is a sharp edge or a rounded structure to reduce the influence of the wake. The ratio d / h of the length d of the inclined wedge-shaped structure section 12 to the thickness h of the straight structure section is preferably not less than 5. There is a smooth transition of fillet r1 between the straight structure section and the inclined wedge-shaped structure section 12 of the annular solid wall of the combustion chamber outlet. The trailing edge of the inclined wedge-shaped structural segment 12 is a sharp edge or a rounded structure, and the thickness w of the sharp edge of the trailing edge of the inclined wedge-shaped structural segment 12 is not greater than 0.2 mm, or the rounding R of the trailing edge of the inclined wedge-shaped structural segment 12 is not greater than 0.2 mm. The inclined surface of the inclined wedge-shaped structural segment 12 is used to induce the mainstream gas to generate a velocity component perpendicular to the annular end wall 21 of the turbine guide device, and guide the mainstream gas to the wall surface of the annular end wall 21 of the turbine guide device.

[0036] The inner wall surface of the turbine guide annular end wall 21 is a straight structure as a whole, and the leading edge of the upstream section is formed into a wedge-shaped structure 23 with an inner wall surface inclined outward, and there is a third inclination angle θ between the inner wall surface of the wedge-shaped structure 23 and the main axis; the wedge-shaped structure and the straight structure of the upstream section of the turbine guide annular end wall are smoothly transitioned with a rounded corner r2. The cold air channel 30 is formed as a convergent channel from its inlet to its outlet.

[0037] In the active control structure for suppressing secondary flow in the turbine guide vane passage of the present invention, two air flows are introduced by utilizing the cold air passage 30 between the annular solid wall of the combustion chamber and the annular end wall of the turbine guide vane.

[0038] The momentum ratio between the two airflows and the mainstream gas at the inlet of the cold air channel 30 is preferably not less than 4. The convergence of the two airflows through the cold air channel 30 is accelerated. At the outlet of the cold air channel 30, the momentum ratio of the two airflows to the mainstream gas is not less than 6. At the same time, the boundary layer of the two airflows is also significantly suppressed. The axial distance S between the outlet of the cold air channel 30 and the leading edge of the turbine guide vane is determined according to the Reynolds number from the outlet of the two airflows to the leading edge, ensuring that the Reynolds number is not greater than 10. 4 The wall surface of the turbine guide vane passage is a straight structure, and no local uneven surfaces such as steps, concave or convex are allowed. The two high-momentum airflows are blown out close to the wall surface and mixed with the mainstream boundary layer, increasing the momentum of the fluid near the wall surface, thereby suppressing the appearance of the boundary layer. The Reynolds number at the leading edge of the turbine guide vane is controlled to prevent the boundary layer from growing again.

[0039] Through the above embodiments, the purpose of the present invention is fully and effectively achieved. Any equivalent or simple changes made according to the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. The technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all belong to the protection scope of the present invention.

[0040] The present invention does not elaborate on some of the well-known technologies that belong to those skilled in the art.

