Air inlet channel experiment device capable of adjusting deflation flow and design method thereof

Abstract

The invention discloses an air inlet experiment device capable of adjusting deflation flow and a design method of the air inlet experiment device. By properly simplifying the hypersonic-speed air inlet channel with the large internal contraction ratio, the length of the air inlet channel can be remarkably reduced under the condition of similar effects, and meanwhile, a sliding type deflation flow adjusting device is applied to the air inlet channel to continuously adjust deflation flow. The air inlet duct experiment device is small in size, simple in structure, high in reliability and small in aerodynamic force influence, hypersonic speed air inlet duct experiments can be carried out in a wind tunnel with the small size and the low Mach number, flow control of various movement modes and various speeds is achieved at the same time, and the experiment efficiency is improved. And a reliable experimental device is provided for realizing wide-speed-domain flight in a large-internal-contraction-ratio fixed-geometry air inlet channel.

Description

Technical Field

[0001] The invention relates to the field of hypersonic inlet aerodynamic experiments, in particular to an inlet experimental device capable of adjusting exhaust air flow rate and a design method thereof. Background Art

[0002] As an important boosting system of hypersonic aircraft, the air inlet mainly decelerates and boosts the oncoming high-speed airflow through the shock wave system, and at the same time shoulders important tasks such as meeting the engine flow demand and rationally organizing the forebody flow. Studies have shown that improving the compression capacity of the air inlet is of great significance for improving the working efficiency of the propulsion system and reducing the weight of the propulsion system. However, the improvement of the air inlet compression capacity mainly depends on the increase of the contraction ratio in the air inlet, which brings two problems. First, the air inlet is difficult to start at low Mach numbers, which will limit the wide-speed flight capability of the aircraft; second, the shock wave / boundary layer interference phenomenon in the air inlet tube is prominent, which makes the air inlet flow congested and brings local high-temperature heat flow, high-pressure pulsation, etc.

[0003] To this end, in order to address the adverse effects of high compression on the inlet duct, several slots or holes are often set in the inner contraction section, and the high pressure of the compressed air flow is used to drive the excess flow or low-energy fluid out of the inlet duct, thereby widening the stable working boundary of the inlet duct and effectively suppressing separation. This method is called "bleeding". This method has a simple and reliable structure and is very effective. As a common flow control method for the inlet duct, it has been widely used in various types of inlets. However, since the high-pressure gas compressed by the inlet duct is often bleeded, the bleed resistance is large, and the bleed flow under the flight limit state can often reach more than 10% of the total captured flow, further aggravating the problem of insufficient thrust of the propulsion system. Therefore, it is necessary to take into account the aerodynamic thrust and resistance of the aircraft while meeting the stable working requirements of the inlet duct as much as possible.

[0004] In order to solve this problem, the method of adjusting the bleed flow rate is usually adopted to make the bleed flow rate of the inlet duct large at low Mach numbers to obtain better aerodynamic performance, reduce the bleed flow rate in the cruising state, obtain greater thrust, and ensure that the performance of the propulsion system does not decrease while widening the working range of the inlet duct. At the same time, due to the limitation of the size of the wind tunnel, the long forebody of the hypersonic aircraft brings great difficulties to the experiment, and it is often necessary to simplify the inlet duct, which not only makes it impossible to truly simulate the flight state, but also makes the space available for the arrangement of the flow adjustment device more cramped; the high temperature and strong aerodynamic force of the high-speed incoming flow in the experiment also have high requirements on the reliability of the actuator; if you want to achieve regulation in the full flight state, the continuous stepless adjustment of the flow control device is also one of the difficulties.

