An oscillating suction device and flow control method for gap leakage flow control

Abstract

The present application relates to the technical field of flow control, in particular to an oscillating suction device for gap leakage flow control and a flow control method, comprising: a flow guide cover, a first blade, a driving assembly and a second blade, which are arranged in the airflow pipeline in sequence along the airflow direction. The device drives the second blade to rotate through the driving assembly, so that the overlapping area of the second blade and the first blade changes periodically and continuously, thereby the effective flow area in the airflow pipeline changes periodically and continuously, the airflow flow in the airflow pipeline oscillates, and then the non-steady oscillating suction is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of flow control, and in particular to an oscillating suction device for gap leakage flow control and a flow control method. Background Art

[0002] Axial compressor rotors and cantilevered stator blades are installed with a certain gap to prevent them from hitting the casing or hub during operation. Driven by the pressure difference across the blades, some fluid flows from the pressure side of the blades through the gap to the suction side, forming gap leakage flow. This can block the main flow, increase flow losses, and thus affect the overall aerodynamic performance of the compressor. Therefore, effectively controlling leakage flow is one of the key ways to reduce compressor flow losses, improve efficiency, and expand the stable operating range.

[0003] Boundary layer suction technology has received long-term attention from researchers due to its active and easily adjustable characteristics and its high efficiency in performance improvement. This technology has a good control effect on compressor gap leakage flow, and by shifting the starting position of the leakage vortex backward and reducing the leakage velocity, it plays a role in controlling the leakage flow and improving aerodynamic performance.

[0004] Unsteady-state flow control technology has become a research hotspot because it can achieve flow control efficiently and precisely. Pulsating air blowing and synthetic jets, as typical representatives of these technologies, have successfully controlled flow separation in turbomachinery, increased stall margin, improved flow fields, and enhanced device performance.

[0005] The research on unsteady control of boundary layer suction technology, which is also an active control technology, has gradually been used to control the separation of blade suction surface angle zones (see reference: Zhang H, Chen S. Pulsed suction control in a highly loaded compressor cascade with low suction flowrates[J]. Journal of Turbomachinery, 2021, 143(6): 061006.) and tip leakage flow (see reference: Zhang B, Mao X, Liu B, et al. Mechanisms of oscillating suction in controlling the tip leakageflow in a high-load compressor cascade[J]. Aerospace Science and Technology, 2023, 133: 108118.). The research results of this paper show that unsteady oscillating suction can achieve flow control at a very small time-averaged suction volume, and has more advantages than steady-state suction in a larger range of attack angles.

[0006] Unsteady-state oscillatory suction has great potential for flow control, and the unsteady nature of leakage flow also suggests that unsteady-state flow control technology is a reasonable approach to performance improvement. Achieving periodic, continuous oscillations of the suction airflow is a key challenge in oscillatory suction. Existing devices typically use solenoid valves to control the opening and closing of valves, thereby achieving pulsed oscillations of the airflow. However, the changes in suction volume are pulsed and have a long response time, making it impossible to achieve high-frequency, continuous, and regular functional changes (such as sine or cosine functions). Consequently, existing suction devices are unable to achieve high-frequency, continuous flow oscillations.

[0007] Therefore, it is necessary to provide an oscillating suction device and a flow control method for gap leakage flow control to solve the above problems. Summary of the Invention

[0008] The present invention provides an oscillating suction device and a flow control method for gap leakage flow control. By driving the second blade to rotate, the overlapping area of ​​the second blade and the first blade is periodically and continuously changed to change the flow area of ​​the airflow in the airflow duct, so as to solve the problem that the existing device controls the opening and closing of the valve through the solenoid valve to achieve pulse oscillation of the airflow, but the change of the suction amount is pulsed and the response time is long, and it is impossible to achieve high-frequency continuous regular function change.

[0009] The present invention provides an oscillating suction device for gap leakage flow control, which adopts the following technical solution:

[0010] The deflector is concentrically arranged inside the airflow duct to guide the airflow evenly;

[0011] A plurality of first blades are evenly distributed on the outer periphery of the air guide cover, and one end of the first blades facing away from the air guide cover is fixed to the inner wall of the air flow duct;

[0012] A driving assembly is arranged on a side of the guide surface away from the guide cover;

[0013] and a plurality of second blades uniformly arranged on the periphery of the rotating shaft, the rotating shaft being connected to the output end of the driving assembly, with an axial gap between the second blades and the first blades;

[0014] The driving assembly is used to drive the second blade to rotate, so that the overlapping area of ​​the second blade and the first blade changes periodically and continuously, so as to change the flow area of ​​the airflow in the airflow duct.

