CN116398250A - Structure for improving low-pressure turbine blade cascade aerodynamic efficiency - Google Patents

Abstract

The invention provides a structure for improving the aerodynamic efficiency of a low-pressure turbine blade cascade, comprising: an end wall and a blade body; the end wall is a surface of the blade cascade channel perpendicular to the blade body; several first depressions are arranged on the end wall Structure, several first concave structures are located between two adjacent blade bodies, the first concave structures are used to enhance the momentum exchange between the boundary layer flow and the external mainstream, enhance the kinetic energy of the flow near the wall, and change the direction of the flow near the wall; the blade body A blade suction surface and a blade pressure surface are arranged on the blade, the blade suction surface is the convex surface of the blade body, and the blade pressure surface is the inner concave surface of the blade body; the blade suction surface is provided with several second concave structures, and the second concave structures are used to suppress The flow separation on the blade suction surface and the avoidance of separation vortices. The invention utilizes the concave structure on the blade suction surface and the end wall to significantly improve the flow of the cascade passage, reduce the aerodynamic loss of the low-pressure turbine blade cascade, and improve the aerodynamic efficiency of the turbine.

Description

Structures for Improving Aerodynamic Efficiency of Low Pressure Turbine Cascades

technical field

The invention relates to the technical field of aerodynamic equipment, in particular to a structure for improving the aerodynamic efficiency of a low-pressure turbine cascade.

Background technique

In an aviation turbofan engine, the output of the low-pressure turbine is used to drive the turbofan engine's fan, which drives a large volume of air through the engine and generates the main engine thrust. Therefore, the working efficiency and aerodynamic performance of the low-pressure turbine have an important influence on the engine performance.

The development of modern aero-engines puts forward lightweight and high-efficiency requirements for low-pressure turbines. Therefore, the number of blades of low-pressure turbines needs to be reduced, and the load on the blades of low-pressure turbines is increasing. As a result, the distance between blades of low-pressure turbines increases. , the flow between the blades is more complicated, and the secondary flow loss on the end wall of the cascade increases, so the aerodynamic loss of the low-pressure turbine cascade increases, and the aerodynamic efficiency of the low-pressure turbine decreases, which will reduce the flow capacity of the low-pressure turbine and reduce the Turbo energy conversion efficiency increases engine fuel consumption.

The patent document with the publication number CN105507955A discloses a design method of a high-pressure turbine transonic guide vane cascade. The design method of a high-pressure turbine transonic guide vane cascade includes the following steps: Enhancing the inlet of the cascade channel to the area in front of the geometric throat of the cascade channel The load of the cascade is divided into the front area, the throat area and the diffusion area; the acceleration of the airflow in the front area is improved, and the length of the diffusion area is increased; the expansion acceleration of the supersonic air flow in the throat area is weakened; the airflow in the diffusion area is reduced Acceleration; in the diffusion area, a compression wave is constructed near the exit of the channel for deceleration; the design of the cascade is completed according to the cascade 11 parameter modeling method. But this patent document is not applicable to the low-pressure turbine, and the technical solution is different from the present application.

Contents of the invention

In view of the defects in the prior art, the purpose of the present invention is to provide a structure for improving the aerodynamic efficiency of the low-pressure turbine blade cascade.

A structure for improving the aerodynamic efficiency of a low-pressure turbine blade cascade according to the present invention includes: an end wall and a blade body; the end wall is a surface of a cascade passage perpendicular to the blade body;

The end wall is provided with several first recessed structures, and the several first recessed structures are located between two adjacent blade bodies, and the first recessed structures are used to enhance the connection between the boundary layer flow and the external mainstream. momentum exchange;

The blade body is provided with a blade suction surface and a blade pressure surface, the blade suction surface is an outer convex surface of the blade body, and the blade pressure surface is an inner concave surface of the blade body;

The suction surface of the blade is provided with several second concave structures, and the second concave structures are used to suppress flow separation on the suction surface of the blade and avoid generation of separation vortices.

Preferably, several of the first concave structures are arranged along an arrangement line, and the arrangement line is parallel to the middle arc of the blade body.

Preferably, there are multiple second depression structures, and the depth of the second depression is 0-6.0mm;

Every pair of the second concave structures forms a V-shaped structure, and several V-shaped structures are formed on the suction surface of the blade.