[0005] Therefore, a new technical solution is needed to solve the above technical problems. Summary of the invention

[0006] Purpose of the invention: To solve the above problems, the present invention provides an inlet experimental device with adjustable bleed air flow rate and a design method thereof. By reasonably simplifying a hypersonic inlet with a large internal contraction ratio, the length of the inlet can be significantly reduced while achieving similar effects. At the same time, a sliding bleed air flow regulating device is adopted to continuously adjust the bleed air flow rate. The device of the present invention has small size, simple structure, strong reliability, and little influence by aerodynamic forces. It can carry out hypersonic inlet experiments in wind tunnels with smaller size and lower Mach number. At the same time, it can carry out flow control in multiple motion modes and multiple speeds. It has certain versatility and provides a reliable device for wide-speed range flight experiments of fixed-geometry inlets with large internal contraction ratios.

[0007] Technical solution: An air intake test device capable of adjusting exhaust flow, characterized in that it comprises: an air intake system, an adjustment system;

[0008] The air inlet system includes a compression surface, a lip cover located above the compression surface, and side panels located on both sides of the compression surface, and the lip cover, the compression surface and the side panels enclose an inner channel of the air inlet, a plurality of mutually independent deflation cavities arranged in sequence from front to back are provided below the compression surface, and a deflation groove is provided on the compression surface to connect the deflation cavity with the inner channel of the air inlet, and a deflation cavity outlet is provided at the bottom of each deflation cavity;

[0009] The adjustment system includes a sliding plate, a driving device connected to the sliding plate, a slider connected to the sliding plate, and a slide rail for the slider to move forward and backward; the sliding plate is arranged close to the outlet of the deflation chamber, and has a plurality of openings and baffles located between two adjacent openings. The forward and backward movement of the sliding plate causes the openings and / or the baffles to be located below the outlet of the deflation chamber, thereby changing the discharge area of ​​the outlet of the deflation chamber.

[0010] Furthermore, the front section of the compression surface is an isosceles pentagon, the longer base of the isosceles pentagon is the front edge of the compression surface, and the shorter base is connected to the inner channel of the air inlet duct. The front section of the compression surface is straight, and the compression surface gradually bends after entering the inner channel and returns to straightness after the throat.

[0011] Furthermore, a serrated transition zone having the same width as the front edge of the compression surface is arranged near the front edge of the compression surface, so that the boundary layer transitions and thickens, except for the serrated transition zone.

[0012] Furthermore, the slide rails have two parallel rails extending from front to back, and the sliders are distributed on the two slide rails, and the sliders are located at the bottom of both sides of the sliding plate.

[0013] Furthermore, the air release groove is located on the compression surface from the entrance to the throat of the air inlet channel.

[0014] Furthermore, a plurality of the venting grooves are grouped into one group, the width of the venting grooves in each group is equal to the interval between the grooves, and the interval between the groups is greater than the width of one venting groove.

[0015] Furthermore, the outlet area of ​​the venting cavity is equal to the sum of the areas of all venting grooves in the corresponding group.

[0016] Furthermore, the side panels are connected to both sides of the compression plate, and optical glass is arranged in the side panels.

[0017] Furthermore, the driving device is connected to the sliding plate, and drives the sliding plate to move forward and backward along the slide rails on both sides with the help of the sliding blocks.

[0018] A design method for an air intake duct experimental device capable of adjusting exhaust air flow rate comprises the following steps:

[0019] Step 1, determine the aerodynamic performance index requirements of the air inlet, design the configuration of the air inlet accordingly, and obtain the deflection angle δ1 of the air inlet compression surface and the deflection angle δ2 of the lip mask;

[0020] Step 2: Based on the inlet duct configuration obtained in step 1, the last stage compression surface to the isolation section is intercepted, and the compression surface deflection angle δ1 is rotated to make the front end of the compression surface horizontal, and a simplified inlet duct configuration is obtained, and its internal contraction ratio is

[0021] ICR=H in / H throat

[0022] Where ICR is the internal contraction ratio, H in is the inlet entrance height, H throat is the inlet throat height, and the internal contraction ratio of the simplified inlet configuration is greater than 2.5;