[0015] Preferably, the first blades are in the shape of an annular fan, and the central angle corresponding to each first blade is equal to the central angle corresponding to the bladeless area between the two first blades.

[0016] Preferably, the contour of the outer periphery of the second blade is a circular arc segment, and the contour between every two second blades is a periodic cosine curve segment.

[0017] Preferably, the central angle corresponding to the arc segment is equal to the central angle corresponding to the cosine curve segment, and the central angle corresponding to the cosine curve segment is equal to the central angle corresponding to the bladeless area between the two first blades.

[0018] Preferably, the difference between the radius corresponding to the second blade arc segment and the radius corresponding to the trough point of the cosine curve segment is 2e, 0.1R2≤2e≤(R2-R3), where R2 represents the radius corresponding to the second blade arc segment, and R3 represents the radius corresponding to the side of the air guide cover away from the guide surface (that is, the radius of the ground serving as the air guide cover in this embodiment).

[0019] Preferably, the difference between the radius corresponding to the second blade arc segment and the radius corresponding to the trough point of the cosine curve segment is 75% of (R2-R3).

[0020] Preferably, the radial spacing between the outer periphery of the second blade and the inner wall of the airflow duct is: R1-R2, and 0.01R2≤(R1-R2)≤0.1R2, wherein R1 represents the inner diameter of the airflow duct, and R2 represents the radius corresponding to the arc segment of the second blade.

[0021] Preferably, there is an axial gap s between the second blade and the first blade, and 0.05 (h s +h r )≤s≤0.5(h s+h r ), where h s represents the thickness of the first blade; h r Indicates the thickness of the second blade.

[0022] Preferably, the drive assembly comprises:

[0023] The support sleeve is concentrically arranged at the center of the airflow duct, with a space for mounting the second blade left between one end of the support sleeve and the air guide cover;

[0024] and a motor, which is arranged in the supporting sleeve and has an output shaft connected to the rotating shaft of the second blade.

[0025] Preferably, the guide surface of the air guide cover is one of a hemispherical surface, a conical surface or a rotating paraboloid, and the radius of the air guide cover is 10% to 70% of the radius of the air flow duct.

[0026] A flow control method for an oscillating suction device of the present invention comprises:

[0027] By adjusting the rotation speed of the second blade, the oscillation frequency of the suction amount of the oscillating suction device of the present invention is controlled;

[0028] By adjusting the pressure difference between the upstream and downstream of the oscillating suction device of the present invention, the amplitude of the suction amount of the oscillating suction device is controlled.

[0029] The beneficial effects of the present invention are:

[0030] By arranging the first blade and the second blade in the airflow duct, the driving component drives the second blade to rotate, so that the overlapping area of ​​the second blade and the first blade can change periodically and continuously, so that the effective flow area in the duct changes periodically and continuously, thereby causing the airflow flow in the airflow duct to oscillate, thereby realizing unsteady oscillating suction; providing a research basis for subsequent improvement of the aerodynamic performance and stable working margin of the compressor, as well as the gap leakage flow control technology of aircraft engines and gas turbine compressors. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 Schematic diagram of the overall structure of an embodiment of an oscillating suction device for gap leakage flow control according to the present invention;

[0033] Figure 2 A schematic structural diagram of an oscillating suction device for controlling gap leakage flow according to the present invention;

[0034] Figure 3 is a schematic structural diagram of a first blade in an embodiment of the present invention;

[0035] Figure 4 for Figure 1 Left view (from upstream to downstream);

[0036] Figure 5 is a schematic structural diagram of the second blade in an embodiment of the present invention;

[0037] Figure 6 for Figure 1 Right view (from downstream to upstream);

[0038] Figure 7 for Figure 6 KK cross-sectional view;

[0039] Figure 8 for Figure 7 AA section view;

[0040] Figure 9 for Figure 7 BB cross-sectional view;

[0041] Figure 10 for Figure 7 CC cross-sectional view;

[0042] Figure 11 is a graph showing flow rate-time variation at different rotation speeds of the second blade in the embodiment;

[0043] Figure 12 is a graph showing the relationship between the amplitude and frequency of the flow rate when the rotation speed of the second blade is different in the embodiment;

