An adaptive jet device for an axial compressor endwall

Abstract

An end wall self-adaptive jet device of an axial flow compressor. It is installed on the outer surface of the casing corresponding to the position of the stator blade, which is a circular tapered pipe formed by sweeping along the center line, the center line is fitted by a Bezier curve, one end is an air inlet, the air inlet penetrates the casing behind the leading edge of the stator blade and closely adheres to the pressure surface of the stator blade, the other end is an air outlet, the air outlet penetrates the casing behind the middle of the axial chord length of the stator blade and is close to the suction surface of the stator blade. The effect of the application is that the pressure surface and the suction surface of the stator blade on the axial flow compressor are connected, the pressure difference between the air inlet and the air outlet forms a high-energy jet acting on the corner separation area, and the self-adaptive adjustment can be realized according to the change of the working condition of the axial flow compressor. Under suitable design parameters, it can effectively act on the corner flow field of the stator blade, reduce the range of corner separation, reduce the total pressure loss, improve the load of the stator blade, and improve the total pressure ratio and isentropic efficiency under small flow working condition.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of impeller machinery, and particularly relates to an end wall self-adaptive jet device of an axial flow compressor. BACKGROUND

[0002] With the development of aviation technology, the demand for high thrust-to-weight ratio engines is increasingly urgent, and improving the single-stage pressure ratio of the compressor and achieving higher stage load have become important solutions, but this will also lead to an increase in the adverse pressure gradient in the compressor blade passage, making the boundary layer more prone to separation. Among them, the adverse pressure gradient and the transverse pressure difference enhance the secondary flow in the flow passage, causing low-energy fluid to accumulate in the corner area and the suction surface trailing edge, thereby blocking the blade passage and causing severe corner separation, thereby reducing the efficiency and stable working range of the compressor.

[0003] Corner separation refers to the low-energy fluid backflow and accumulation phenomenon occurring in the corner area of the compressor suction surface-end wall, which severely restricts the development of high load of the compressor. In order to improve the performance of the compressor, corresponding flow control methods need to be used to effectively control the corner separation in the flow passage. At present, the flow control of corner separation mainly includes three-dimensional blade design, self-circulating casing treatment, wing knife, groove, plasma excitation, boundary layer suction and jet, etc. Among them, the implementation of active control needs to introduce energy from the outside, and passive control does not need to introduce energy, but achieves flow control by adding or changing structures, and these two ways have their own advantages and disadvantages. Researchers have never stopped studying corner separation, and the exploration of new flow control methods has never stopped. SUMMARY

[0004] In order to solve the above problems, the purpose of the present application is to provide an end wall self-adaptive jet device of an axial flow compressor.

[0005] In order to achieve the above purpose, the end wall self-adaptive jet device of the axial flow compressor provided by the present application comprises rotor blades, stator blades, a casing and a hub; a plurality of stator blades are arranged radially, with the blade top and the blade bottom being fixed on the casing and the hub respectively; a plurality of rotor blades are located in front of the stator blades; wherein the stator blade is an arc plate, the inner arc surface is the pressure surface, and the outer arc surface is the suction surface, the inner arc surface and the outer arc surface have two intersection lines in the axial direction, wherein the intersection line close to the inlet direction is the leading edge line, and the intersection line close to the outlet direction is the trailing edge line, the distance between the leading edge line and the trailing edge line is the chord length of the stator blade, the height direction of the stator blade is the span direction, the connecting line direction between the same parts of the two stator blades is the circumferential direction, and the direction perpendicular to the circumferential direction in the end wall plane is the axial direction; the inlet-outlet jet angle is the included angle between the inlet-outlet airflow direction and the axial direction; the inlet-outlet yaw angle is the included angle between the inlet-outlet airflow and the axial direction, wherein the yaw angle direction is the same as the rotation direction of the rotor blade, and the positive angle is obtained.

[0006] The end wall self-adaptive jet device is installed on the outer surface of the casing corresponding to the position of the stationary blade, which is a circular tapered pipe formed by sweeping along the center line, the center line is fitted by a Bezier curve, one end is an air inlet, the air inlet penetrates the casing behind the leading edge of the stationary blade and closely adheres to the pressure surface of the stationary blade, the other end is an air outlet, the air outlet penetrates the casing behind the middle of the axial chord length of the stationary blade and is close to the suction surface of the stationary blade.

[0007] The cross section of the circular tapered pipe where the air inlet and the air outlet are located is circular, and the interface with the casing is elliptical.

[0008] The center of the air inlet is located at 8% of the axial chord length of the stationary blade, and the center of the air outlet is located at 40%-50% of the axial chord length of the stationary blade.