[0023] Step 3: Based on the simplified air inlet configuration obtained in step 2, the front end of the compression surface is an isosceles pentagon, the longer bottom side is the leading edge of the model, and the length of the longer bottom side is greater than the width of the air inlet entrance;

[0024] Step 4: Arrange a zigzag transition zone at the front end of the compression surface. The length of the transition zone is equivalent to the front edge of the model. The rear end of the transition zone is L away from the inlet entrance. d ≥100mm;

[0025] Step 5, the sawtooth of the transition belt protrudes from the plane, and the sawtooth shape is an isosceles right triangle;

[0026] Step 6: Based on the simplified inlet duct configuration obtained in step 5, the airflow deflection angle δ3 is calculated according to the compression surface deflection angle δ1 and the lip mask deflection angle δ2, and the following is obtained:

[0027] δ3=δ1+δ2

[0028] According to the calculation formula of the shock angle β of the oblique shock wave

[0029]

[0030] The incident position of the oblique shock wave is obtained, where M1 is the incoming flow Mach number, and multiple air release slots are arranged in front and behind the incident position as the center;

[0031] Step 7: To avoid air cross-talk, several air release grooves on the compression surface are divided into a group, the width of the air release grooves in each group is equal to the interval between the grooves, and the interval between the groups is greater than the width of one air release groove;

[0032] Step 8, the deflation cavities are vertically recessed from the bottom surface of the deflation grooves according to the groups, each deflation cavity corresponds to a group of deflation grooves, the outlet area of ​​the deflation cavity is equal to the sum of the areas of all the deflation grooves in the corresponding group, and the outlets of the deflation cavities are all in the same plane;

[0033] Step 9, the sliding plate is placed close to the deflation cavity, and a plurality of openings and baffles are provided on the sliding plate. The sliding plate moves forward and backward so that the openings and / or baffles are located below the outlet of the deflation cavity, thereby changing the discharge area of ​​the outlet of the deflation cavity;

[0034] Step 10: The driving device is placed in the center of the front part of the bracket, and drives the sliding plate to move forward and backward along the slide rails on both sides with the help of the slider;

[0035] Step 11: Design the side panels, bottom panel and bracket according to the actual space and installation requirements of the wind tunnel.

[0036] Beneficial effects: The present invention provides an inlet experimental device with adjustable exhaust flow rate, which has small size, simple structure, strong reliability, and little influence of aerodynamic force. It can carry out hypersonic inlet experiments in wind tunnels with smaller size and lower Mach number, and can carry out flow control in multiple motion modes and multiple speeds. It has certain versatility and provides a reliable device for wide-speed range flight experiments of large internal contraction ratio constant geometry inlets.

[0037] The present invention provides a design method for an air inlet experimental device with adjustable bleed air flow. By reasonably simplifying a hypersonic air inlet with a large internal contraction ratio, the length of the air inlet can be significantly reduced while achieving similar effects. At the same time, a sliding bleed air flow regulating device is used to continuously adjust the bleed air flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the external three-dimensional structure of the air intake duct of the present invention;

[0039] Figure 2 is a simplified schematic diagram of the air intake duct of the present invention;

[0040] Figure 3is a schematic cross-sectional view of an air intake duct according to the present invention;

[0041] Figure 4 is a top view of the air inlet of the present invention;

[0042] Figure 5 is the inlet Mach number distribution when the incoming flow Mach number is 3.8 in the embodiment of the present invention;

[0043] Figure 6 It is a Mach number cloud diagram when the incoming flow Mach number is 3.8 in the embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention is further explained below in conjunction with the accompanying drawings and specific implementation methods.

[0045] The present invention discloses an air intake duct experimental device capable of adjusting the exhaust air flow rate and a design method thereof. The detailed implementation steps of the design of the embodiment of the method of the present invention are described below.