[0044] Figure 13 The graph of flow rate-time variation when the inlet and outlet pressure differences are different in the embodiment;

[0045] Figure 14 Graph showing the relationship between the amplitude and frequency of the flow rate when the inlet and outlet pressure differences are different in the embodiment;

[0046] In the figure: 1. air flow duct; 2. air guide cover; 3. first blade; 4. second blade; 5. support sleeve; 6. rotating shaft; 7. cosine curve segment. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] An embodiment of an oscillating suction device for gap leakage flow control of the present invention is as follows Figure 2 As shown, the oscillating suction device of the present invention is installed in an airflow duct with gap leakage flow, and oscillating suction is achieved by periodic changes in the flow area of ​​the airflow duct, thereby achieving the purpose of controlling gap leakage flow and reducing related flow losses. Specifically, the airflow duct is cylindrical, such as Figure 6 As shown, the inner wall radius of the airflow duct is R1, as shown in Figure 7 As shown, the thickness of the pipe wall of the air flow pipe is h1. In this embodiment, R1 is 41 mm and h1 is 5 mm. Figure 2 The air inlet of the air flow pipeline is connected to the suction collecting chamber of the gap leakage flow; the air outlet of the suction pipeline is connected to the vacuum pump.

[0049] Specifically, such as Figure 1 As shown, the oscillating suction device of the present invention comprises: a guide cover 2, a plurality of first blades 3, a driving assembly and a plurality of second blades 4; Figures 7 to 10 As shown, the air guide 2, the first blade 3, and the second blade 4 of the oscillating suction device coincide with the axis of the airflow duct 1 and are arranged in sequence along the airflow direction. The air guide 2 is concentrically arranged inside the airflow duct 1. It should be noted that, considering the unevenness of the incoming airflow in the oscillating suction device, the air guide 2 is arranged upstream of the first blade 3, so that the airflow can flow out more evenly from the bladeless area between the two adjacent first blades 3 and the bladeless area between the two adjacent second blades 4 in sequence, so as to achieve uniform guidance of the incoming flow; multiple first blades 3 are evenly distributed on the outer periphery of the air guide 2, and the end of the first blade 3 facing away from the air guide 2 is fixed to the inner wall of the airflow duct 1; the drive assembly is arranged on the side of the guide surface away from the air guide 2; multiple second blades 4 are evenly distributed on the outer periphery of the rotating shaft 6, the rotating shaft 6 is connected to the output end of the drive assembly, and there is an axial gap between the second blade 4 and the first blade 3; wherein the drive assembly is used to drive the second blade 4 to rotate, so that the overlapping area of ​​the second blade 4 and the first blade 3 changes periodically and continuously to change the flow area of ​​the airflow in the airflow duct 1.

[0050] Specifically, the first blades 3 are in the shape of an annular fan, and the central angle corresponding to each first blade 3 is equal to the central angle corresponding to the bladeless area between the two first blades 3. Specifically, Figure 3 and Figure 8 As shown, in this embodiment, the central angle of the first blade 3 is 45°, that is, there are 4 first blades in the stationary disk; the thickness of the first blade is h s In this embodiment, h s The radius of the tip of the first blade 3 (ie, the inner diameter of the airflow duct 1) is R1, and the radius of the root of the first blade (ie, the radius of the bottom of the air guide cover 2) is R3. In this embodiment, R1 is 41 mm and R3 is 20 mm.

[0051] Specifically, such as Figure 5 and Figure 6 As shown, the second blade 4 is formed by cutting out several special shapes from a disc. The blade profile of each second blade 4 is composed of a cosine curve and a circular arc. Specifically, Figure 5 The arc segments and cosine curve segments 7 of the four second blades 4 shown are connected together (i.e., a contour line composed of a complete cycle of cosine curves and arc lines alternately and evenly connected), that is, the contour of the outer periphery of each second blade 4 is an arc segment, and the contour between every two second blades 4 is a cycle of cosine curve segments 7, the central angle corresponding to the arc segment is equal to the central angle corresponding to the cosine curve segment 7, and the central angle corresponding to the cosine curve segment 7 is equal to the central angle corresponding to the bladeless area between the two first blades 3; in this embodiment, the central angle corresponding to the cosine curve segment 7 is 45°; the thickness of the second blade 4 is h r In this embodiment, h r is 5mm; the maximum radius of the second blade 4 is R2, and in this embodiment R2 is 40mm; the difference between the maximum radius and the minimum radius in the blade profile of the second blade 4 is 2e (that is, the difference between the radius corresponding to the arc segment of the second blade 4 and the radius corresponding to the trough point of the cosine curve segment 7 is 2e), that is, the minimum radius of the second blade 4 is (R2-2e); in order to ensure the effective oscillation of the suction airflow, 2e cannot be too small, otherwise the oscillation amplitude will be too small. Therefore, in this embodiment, the radius difference 2e satisfies: 0.1R2≤2e≤(R2-R3). In this embodiment, 2e is 15mm, which is 75% of (R2-R3).