[0009] The diameter of the circular cross section of the air inlet is 4mm, and the diameter of the circular cross section of the air outlet is 2.8mm, so the contraction ratio of the circular tapered pipe is 2; the inlet jet angle is 60°, the outlet jet angle is 30°; the inlet yaw angle is-15°, and the outlet yaw angle is 0°; the circumferential coverage ratio of the end wall self-adaptive jet device is 100%.

[0010] The end wall self-adaptive jet device of the axial flow compressor provided by the application has the beneficial technical effects as follows: the end wall self-adaptive jet device connects the pressure surface and the suction surface of the stationary blade of the axial flow compressor, forms a high-energy jet acting on the corner separation area through the pressure difference between the air inlet and the air outlet, and can realize self-adaptive adjustment according to the change of the working condition of the axial flow compressor. Under suitable design parameters (axial position, inlet and outlet area, inlet and outlet angle), the end wall self-adaptive jet device can effectively act on the corner flow field of the stationary blade, reduce the range of corner separation, reduce total pressure loss, improve the load of the stationary blade, and improve the total pressure ratio and isentropic efficiency under small flow working conditions. The end wall self-adaptive jet device has the advantages of simple structure, small volume, and strong flexibility, and can be optimized and designed according to the change of multiple parameters, and has better engineering application. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is a meridian plane schematic diagram of a single-stage transonic axial flow compressor.

[0012] Figure 2 It is a meridian plane schematic diagram of an axial flow compressor adopting the end wall self-adaptive jet device provided by the application.

[0013] Figure 3 It is a three-dimensional structure schematic diagram of an axial flow compressor adopting the end wall self-adaptive jet device provided by the application.

[0014] Figure 4 It is a local structure top view of an axial flow compressor adopting the end wall self-adaptive jet device provided by the application.

[0015] Figure 5 The 90% blade height section streamline diagram of the upper stator blade of the axial compressor without the end wall self-adapting jet device.

[0016] Figure 6 The 90% blade height section streamline diagram of the upper stator blade of the axial compressor with the end wall self-adapting jet device. DETAILED DESCRIPTION

[0017] The application will be described in detail below with reference to the drawings.

[0018] As shown in Figure 1 the axial compressor of the end wall self-adapting jet device provided by the application comprises blade 1, stator blade 2, casing 3 and hub 4; a plurality of stator blades 2 are arranged radially, and the top and bottom of the blade are fixed on the casing 3 and the hub 4 respectively; a plurality of rotor blades 1 are located in front of the stator blades 2; wherein the stator blade 2 is an arc plate, the inner arc surface is the pressure surface 11, and the outer arc surface is the suction surface 12; the inner arc surface 11 and the outer arc surface 12 have two intersection lines in the axial direction, wherein the intersection line close to the inlet direction is the leading edge line 5, and the intersection line close to the outlet direction is the trailing edge line 6; the distance between the leading edge line 5 and the trailing edge line 6 is the chord length of the stator blade 2; the height direction of the stator blade 2 is the span direction; the connecting line direction between the same parts of two stator blades 2 is the circumferential direction; the direction perpendicular to the circumferential direction in the end wall plane is the axial direction; the inlet-outlet jet angle is the included angle between the inlet-outlet airflow direction and the axial direction; the inlet-outlet yaw angle is the included angle between the inlet-outlet airflow and the axial direction, wherein the yaw angle direction is the same as the rotation direction of the rotor blade 1, and the positive angle is the same as the rotation direction of the rotor blade 1.

[0019] As shown in Figures 2 to 4 the end wall self-adapting jet device 7 is installed on the outer surface of the casing 3 corresponding to the position of the stator blade 2, which is a circular tapered pipe formed by sweeping along the center line, the center line is fitted by a Bezier curve, one end is the inlet 8, and the other end is the outlet 9; the inlet 8 penetrates the casing 3 behind the leading edge of the stator blade 2 and closely adheres to the pressure surface 11 of the stator blade 2; the outlet 9 penetrates the casing 3 behind the middle of the axial chord length of the stator blade 2 and is close to the suction surface 12 of the stator blade 2.

[0020] The cross section of the circular tapered pipe where the center of the inlet 8 and the outlet 9 is located is circular, and the intersection with the casing 3 is elliptical.

[0021] The center of the inlet 8 is located at 8% of the axial chord length of the stator blade 2, and the center of the outlet 9 is located at 40%-50% of the axial chord length of the stator blade 2.

[0022] The circular cross-section diameter of the air inlet 8 is 4 mm, and the circular cross-section diameter of the air outlet 9 is 2.8 mm, so that the contraction ratio of the circular converging pipe is 2; the inlet jet angle is 60°, the outlet jet angle is 30°; the inlet yaw angle is -15°, and the outlet yaw angle is 0°; and the circumferential coverage ratio of the end wall self-adaptive jet device 7 is 100%.