Preferably, the second concave structure is arranged close to the most convex position of the blade body, and is located downstream of the most convex position on the surface at a distance of 0.1 to 10 times the diameter d of the depression.

Preferably, the ratio of the concave diameter d of the first concave structure to the blade pitch P of the blade body is 0.01-0.2;

The ratio of the recess depth h of the first recess structure to the recess diameter d of the first recess structure is 0.05˜0.3.

Preferably, the ratio of the axial arrangement spacing s _x of the first concave structure to the concave diameter d of the first concave structure is 1.1-1.5;

From the upstream, the distance between the central point of the first one of the first concave structures on the arrangement line and the inlet section of the cascade is 1.0-1.5d;

The axial distance between the center points of the first and last two first concave structures on the arrangement line is L=5-10d, and the axial distance between the first concave structure at the tail and the outlet section of the cascade is The distance is 0.25 to 0.5 times the chord length Cx.

Preferably, the first concave structures are arranged at a position of 0.5P to 0.8P in the circumferential direction of the cascade channel, P is the blade pitch of the blade body, and the distance between the first concave structures and the adjacent blade pressure face closer.

Preferably, from upstream, the first one of the first recessed structures is located 1.0d to 1.5d upstream of the inlet section of the cascade, and the most downstream first recessed structure is located 0.2d upstream of the outlet section of the cascade. ~0.5 times the position of the chord length c _x ;

d is the concave diameter of the first concave structure, and the value of d is 1.0-50mm; c _x is the length of the blade body in the cascade axial direction, and the length of c _x is 5-20 times the concave diameter d.

Compared with the prior art, the present invention has the following beneficial effects:

1. In the present invention, by arranging the second concave structure on the suction surface of the low-pressure turbine blade and the first concave structure on the end wall of the turbine blade cascade, the movement direction of the fluid near the wall is changed, and the aerodynamic efficiency of the low-pressure turbine blade cascade is improved. By arranging the second concave structure on the suction surface of the low-pressure turbine blade, the inner arc surface of the second concave structure interacts with the relatively low-speed near-wall fluid, and a near-wall flow direction vortex system is induced downstream of the second concave structure, increasing The momentum exchange between the near-wall flow and the mainstream flow is increased. At the same time, the flow shear induced by the near-wall flow to the vortex system promotes the transition of the near-wall flow, which enhances the ability of the near-wall fluid to overcome the reverse pressure gradient, and finally causes the flow on the blade suction surface The laminar flow separation phenomenon weakens or disappears, thereby reducing the shear of the laminar flow separation backflow area and the main flow, reducing the flow wake of the cascade, thereby reducing the loss of the blade shape caused by both blade shapes;

2. The present invention interacts with the secondary vortex on the surface of the end wall of the low-pressure turbine blade cascade to generate a vortex, enhance the movement energy of the fluid near the wall, and change the direction of movement of the vortex, suppressing The vortex accumulates toward the suction side of the adjacent blade; weakens the strength of the horseshoe vortex at the root of the leading edge of the blade, making it develop and induce the secondary vortex system at the end of the cascade, such as the channel vortex, corner vortex, and trailing edge shedding vortex. is also weakened, thereby reducing the secondary flow loss caused by it;

3. The present invention suppresses or weakens the lateral flow of the end wall through the design that the first concave arrangement line on the surface of the end wall of the low-pressure turbine cascade is parallel to the arc of the blade, and suppresses the horseshoe vortex on the opposite end wall in the cascade passage. The effect of the development of the secondary flow also weakens the strength of the secondary flow vortex system in the end area of the blade cascade, thereby reducing the loss of the secondary flow caused by it;

4. The present invention solves the problem of the reduction of aerodynamic efficiency caused by the secondary flow on the end wall of the low-pressure turbine blade cascade. At the same time, the concave arrangement used in the present invention has a simple processing technology and is effective under the condition of a wide incoming flow Reynolds number, especially for super The aerodynamic efficiency of the high-load low-pressure turbine cascade has been significantly improved.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 is the dimensional structure schematic diagram of the structure for improving the aerodynamic efficiency of low-pressure turbine cascade of the present invention;

Fig. 2 is a flow schematic diagram 1 of a structure for improving the aerodynamic efficiency of a low-pressure turbine cascade according to the present invention;

Fig. 3 is the flow diagram II of the structure for improving the aerodynamic efficiency of the low-pressure turbine cascade of the present invention;

Fig. 4 is a schematic diagram highlighting the second concave structure of the structure for improving the aerodynamic efficiency of the low-pressure turbine cascade of the present invention;

FIG. 5 is a schematic diagram highlighting the first concave structure of the structure for improving the aerodynamic efficiency of the low-pressure turbine cascade of the present invention.