[0052] Specifically, such as Figure 6 and Figure 7As shown, in order to avoid scraping and damage during rotation, the radial spacing between the outer periphery of the second blade 4 and the inner wall of the airflow duct 1 is set to: R1-R2, and the axial gap between the first blade 3 and the second blade 4 is s; in order to reduce the flow loss in the airflow duct 1 and improve the response accuracy of the oscillating airflow flow to the flow area, the radial spacing and the axial gap should be as small as possible; considering the actual processing accuracy and error factors, in this embodiment, the radial spacing R1-R2 meets the condition: 0.01R2≤(R1-R2)≤0.1R2, and in this embodiment (R1-R2) is 0.025R2; the axial gap s meets the condition: 0.05(h s +h r )≤s≤0.5(h s +h r ), in this embodiment, s is taken as 0.2(h s +h r ), where h s represents the thickness of the first blade 3; h r Indicates the thickness of the second blade 4 .

[0053] Specifically, such as Figures 5 to 7 As shown, the driving assembly includes: a support sleeve 5 and a motor, the support sleeve 5 is concentrically arranged at the center of the airflow duct 1, and a space for installing the second blade 4 is left between one end of the support sleeve 5 and the air guide cover 2; the motor is fixedly arranged in the support sleeve 5, and its output shaft is connected to the rotating shaft 6 of the second blade 4, and the second blade 4 is driven by the motor to rotate at a constant speed of n; in this way, during the rotation of the second blade 4, the overlapping area of ​​the second blade 4 and the first blade 3 changes periodically and continuously, so that the effective flow area of ​​the airflow in the airflow duct 1 changes, and further, the airflow flow in the airflow duct 1 will oscillate with the change of the effective flow area in the airflow duct 1, thereby realizing unsteady oscillation suction.

[0054] In this embodiment, the support sleeve 5 is tightly attached to the right side of the second blade 4, the rotating shaft 6 is fixedly connected to the right side of the second blade 3, and the motor drives the second blade 4 to rotate at a uniform speed through the rotating shaft 6, thereby finally realizing a stable and regular periodic continuous oscillation of the suction airflow; the motor and other accessories connected to the rotating shaft 6 are fixed in the support sleeve 5 through the bearing seat, which can ensure the stable and safe operation of the motor without affecting the suction airflow; specifically, the support sleeve 5 is cylindrical, and the outer diameter of the support sleeve 5 is equal to the radius (R3) of the bottom surface of the air guide cover. In this embodiment, the outer diameter of the support sleeve 5 is 20mm; the wall thickness of the support sleeve 5 is h2, and in this embodiment, h2 is 5mm; the radius of the rotating shaft 6 is R4, which is selected according to the size of the motor output shaft, and the radius should be smaller than the inner diameter of the support sleeve (R3-h2). In this embodiment, R4 is 6mm; the length of the rotating shaft 6 can be determined according to the requirements of the motor output shaft and the connecting element.

[0055] It should be noted that, during the relative rotation of the first blade 3 and the second blade 4 of the oscillating suction device, the effective flow area of ​​the airflow duct 1 changes periodically and continuously, under the premise of ensuring that the pressure difference between the upstream and downstream of the oscillating suction device remains unchanged, that is, Figure 2 As shown, when the vacuum pump provides a stable vacuum degree, the suction airflow presents a periodic and continuous change, and the change form is a sine (cosine) function; specifically, the relationship between the change of the effective flow area in the airflow duct 1 with time is:

[0056]

[0057] in,

[0058]

[0059] a=e(R2-e) (3)

[0060]

[0061] Wherein, (A0+a) represents the time-averaged value of the effective flow area of ​​the oscillating suction device (i.e., the average value of the effective flow area of ​​the oscillating suction device over a period of time); the time-averaged value of the effective flow area can be adjusted by changing the maximum radius of the second blade 4 (the radius R2 corresponding to the arc segment of the second blade 4) and the difference 2e between the maximum radius and the minimum radius of the second blade 4, thereby adjusting the time-averaged value of the suction volume;

[0062] a represents the amplitude of change of the effective flow area, so the oscillation amplitude of the suction volume is controlled by changing the maximum radius and the minimum radius of the profile of the second blade 4 from the center, or by changing the pressure difference between the upstream and downstream of the oscillating suction device;

[0063] f represents the frequency of change of the effective flow area, so the oscillation frequency of the suction volume is controlled by adjusting the rotation speed n of the second blade 4 and the angle corresponding to the cosine curve segment 7 in the second blade 4.