[0023] The working principle of the end wall self-adaptive jet device of the axial flow compressor provided by the application will be described as follows:

[0024] When the airflow flows through the stator blade 2 on the axial flow compressor, a high pressure area is formed at the position of the air inlet 8 of the end wall self-adaptive jet device 7, and the pressure at the position of the air outlet 9 is relatively low. Under the action of the above pressure difference, the gas sucked into the circular converging pipe from the air inlet 8 will form a jet and be discharged from the air outlet 9. The jet will act on the corner separation area at the suction surface 12 and the casing 3 to inhibit the backflow of the gas and blow away part of the low-energy fluid, thereby slowing down the corner separation.

[0025] In order to verify the effect of the application, the inventors carried out numerical simulation on a single-stage transonic axial flow compressor without using the end wall self-adaptive jet device and a single-stage transonic axial flow compressor using the end wall self-adaptive jet device provided by the application. The specific simulation parameters of the single-stage transonic axial flow compressor are as follows:

[0026]

[0027] As shown in Figure 5 , Figure 6 , by comparing the streamline diagrams of the 90% blade height cross sections of the stator blade of the axial flow compressor without using the end wall self-adaptive jet device and the stator blade of the axial flow compressor using the end wall self-adaptive jet device under near stall conditions, it is found that after using the end wall self-adaptive jet device 7, the separation vortex of the corner area of the suction surface 12 of the stator blade 2 is obviously reduced, indicating that the corner separation range is reduced, and the flow capacity of the flow passage is enhanced.

[0028] At the same time, using the end wall self-adaptive jet device 7 reduces the total pressure loss and increases the static pressure rise. Under near stall conditions, when the end wall self-adaptive jet device 7 is used, the total pressure ratio is increased by 0.46%, the isentropic efficiency is increased by 0.74%, and the comprehensive stability margin is increased by 0.75%.

[0029] It can be seen that the axial flow compressor using the end wall self-adaptive jet device 7 provided by the application can effectively control the corner separation, improve the flow passage blockage, reduce the total pressure loss, and improve the static pressure rise, which is beneficial to improving the performance and stability of the axial flow compressor.

Claims

1. An endwall adaptive jet device for an axial compressor, wherein the axial compressor includes moving blades (1), stationary blades (2), a casing (3), and a hub (4); multiple stationary blades (2) are arranged radially, with the blade tips and blade bases fixed to the casing (3) and hub (4), respectively; multiple moving blades (1) are located in front of the stationary blades (2); wherein the stationary blades (2) are arc-shaped plates, with the inner arc surface being the pressure surface (11) and the outer arc surface being the suction surface (12). 2) The inner arc surface (11) and the outer arc surface (12) have two lines of intersection in the axial direction. The line of intersection closer to the air intake direction is the leading edge line (5), and the line of intersection closer to the air outlet direction is the trailing edge line (6). The distance between the leading edge line (5) and the trailing edge line (6) is the chord length of the stationary blade (2). The height direction of the stationary blade (2) is the spanwise direction. The direction of the line connecting the same part of the two stationary blades (2) is the circumferential direction. The direction perpendicular to the circumferential direction in the end wall plane is the axial direction. Its features are: The endwall adaptive jet device (7) is installed on the outer surface of the casing (3) corresponding to the position of the stationary blade (2). It is a circular tapered pipe formed by sweeping along the center line. The center line is fitted by a Bezier curve. One end is the air inlet (8). The air inlet (8) passes through the casing (3) where the leading edge of the stationary blade (2) is located and is close to the pressure surface (11) of the stationary blade (2). The other end is the air outlet (9). The air outlet (9) passes through the casing (3) where the middle part of the axial chord of the stationary blade (2) is located and is close to the suction surface (12) of the stationary blade (2).

2. The endwall adaptive jet device for an axial compressor according to claim 1, characterized in that: The circular tapering pipes at the center of the air inlet (8) and air outlet (9) are both circular, and the interface formed with the casing (3) is elliptical.

3. The endwall adaptive jet device for an axial compressor according to claim 1, characterized in that: The center of the air inlet (8) is located at 8% of the axial chord length on the stationary blade (2), and the center of the air outlet (9) is located at 40%-50% of the axial chord length on the stationary blade (2).

4. The endwall adaptive jet device for an axial compressor according to claim 1, characterized in that: The diameter of the circular cross-section of the air inlet (8) is 4 mm, and the diameter of the circular cross-section of the air outlet (9) is 2.8 mm. Therefore, the shrinkage ratio of the circular tapering pipe is 2; the circumferential coverage ratio of the end-wall adaptive jet device (7) is 100%.

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