The figure shows:

Blade body 1 First concave structure 201

Blade suction surface 101 Arrangement line 3

Arc line 4 in the second concave structure 1011

Blade pressure surface 102 Cascade inlet section 5

End wall 2 Cascade outlet section 6

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Example 1:

As shown in Figures 1 to 4, this embodiment provides a structure for improving the aerodynamic efficiency of a low-pressure turbine cascade, including: an end wall 2 and a blade body 1, and the end wall 2 is a cascade passage perpendicular to the blade body 1 On the surface, the end wall 2 is provided with several first concave structures 201, and the several first concave structures 201 are located between two adjacent blade bodies 1, and the first concave structures 201 are used to enhance the momentum of the boundary layer flow and the external main flow To exchange and change the flow direction near the wall, the blade body 1 is provided with a blade suction surface 101 and a blade pressure surface 102, the blade suction surface 101 is the outer convex surface of the blade body 1, the blade pressure surface 102 is the inner concave surface of the blade body 1, and the blade suction The surface 101 is provided with several second concave structures 1011, and the second concave structures 1011 are used to suppress flow separation on the suction surface 101 of the blade and avoid generation of separation vortices.

The leading edge of the blade body 1 is tangent to the cascade inlet section 5 , and the trailing edge of the blade body 1 is tangent to the cascade outlet section 6 .

There are multiple second recessed structures 1011, the depth of the second recesses is 0-6.0mm, every two second recessed structures 1011 form a pair of V-shaped structures, and several V-shaped structures are formed on the suction surface 101 of the blade. The second concave structure 1011 is arranged close to the most convex position of the blade body 1 , and is located downstream of the most convex position on the surface at a distance of 0.1-10 times the diameter d of the depression.

Several first concave structures 201 are arranged along the arrangement line 3 , and the arrangement line 3 is parallel to the central arc 4 of the blade body 1 .

The ratio of the axial arrangement distance s _x of the first concave structures 201 to the concave diameter d of the first concave structures 201 is 1.1 to 1.5. The distance between the entrance section of the grid is 1.0-1.5d, the axial distance between the center points of the first and last two first concave structures 201 on the arrangement line 3 is L=5-10d, and the first concave structure 201 at the tail and the vane The axial distance of the gate outlet section 6 is 0.25-0.5 times the chord length Cx.

The ratio of the concave diameter d of the first concave structure 201 to the blade pitch P of the blade body 1 is 0.01-0.1, and the ratio of the concave depth h of the first concave structure 201 to the concave diameter d of the first concave structure 201 is 0.05-0.3 .

From the upstream, the first first concave structure 201 is located 1.0d to 1.5d upstream of the cascade inlet section 5, and the most downstream first concave structure 201 is located 0.2 to 0.5 times the chord length upstream of the cascade outlet section 6 The position of c _x , d is the concave diameter of the first concave structure 201, the value of d is 1.0-50mm, c _x is the length of the blade body 1 in the axial direction of the cascade, and the length of c _x is 5-20 times the diameter of the concave d .

The first concave structures 201 are arranged at positions 0.5P to 0.8P in the circumferential direction of the cascade passage, where P is the blade pitch of the blade body 1 , and the first concave structures 201 are arranged closer to the pressure surfaces of adjacent blades.

This embodiment can reduce the secondary flow loss in the end area of the low-pressure turbine cascade, improve the aerodynamic efficiency of the low-pressure turbine cascade, suppress the secondary flow vortex system in the end area of the low-pressure turbine cascade, or weaken the intensity of the secondary flow vortex system, and reduce the Secondary flow loss in the end zone, improving the aerodynamic efficiency of the low pressure turbine cascade.