[0046] Please combine Figure 1 As shown, the present invention provides an air intake duct experimental device with adjustable exhaust flow rate, comprising a driving device 1, a compression surface 2, an air intake duct side plate 3 symmetrically arranged on both sides of the compression surface, a lip cover 4 located above the air intake duct side wall, an exhaust cavity 5 located below the compression surface, a sliding plate 6 located below the exhaust cavity, brackets 7 located on both sides of the sliding plate, a bottom plate 8 located below the bracket, and supports 9 at four corners of the bottom plate.

[0047] The compression surface 2, the air inlet side panel 3, and the lip cover 4 together constitute the inner channel of the air inlet; the front end of the compression surface 2 is an isosceles pentagon, and its longer bottom side is the leading edge of the compression surface 2, and the shorter bottom side is connected to the inner channel of the air inlet. This section is straight, and gradually bends after entering the inner channel, and returns to straightness after the throat; the front end of the compression surface 2 is provided with a serrated transition zone 21 with the same width as the leading edge near the leading edge, so that the boundary layer transitions and thickens, except for the serrated transition zone. In addition, there is no obvious protrusion on the compression surface 2; the compression surface 2 is provided with a plurality of degassing grooves 22 from the entrance of the inlet channel to the throat, with 6 grooves in each group, and a total of 5 groups of 30 grooves; optical glass 31 is provided in the inlet side panels 3 on both sides to facilitate observation of the flow in the inner channel; the lip cover 4 covers the inlet side panels 3 to form a front-to-back through-channel; the degassing cavity 5 is located below the compression surface 2, divided into 5 mutually isolated degassing cavities and corresponding to the 5 groups of degassing grooves respectively, and the outlets of the degassing cavities are located in the same horizontal plane; the driving device 1 is placed above the cross beam on the front side of the bracket 7, connected to the sliding plate 6 and driven to translate relative to the degassing cavity 5 forward and backward to control the degassing flow of the inlet channel; the two sides of the sliding plate 6 are fixed with connecting blocks 61 by bolts and then respectively fixed on four sliders 72 to provide support for the sliding plate 6; the sliders 72 are distributed on two slide rails 71 in pairs, and the slide rails 71 are fixed on both sides of the bracket 7; the bracket 7 is connected and fixed to the supports 9 at the four corners of the bottom plate 8.

[0048] Please combine Figures 2 to 4 As shown in the figure, according to the original hypersonic large internal contraction ratio fixed geometric inlet configuration, the last stage compression surface is intercepted to the isolation section, and it is rotated by an angle of δ1 to make the compression surface horizontal, where δ1 is the deflection angle of the last stage compression surface of the original large internal contraction ratio inlet. The inlet entrance height H is obtained. in and throat height H throat , then the calculated inlet contraction ratio ICR should be greater than 2.5. Based on the simplified inlet configuration obtained, the front end of the compression surface is designed as an isosceles pentagon, with the longer bottom side being the leading edge of the model. The length of the leading edge is L fore Greater than the inlet width L in , and the other shorter bottom edge is connected to the inlet of the air inlet. At the same time, a zigzag transition belt is arranged at the front end of the compression surface, and its length is equivalent to the leading edge of the model. The rear end of the transition belt is at a distance L from the inlet of the air inlet. d Greater than or equal to 100mm. The transition belt has serrations protruding from the compression surface, and the serrations are designed as isosceles right triangles, i.e., θ = 90° and L zig =L zagOn this basis, the airflow deflection angle δ3 is obtained by adding the compression surface deflection angle δ1 and the lip mask deflection angle δ2, and then the shock wave angle β of the oblique shock wave is obtained by combining the calculation formula, thereby obtaining the oblique shock wave incident position. Several venting grooves are arranged in the area between the inlet and the throat before and after the oblique shock wave incident position, and 3 to 6 venting grooves are divided into a group, and the width L of the venting groove in each group is gap The distance between the slot and the bleed equal, the interval between groups is L ’ gap Need to be larger than the width of the venting groove L bleed . The deflation cavity is formed by a vertical depression from the lower bottom surface of the deflation groove. Each deflation cavity corresponds to a group of deflation grooves, which are separated from each other in the middle, and the bottom surface of the deflation cavity outlet is kept on the same horizontal plane. The sliding plate is rectangular and is placed horizontally close to the lower bottom surface of the deflation cavity outlet. A number of openings are provided in the middle of the sliding plate, which correspond to the deflation cavity outlets one by one, and have the same size and shape. The sliding plate is driven by a driving device and moves back and forth along the slide rails on both sides with the help of a slider. The driving device is placed in the middle of the front crossbeam of the support plate. In addition, the bottom plate and support structure are designed according to the actual space and installation requirements of the wind tunnel.