Claims

1. An active control structure for suppressing secondary flow in a turbine guide vane passage, comprising a combustion chamber outlet and a high-pressure turbine guide vane arranged downstream of the combustion chamber outlet, the high-pressure turbine guide vane comprising a turbine guide vane annular end wall and a plurality of turbine guide vanes uniformly arranged on the turbine guide vane annular end wall along the circumferential direction, the turbine guide vane annular end wall comprising a hub side annular end wall and a casing side annular end wall, a turbine guide vane passage is formed between two adjacent turbine guide vanes, characterized in that: The upstream section of the hub-side annular end wall and / or the casing-side annular end wall of the turbine guide annular end wall is overlapped and sleeved outside the corresponding annular solid wall of the combustion chamber outlet, the overlap intrusion length L between the upstream section of the turbine guide annular end wall and the annular solid wall of the combustion chamber outlet, and there is a radius difference H between the upstream section of the turbine guide annular end wall and the annular solid wall of the combustion chamber outlet, so that the annular slit structure between the upstream section of the turbine guide annular end wall and the annular solid wall of the combustion chamber outlet is formed into a cold air channel, the combustion chamber outlet is used to introduce mainstream combustion gas into the turbine guide blade channel, the cold air channel is used to introduce two air flows into the turbine guide blade channel, and there is an axial distance S between the outlet of the cold air channel and the leading edge of each of the turbine guide blades; The annular solid wall at the outlet of the combustion chamber includes a straight structure segment and an inclined wedge-shaped structure segment located downstream of the straight structure segment and expanding outwards, the outer wall surface of the inclined wedge-shaped structure segment has a first inclination angle β with the main axis, the inner wall surface of the inclined wedge-shaped structure segment close to the mainstream gas has a second inclination angle α with the main axis, the trailing edge of the inclined wedge-shaped structure segment is a sharp edge or a chamfered structure, and the inclined surface of the inclined wedge-shaped structure segment is used to induce the mainstream gas to generate a velocity component perpendicular to the annular end wall of the turbine guide device, so as to guide the mainstream gas to the wall surface of the annular end wall of the turbine guide device; The inner wall surface of the annular end wall of the turbine guide vane is a straight structure as a whole, and the leading edge portion of the upstream section is formed into a wedge-shaped structure with an inner wall surface inclined outward, and a third inclination angle θ is formed between the inner wall surface of the wedge-shaped structure and the main axis; The cold air passage is formed as a convergent passage from its inlet to its outlet.

2. The active control structure for suppressing secondary flow in a turbine guide vane passage according to claim 1, characterized in that: The height to length ratio H / L of the cold air passage is not less than 4.

3. The active control structure for suppressing secondary flow in a turbine guide vane passage according to claim 1, characterized in that: The first inclination angle β of the inclined wedge-shaped structure segment is 1° to 5°.

4. The active control structure for suppressing secondary flow in a turbine guide vane passage according to claim 1, characterized in that: The second inclination angle α of the inclined wedge-shaped structural segment is not greater than 8°, so as to avoid flow separation of the mainstream gas in its channel.

5. The active control structure for suppressing secondary flow in a turbine guide vane passage according to claim 1, characterized in that: The ratio d / h of the length d of the inclined wedge-shaped structural segment to the thickness h of the straight structural segment is not less than 5.

6. The active control structure for suppressing secondary flow in a turbine guide vane passage according to claim 1, characterized in that: There is a smooth transition with a rounded corner r1 between the straight structure section and the inclined wedge-shaped structure section of the annular solid wall at the combustion chamber outlet.

7. The active control structure for suppressing secondary flow in a turbine guide vane passage according to claim 1, characterized in that: There is a smooth transition with a rounded corner r2 between the wedge-shaped structure and the straight structure of the upstream section of the annular end wall of the turbine guide vane.

8. The active control structure for suppressing secondary flow in a turbine guide vane passage according to claim 1, characterized in that: By adjusting the relative size of the first inclination angle β and the second inclination angle α, it is ensured that the trailing edge of the inclined wedge-shaped structure segment is a sharp edge or a rounded structure, so as to reduce the wake effect.

9. The active control structure for suppressing secondary flow in a turbine guide vane passage according to claim 1, characterized in that: The tip thickness w of the trailing edge of the inclined wedge-shaped structural segment is not greater than 0.2 mm, or the rounding R of the trailing edge of the inclined wedge-shaped structural segment is not greater than 0.2 mm.

10. The active control structure for suppressing secondary flow in a turbine guide vane passage according to claim 1, characterized in that: The momentum ratio between the two airflows and the mainstream combustion gas at the inlet of the cold air channel is not less than 4, and the convergence of the two airflows through the cold air channel is accelerated. At the outlet of the cold air channel, the momentum ratio of the two airflows to the mainstream combustion gas is not less than 6, and the boundary layer of the two airflows is also significantly suppressed.

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