In the structure of this embodiment, the first concave structures 201 are arranged on the end wall 2, and the arrangement curve of the first concave structures 201 is parallel to the arc line 4 of the blade, as shown in Figure 2 and Figure 3, when the airflow A flows through When the end wall 2 impacts the root of the leading edge of the blade body 1, due to the low flow velocity in the boundary layer, the boundary layer flow will form a multi-layer horseshoe vortex structure at the root of the blade leading edge, and the horseshoe vortex will develop into a channel vortex B with oblique flow. And induce the angular vortex at the root of the suction surface 101 of the adjacent blade and the shedding vortex D at the trailing edge of the blade. These vortex structures are called the secondary flow vortex system in the end region of the cascade.

In the structure of this embodiment, the first concave structure 201 on the wall surface of the end wall 2 can enhance the momentum exchange between the boundary layer flow and the external main flow, and the kinetic energy of the boundary layer flow near the wall surface can be enhanced. When the secondary flow from the blade pressure surface 102 passes over the first concave structure 201 on the end wall 2, it will rush into the interior of the first concave structure 201 and interact with the curved wall surface of the first concave structure 201, the first concave structure 201 changes the flow direction of the near-wall vortex, so that the near-wall vortex flows into the main flow and obtains the energy to flow downstream, which reduces the accumulation and intrusion of the secondary flow and the low-energy flow near the suction surface 101 of the adjacent blade, thus weakening the end wall 2 Transverse flow, inhibit or weaken the horseshoe vortex structure and vortex strength, thereby weakening the secondary flow vortex system in the end area of the blade cascade and the secondary flow loss caused by it.

In the structure of this embodiment, a second concave structure 1011 is arranged on the suction surface 101 of the turbine blade, and the second concave structures 1011 are arranged in pairs on the suction surface 101 of the blade in a V shape, and there is a gap between the second concave structure 1011 and the airflow Inclination angle β, generally, the second concave structure 1011 is arranged near the downstream of the most convex position of the blade suction surface 101 . The second concave shape is oblong or spherical.

In the structure of this embodiment, the second concave structure 1011 on the blade suction surface 101 plays the role of inhibiting the flow separation on the blade suction surface 101 and avoiding the separation vortex, and reduces the aerodynamic loss caused by the separation vortex, and also plays a role The entrainment effect of the separation vortex on the channel vortex B on the blade suction surface 101 is suppressed, the aerodynamic loss is reduced, the flow of the cascade channel is significantly improved, and the aerodynamic efficiency of the turbine is improved.

Specific geometrical parameters of the preferred dimpled junction for applications on ultra-highly loaded low-pressure turbine cascades:

a. The relative diameter of the concave structure d/P (diameter of the concave structure/blade pitch) = 0.077, 0.01 ~ 0.1;

b. Depth-to-diameter ratio of the depressed structure h/d (depth of depressed structure/diameter of depressed structure) = 0.15, 0.1 to 0.2;

c. The relative arrangement distance of the recessed structure in the axial direction s _x /d (the axial arrangement distance of the recessed structure/the diameter of the recessed structure) = 1.2;

d. The relative arrangement spacing of the concave structure in the circumferential direction s _θ /P (circumferential arrangement spacing of the concave structure/blade pitch) = 0.1;

e. For the first recessed structure 201, calculated from the center point of the first upstream recess, the first first recessed structure 201 protrudes 1.2d from the entrance section of the cascade;

f. For the first concave structure 201, the axial length of the arrangement of the first concave structure 201 is 7.2d based on the distance between the center points of the head and tail depressions;

g. The first concave structure 201 is arranged at a position of 0.6P in the circumferential direction of the cascade channel, closer to the pressure side;

h. The arrangement curve of the first concave structure 201 is parallel to the central arc 4 of the blade.

Example 2:

Those skilled in the art may understand this embodiment as a specific description of Embodiment 1.

As shown in FIG. 1 , a row of second recessed structures 1011 is arranged on the blade suction surface 101 , and a row of first recessed structures 201 is arranged on the end wall 2 . The cascade axial distance between the first second concave structure 1011 and the cascade inlet section 5 is x _b . For the first concave structure 201 , the diameter of a single first concave structure 201 is d, and the distance between adjacent first concave structures 201 in the cascade axial direction is s _x . The total length of a row of first recessed structures 201 in the axial direction of the cascade is L=7.2d, and the upstream length from the inlet section 5 of the cascade is l.