[0049] At the same time, a design method with specific parameters is provided to obtain the simplified experimental device structure of the above-mentioned air intake duct, and an embodiment of verification is provided, which is specifically described as follows:

[0050] The goal is to design a simplified experimental model of a hypersonic large internal contraction ratio inlet with an original design Mach number of 6.0. The simplified model has an incoming flow Mach number of about 3.8. The detailed implementation steps of the simplified experimental device of a large internal contraction ratio inlet with adjustable bleed flow and its design method are described.

[0051] Step 1: Combine Figure 2 As shown, according to the design flight state of the hypersonic aircraft and the corresponding aerodynamic performance index requirements of the inlet, the original hypersonic large internal contraction ratio fixed geometry inlet is designed, the design Mach number is 6.0, the flight angle of attack is 4°, and a three-stage compression layout is adopted. The deflection angle of the last stage compression surface is δ1=13.5°. In order to reduce the flight resistance, a horizontal lip cover is adopted, that is, the lip cover deflection angle δ2=0°;

[0052] Step 2: Combine Figure 3 As shown in FIG. 1 , the last stage compression surface to the isolation section is cut off, and the whole is rotated 13.5° clockwise to the level of the front end of the compression surface, thereby obtaining a simplified inlet configuration; in this process, the inlet profile does not change. In this embodiment, the inlet inlet height H in =30mm, intake throat height H throat =10mm, then its internal shrinkage ratio ICR is 3.0, which is greater than the required 2.5;

[0053] Step 3: Combine Figure 4 As shown, the front end of the compression surface is an isosceles pentagon. In this embodiment, the longer bottom side, i.e., the length L of the front edge of the model, is fore =140mm, air inlet width L in =80mm;

[0054] Step 4: The zigzag transition belt is arranged at the front end of the compression surface. Its length is also 140 mm. The distance between the rear end of the transition belt and the inlet entrance is L d =100mm;

[0055] Step 5: The serrated protrusion plane of the transition belt is an isosceles triangle with a vertex angle of θ = 90° and a length of L between the two sides. zig =L zag =5.65mm;

[0056] Step 6: Combine Figure 3 and Figure 4 As shown, the airflow deflection angle δ3 = 13.5°, which is the sum of the compression surface deflection angle δ1 = 13.5° and the lip mask deflection angle δ2 = 0°. According to the shock wave angle relationship of the oblique shock wave

[0057]

[0058] Wherein M1 is the incoming flow Mach number. In this embodiment, the incoming flow Mach number M1=3.8, and the shock wave angle β of the oblique shock wave of the lip shield is 26.325°. It is further obtained that the oblique shock wave incident point is about 208mm away from the leading edge of the model, and the air release grooves are arranged on both sides of this position;

[0059] Step 7: In this embodiment, 6 air release grooves are grouped into 5 groups, and the width of the air release grooves and the interval between the grooves L are gap =L bleed =2mm, interval between groups L ’ gap =2L bleed =4mm, the length of the venting groove is 76mm;

[0060] Step 8: According to the grouping of the air release grooves, there are 5 air release cavities pointing vertically downwards. The outlets of the 5 air release cavities are all on the same horizontal plane, and the area of ​​each outlet is A. bleed-out =12×76mm=912mm 2 =A bleed-in ;