[0064] t represents time;

[0065] represents the initial phase;

[0066] θ represents the angle corresponding to the arc segment of the second blade 4;

[0067] R1 represents the inner diameter of the airflow duct;

[0068] R2 represents the radius corresponding to the arc segment of the second blade 4;

[0069] Specifically, such as Figures 1 to 4As shown, the guide surface of the air guide cover 2 of this embodiment is: one of a hemispherical surface, a conical surface or a rotating paraboloid. The radius of the bottom surface of the air guide cover 2 is equal to the radius of the root of the first blade 3 (i.e., R3). The selection of the radius of the air guide cover 2 should fully consider the flow area and the guide effect. The radius corresponding to the bottom surface of the air guide cover 2 is defined as 10% to 70% of the radius of the airflow duct 1; specifically, the air guide cover 2 in this embodiment is hemispherical, and its radius is 20 mm, that is, the radius of the air guide cover 2 is 48.78% of the radius of the airflow duct.

[0070] A flow control method for an oscillating suction device of the present invention comprises:

[0071] By adjusting the rotation speed of the second blade 4, the oscillation frequency of the suction amount of the oscillating suction device of the present invention is controlled;

[0072] By adjusting the pressure difference between the upstream and downstream of the oscillating suction device of the present invention, the amplitude of the suction amount of the oscillating suction device is controlled.

[0073] How it works

[0074] The second blade 4 is driven to rotate at a constant speed by the rotation of the motor, so that the overlapping position and area of ​​the first blade 3 and the rotating blade 4 undergo periodic sinusoidal function changes, so that the effective flow area in the airflow duct 1 undergoes periodic sinusoidal function type continuous changes. Furthermore, as the flow area of ​​the airflow duct 1 changes, the airflow flow rate will oscillate in the sinusoidal function type, thereby realizing oscillatory suction of the gap leakage flow.

[0075] In order to verify the effect of the present invention, a numerical simulation of the oscillating suction device of the present invention was carried out. The specific implementation process is as follows:

[0076] (1) Figure 1 As shown, the oscillating suction device is modeled using three-dimensional simulation software (NX UG), where the guide cover 2 and the first blade 3 are located in the static domain, and the axial length of the static domain is 100 mm; the second blade 4 and the support sleeve 5 are located in the rotating domain, and the axial length of the rotating domain is 100 mm.

[0077] (2) Use ANSYS Meshing to mesh the computational domain and generate an unstructured grid.

[0078] (3) The three-dimensional steady-state Reynolds-averaged Navier–Stokes equations were solved by ANSYS CFX based on the finite volume method and the SST k-ω turbulence model. The convection term, turbulence term and time term in the equation were discretized using a high-resolution scheme. The rotation speed of the second blade 4 was set to 300 r / min, 600 r / min and 900 r / min respectively in the calculation. The static pressures at the inlet (upstream of the first blade) and outlet (downstream of the second blade) were given, and the pressure differences were set to 20,000 Pa, 30,000 Pa and 40,000 Pa respectively.

[0079] (4) Obtain the results of numerical simulation and perform data processing.

[0080] like Figure 11 and Figure 13 As shown, the oscillating suction device and flow control method for gap leakage flow control in this embodiment can successfully achieve periodic continuous (sinusoidal function) oscillation of the flow rate through the periodic change of the overlapping area of ​​the second blade 4 and the first blade 3.

[0081] like Figure 11 and Figure 12 As shown, changing the rotation speed of the second blade 4 can change the oscillation frequency of the suction amount, and the relationship between the oscillation frequency and the rotation speed of the second blade satisfies the formula (4) in the embodiment of the present invention; in this embodiment, when the upstream and downstream pressure difference of the oscillating suction device is fixed at 20000Pa and the rotation speed of the second blade is 300r / min, 600r / min and 900r / min respectively, the average value and amplitude of the flow rate remain unchanged, the average value of the flow rate is 0.125kg / s, and the amplitude is 0.054kg / s; the oscillation frequency of the flow rate is 20Hz, 40Hz and 60Hz respectively.