The first concave structure 201 is arranged along the arrangement line 3, which is parallel to the blade center arc 4, and the distance between the arrangement line 3 and the blade center arc 4 in the cascade circumferential direction is p. The arrangement pitch of the blade bodies 1 in the circumferential direction of the cascade is P, and the length of the blade bodies 1 in the axial direction of the cascade is c _x . The blade body 1 is tangent to the blade cascade inlet section 5 at the leading edge of the blade, and the blade body 1 is tangent to the blade cascade outlet section 6 at the blade trailing edge.

The first concave structure 201 arranged on the wall surface of the end wall 2 induces the main flow to interact with it, and generates a spiral vortex near the wall, which promotes the momentum exchange between the low-velocity fluid in the boundary layer near the wall and the high-speed fluid in the main flow, and enhances the kinetic energy of the fluid near the wall. To resist the lateral pressure gradient in the cascade channel, reduce the deflection of the fluid near the wall to the suction side, thereby reducing the flow into the horseshoe vortex on the suction side of the blade, and weakening the strength of the horseshoe vortex on the suction side.

The arrangement line 3 of the first concave structure 201 is parallel to the mid-arc line 4 of the blade, and the spiral vortex near the wall formed by it blocks the cross-flow flow from the pressure side to the suction side, and promotes this part of the near-wall fluid to flow in the direction of the mid-arc line 4 of the blade. , to improve the flow tissue structure in the near-wall region.

The spanwise position of the arrangement of the first concave structure 201 just intercepts the weak point of the horseshoe vortex on the pressure side, and the swirling flow in the horseshoe vortex on the pressure side will rush into the first concave structure 201 and interact with the wall surface of the first concave structure 201 to generate a vortex. The kinetic energy of the horseshoe vortex on the pressure side is diffused, and the intensity of the horseshoe vortex on the pressure side is weakened.

The above effects on the suction-side horseshoe vortex, the pressure-side horseshoe vortex, and the flow organization structure in the near-wall region will eventually weaken the strength of the channel vortex and other secondary flow vortex systems, reduce the unnecessary flow shear, and finally reduce the secondary flow loss , improve the flow velocity, flow direction distribution and flow performance in the cascade channel, and improve the efficiency of the low-pressure turbine.

The arranged first concave structures 201 come out from the inlet section 5 of the cascade, and start to exert influence on the boundary layer flow at the thinner part of the front boundary layer. The cross-flow flow on the wall 2 suppresses the tendency of the fluid near the end wall 2 to collide with the suction side.

The first concave structure 201 is a concave structure, the depth of the depression is close to the thickness of the boundary layer near the wall, it does not invade the high-speed mainstream region, and only exerts an influence on the fluid in the boundary layer near the wall, does not affect the flow velocity of the mainstream, and does not generate additional shape resistance , which has significant advantages over the traditional upward convex structure.

The length of the first recessed structure 201, the first first recessed structure 201 is located 1.0d to 1.5d upstream of the cascade inlet section 5, and the most downstream first recessed structure 201 is located 0.2 to 1.5d upstream of the cascade outlet section 6 The position of 0.5 times the chord length c _x . The arrangement line 3 of the first recessed structures 201 on the end wall 2 is parallel to the central arc 4 of the cascade, and the arrangement of the first recessed structures 201 crosses the most convex part of the arrangement line 3 . Due to the development and thickening of the boundary layer near the wall at the downstream of the cascade channel, the channel vortex is already close to the suction side and gradually lifts away from the end wall 2, the first concave structure 201 of the end wall 2 downstream of the cascade channel will not be able to control the thickness. A large boundary layer and secondary flow eddies away from the end wall 2 exert influence and increase flow losses due to self-induced turbulence.

The shape of the wall surface of the first concave structure 201 is spherical or conical, and the shape of the first concave structure 201 can also be an oblong shape, such as the first concave structure 201 is an oblong shape, and the direction of the oblong depression is along the Align the direction of line 3.

The first recessed structures 201 are arranged on the end wall 2 of the cascade passage, the distance between the arrangement line 3 of the first recessed structures 201 and the middle arc line 4 is 0.5P-0.8P, and the arrangement line 3 of the first recessed structures 201 is more Close to the pressure side of the adjacent blade, as shown in FIG. 1 , the arrangement line 3 of the first concave structure 201 is closer to the blade pressure surface 102 of the upper blade body 1 .