[0061] Step 9, the sliding plate is rectangular, and 5 openings are set in the middle with the same shape and size as the outlet of the deflation cavity. It is placed horizontally close to the lower bottom surface of the outlet of the deflation cavity, and the openings correspond to the outlet of the deflation cavity one by one;

[0062] Step 10: The driving device is placed in the center of the front part of the bracket to drive the sliding plate to move forward and backward along the slide rails on both sides with the help of the slider;

[0063] Step 11. According to the actual space of the wind tunnel, four support columns are set at the four corners of this embodiment, which are fixed to the rectangular bottom plate by bolts, and the bottom plate is then fixed to the wind tunnel.

[0064] Through the above steps 1 to 11, a simplified experimental device of an inlet duct with a large internal contraction ratio and adjustable exhaust flow rate can be obtained.

[0065] In view of the present invention, a numerical simulation method is used to verify the performance of a simplified experimental device of an inlet duct with a large internal contraction ratio and adjustable bleed air flow rate when the incoming flow Mach number M0 is 3.8. Figure 5 The figure shows the inlet Mach number distribution of the embodiment of the present invention. As can be seen from the figure, the boundary layer generated by the simplified experimental device is turbulent and the thickness δ is about 3.6 mm, the mainstream flow is uniform, and the Mach number distribution is almost a straight line, indicating that the inlet flow quality of the device of the present invention is good. Figure 6 The figure shows the Mach number distribution cloud diagram of the embodiment of the present invention. It can be seen that the shock wave system in the inner channel is complete and clear, and the mainstream and bleed flow structures are obvious. When the bleed outlet is fully opened, the bleed flow rate is the largest, and there is no obvious separation at the lip mask shock wave incident point (region A); when the bleed outlet is reduced, the bleed flow rate is greatly reduced, and obvious large-scale separation occurs at the lip mask shock wave incident point (region B), and the flow structure in the inner channel becomes very complex. This shows that the device of the present invention can effectively control the bleed flow rate of the inlet duct, and at the same time, the inlet performance can be improved by adjusting the bleed flow rate.

[0066] In addition, there are many specific implementation methods and approaches of the present invention, and the above is only a preferred implementation of the present invention. It should be pointed out that for ordinary technicians in this technical field, if it does not depart from the principle of the present invention, it is also possible to make such improvements and modifications, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An air intake test device with adjustable exhaust flow, characterized in that: Including air intake system and regulation system; The air inlet system includes a compression surface, a lip cover located above the compression surface, and side panels located on both sides of the compression surface, and the lip cover, the compression surface and the side panels enclose an inner channel of the air inlet, a plurality of mutually independent deflation cavities are arranged below the compression surface, and the plurality of deflation cavities are arranged in sequence from front to back, a deflation groove is provided on the compression surface to connect the deflation cavity with the inner channel of the air inlet, and a deflation cavity outlet is provided at the bottom of each deflation cavity; The adjustment system includes a sliding plate, a driving device connected to the sliding plate, a slider connected to the sliding plate, and a sliding rail for the slider to move forward and backward; the sliding plate is arranged close to the outlet of the deflation chamber, and has a plurality of openings and baffles between two adjacent openings. The driving device drives the sliding plate to move forward and backward, so that the opening and / or the baffle of the sliding plate are located below the outlet of the deflation chamber, thereby changing the discharge area of ​​the outlet of the deflation chamber.

2. The air intake test device according to claim 1, characterized in that: The front section of the compression surface is an isosceles pentagon, the longer base of the isosceles pentagon is the front edge of the compression surface, and the shorter base is connected to the inner channel of the air inlet duct. The front section of the compression surface is straight, and the compression surface gradually bends after entering the inner channel and returns to being straight after the throat.

3. The air intake test device according to claim 2, characterized in that: A serrated transition zone having the same width as the front edge of the compression surface is arranged near the front edge of the compression surface.