[0082] like Figure 13 and Figure 14 As shown, changing the upstream and downstream pressure difference of an oscillating suction device and a flow control method for gap leakage flow control in this embodiment can change the amplitude of the suction amount; in this embodiment, when the rotation speed of the second blade 4 is fixed at 600r / min and the upstream and downstream pressure differences of the oscillating suction device are 20000Pa, 30000Pa and 40000Pa respectively, the average values ​​of the flow rate are 0.125kg / s, 0.145kg / s and 0.157kg / s respectively, the amplitudes of the flow rate are 0.054kg / s, 0.062kg / s and 0.065kg / s respectively, and the oscillation frequency of the flow rate is 40Hz.

[0083] At this point, the oscillating suction device provided by the present invention realizes the oscillating suction of the gap leakage flow, that is, it realizes the unsteady flow control of the low-energy fluid in the flow field; the unsteady oscillation of the suction airflow is utilized to enhance the energy exchange between the low-energy fluid and the mainstream in the flow field, and at the same time, the large-scale concentrated vortex system in the flow field is discretized into a more active vortex structure with a reduced scale. Therefore, the present invention has a better flow control effect than traditional steady-state suction, and provides a possible technical solution for improving the aerodynamic performance of the engine compression system.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An oscillating suction device for gap leakage flow control, characterized in that: include: A flow guide cover (2) is concentrically arranged inside the airflow duct (1) and is used to guide the airflow uniformly; A plurality of first blades (3) are evenly distributed on the outer periphery of the air guide cover (2), and one end of the first blades (3) facing away from the air guide cover (2) is fixed to the inner wall of the air flow duct (1); A drive assembly is arranged on a side of the guide surface away from the guide cover (2); and a plurality of second blades (4) uniformly arranged on the periphery of a rotating shaft (6), the rotating shaft (6) being connected to the output end of the driving assembly, and an axial gap being provided between the second blades (4) and the first blades (3); the contour of the periphery of the second blades (4) being an arc segment, and the contour between each two second blades (4) being a periodic cosine curve segment (7); the central angle corresponding to the arc segment being equal to the central angle corresponding to the cosine curve segment (7), and the central angle corresponding to the cosine curve segment (7) being equal to the central angle corresponding to the bladeless region between the two first blades (3); the difference between the radius corresponding to the arc segment of the second blade (4) and the radius corresponding to the trough point of the cosine curve segment (7) being 2 , ,in, represents the radius corresponding to the arc segment of the second blade (4), represents the radius of the side of the guide cover (2) away from the guide surface; The driving assembly is used to drive the second blade (4) to rotate, so that the overlapping area of ​​the second blade (4) and the first blade (3) changes periodically and continuously, thereby changing the flow area of ​​the airflow in the airflow duct (1); and the radius of the air guide cover (2) is 10% to 70% of the radius of the airflow duct (1); the radial distance between the outer periphery of the second blade (4) and the inner wall of the airflow duct (1) is: ,and ,in, represents the inner diameter of the air flow duct (1), represents the radius corresponding to the arc segment of the second blade (4); there is an axial gap between the second blade (4) and the first blade (3) of ,and ,in, represents the thickness of the first blade (3); Indicates the thickness of the second blade (4).

2. An oscillating suction device for gap leakage flow control according to claim 1, characterized in that: The drive components include: The support sleeve (5) is concentrically arranged at the center of the airflow duct (1), and a space for installing the second blade (4) is left between one end of the support sleeve and the air guide cover (2); and a motor, which is arranged in the support sleeve (5), and whose output shaft is connected to the rotating shaft (6) of the second blade (4).

3. An oscillating suction device for gap leakage flow control according to claim 1, characterized in that: The flow guide surface of the flow guide cover (2) is one of a hemispherical surface, a conical surface or a rotational paraboloid.

4. A flow control method for an oscillating suction device, characterized in that: include: By adjusting the rotation speed of the second blade (4), the oscillation frequency of the suction amount of the oscillating suction device according to any one of claims 1 to 3 is controlled; The amplitude of the suction amount of the oscillating suction device is controlled by adjusting the pressure difference between the upstream and downstream of the oscillating suction device according to any one of claims 1 to 3.

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