The invention utilizes the concave structure on the blade suction surface and the end wall, which can significantly improve the flow of the cascade channel and improve the aerodynamic efficiency of the turbine.

In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", The orientation or positional relationship indicated by "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, rather than indicating or implying the referred device Or elements must have a certain orientation, be constructed and operate in a certain orientation, and thus should not be construed as limiting the application.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims (8)

1. A structure for improving aerodynamic efficiency of a low pressure turbine cascade, comprising: an end wall (2) and a blade body (1); the end wall (2) is a surface of a blade grid channel perpendicular to the blade body (1);

the end wall (2) is provided with a plurality of first concave structures (201), the first concave structures (201) are positioned between two adjacent blade bodies (1), the first concave structures (201) are used for enhancing the momentum exchange between the boundary layer flow and the outside main flow, enhancing the near-wall flow kinetic energy and changing the near-wall flow direction;

the blade body (1) is provided with a blade suction surface (101) and a blade pressure surface (102), the blade suction surface (101) is an outer convex surface of the blade body (1), and the blade pressure surface (102) is an inner concave surface of the blade body (1);

the blade suction surface (101) is provided with a plurality of second concave structures (1011), and the second concave structures (1011) are used for inhibiting flow separation on the blade suction surface (101) and avoiding generating separation vortex.

2. Structure for improving aerodynamic efficiency of a low pressure turbine cascade according to claim 1, characterized in that several of the first recess structures (201) are arranged along an alignment line (3), which alignment line (3) is parallel to the camber line (4) of the blade body (1).

3. The structure for improving aerodynamic efficiency of a low pressure turbine cascade according to claim 1, characterized in that the second recess structure (1011) is provided in plurality, the depth of the second recess is 0-6.0 mm;

every two second concave structures (1011) are a pair of V-shaped structures, and a plurality of V-shaped structures are formed on the suction surface (101) of the blade.

4. A structure for improving aerodynamic efficiency of a low pressure turbine cascade according to claim 1, characterized in that the second recess structure (1011) is arranged close to the most convex position of the blade body (1) and on a distance surface downstream of the most convex position 0.1-10 times the recess diameter d.

5. The structure for improving aerodynamic efficiency of a low pressure turbine cascade according to claim 1, characterized in that the ratio of the recess diameter d of the first recess structure (201) to the blade pitch P of the blade body (1) is 0.01-0.1;

the ratio of the recess depth h of the first recess structure (201) to the recess diameter d of the first recess structure (201) is 0.05-0.3.

6. The structure for improving aerodynamic efficiency of a low pressure turbine cascade according to claim 5, characterized in that the first recess structure (201) has an axial arrangement spacing s _x The ratio of the concave diameter d of the first concave structure (201) to the concave diameter d of the first concave structure is 1.1-1.5;

the distance between the central point of the first concave structure (201) on the arrangement line (3) and the cross section of the blade grid inlet is 1.0-1.5 d from the upstream;

the axial distance between the central points of the first concave structures (201) at the head and the tail on the arrangement line (3) is L=5-10 d, and the axial distance between the first concave structures (201) at the tail and the blade grid outlet section (6) is 0.25-0.5 times of chord length Cx.

7. The structure for improving aerodynamic efficiency of a low pressure turbine cascade according to claim 6, characterized in that the first concave structures (201) are arranged at positions of 0.5P-0.8P in the circumferential direction in the cascade channels, P being the pitch of the blades of the blade body (1), the first concave structures (201) being arranged closer to the adjacent blade pressure surfaces.

8. For increasing low pressure according to claim 1The aerodynamic efficiency structure of the turbine cascade is characterized in that, from upstream, the first one of the first concave structures (201) is located at a chord length c of 0.05-0.3 times upstream of the cascade inlet section (5) _x The most downstream first concave structure (201) is located at the upstream of the blade grid outlet section (6) by 0.2-0.5 times of the chord length c _x Is a position of (2);

d is the concave diameter of the first concave structure (201), and d is 1.0-50mm; c _x C is the length of the blade body (1) in the axial direction of the blade grid _x The length is 5-20 times the diameter d of the concave.

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