4. The air intake test device according to claim 3, characterized in that: The slide rails have two mutually parallel ones extending from front to back, and the sliders are distributed on the two slide rails, and the sliders are located at the bottom of both sides of the slide plate.

5. The air intake test device according to claim 4, characterized in that: The air release groove is located on the compression surface from the entrance to the throat of the air inlet.

6. The air intake test device according to claim 5, characterized in that: A plurality of the degassing grooves are divided into a group, the width of the degassing grooves in each group is equal to the interval between the grooves, the interval between the groups is greater than the width of one degassing groove, and one group of degassing grooves is correspondingly connected to one degassing cavity.

7. The air intake test device according to claim 6, characterized in that: The outlet area of ​​the degassing cavity is equal to the sum of the areas of all degassing grooves of a corresponding group.

8. The air intake test device according to claim 7, characterized in that: The side plates are connected to the two sides of the compression plate, and optical glass is arranged in the side plates.

9. The air intake test device according to claim 8, characterized in that: The driving device is connected with the sliding plate, and drives the sliding plate to move forward and backward along the sliding rails on both sides with the help of the sliding blocks.

10. A method for designing an air intake test device with adjustable exhaust flow rate as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1, determine the aerodynamic performance index requirements of the air inlet, design the configuration of the air inlet accordingly, and obtain the deflection angle δ1 of the air inlet compression surface and the deflection angle δ2 of the lip mask; Step 2: Based on the inlet duct configuration obtained in step 1, the last stage compression surface to the isolation section is intercepted, and the compression surface deflection angle δ1 is rotated to make the front end of the compression surface horizontal, and a simplified inlet duct configuration is obtained, and its internal contraction ratio is ICR=H in / H throat Where ICR is the internal contraction ratio, H in is the inlet entrance height, H throat is the inlet throat height, and the internal contraction ratio of the simplified inlet configuration is greater than 2.5; Step 3: Based on the simplified air inlet configuration obtained in step 2, the front end of the compression surface is an isosceles pentagon, the longer bottom side is the leading edge of the model, and the length of the longer bottom side is greater than the width of the air inlet entrance; Step 4: Arrange a zigzag transition zone at the front end of the compression surface. The length of the transition zone is equivalent to the front edge of the model. The rear end of the transition zone is L away from the inlet entrance. d ≥100mm; Step 5, the sawtooth of the transition belt protrudes from the plane, and the sawtooth shape is an isosceles right triangle; Step 6: Based on the simplified inlet duct configuration obtained in step 5, the airflow deflection angle δ3 is calculated according to the compression surface deflection angle δ1 and the lip mask deflection angle δ2, and the following is obtained: δ3=δ1+δ2 According to the calculation formula of the shock angle β of the oblique shock wave The incident position of the oblique shock wave is obtained, where M1 is the incoming flow Mach number, and multiple air release slots are arranged in front and behind the incident position as the center; Step 7: To avoid air cross-talk, several air release grooves on the compression surface are divided into a group, the width of the air release grooves in each group is equal to the interval between the grooves, and the interval between the groups is greater than the width of one air release groove; Step 8, the deflation cavities are vertically recessed from the bottom surface of the deflation grooves according to the groups, each deflation cavity corresponds to a group of deflation grooves, the outlet area of ​​the deflation cavity is equal to the sum of the areas of all the deflation grooves in the corresponding group, and the outlets of the deflation cavities are all in the same plane; Step 9, the sliding plate is placed close to the deflation cavity, and a plurality of openings and baffles are provided on the sliding plate. The sliding plate moves forward and backward so that the openings and / or baffles are located below the outlet of the deflation cavity, thereby changing the discharge area of ​​the outlet of the deflation cavity; Step 10: The driving device is placed in the center of the front part of the bracket, and drives the sliding plate to move forward and backward along the slide rails on both sides with the help of the slider; Step 11: Design the side panels, bottom panel and bracket according to the actual space and installation requirements of the wind tunnel.

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