A shock controller and method of designing the same

Abstract

The application discloses a shock wave controller and a design method thereof, which comprises an isolation section, two control pieces and four wedge blocks. The upper and lower surfaces of the control piece are smooth planes, the front end is a windward end, the rear end is a leeward end, the windward end and the leeward end are provided with chamfers, the other two ends are fixed ends, at least two holes are arranged on each fixed end, the wedge block is composed of two ladder blocks, the two ladder blocks are symmetrically connected through a countersunk screw, the wedge block is fixed in a groove arranged in the isolation section through the screw, and each two wedge blocks are fixedly connected with a control piece. The shock wave controller can change the flow field structure, increase the anti-back pressure capacity of the isolation section, control the shock wave string in the control section during the process that the back pressure increases and the shock wave string does not move upwards, and improve the flow field symmetry and the total pressure recovery coefficient.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of supersonic and hypersonic aircraft inlet, and particularly relates to a shock controller and a design method thereof. BACKGROUND

[0002] Shock wave and its interference phenomenon widely exist in the internal and external flow field of supersonic and hypersonic aircraft, among which the shock wave and boundary layer interference has been attracting scholars for more than half a century, and is still a hot research direction. The achievements in this field provide important theoretical and technical support for the innovative development of aerospace vehicles.

[0003] High-speed aircraft inevitably induces shock wave structure in the process of flying above the speed of sound, and the interference of shock wave and components will cause more complex flow field, bringing severe challenges to the aerodynamics of high-speed aircraft. The shock wave and boundary layer interference phenomenon refers to the process that the adverse pressure gradient caused by the shock wave causes the boundary layer to thicken or even separate and reattach, which has a significant impact on the overall performance of the aircraft and the propulsion system. For the inlet, the shock wave and boundary layer interference will directly change the air flow pattern entering the engine, reducing the engine efficiency. Especially when the shock wave is very strong and separation occurs, the entire flow field structure will change greatly. The thickening or separation of the boundary layer will reduce the effective profile of the inlet, and in severe cases, it may even cause the inlet to not start. In the air-breathing engine, the supersonic condition in the isolation section depends on a series of shock wave compression to subsonic condition. This series of shock wave structure is called shock wave train, which is a special internal flow phenomenon. The characteristic of the shock wave train flow field is the strong shock wave and boundary layer interference, which will lead to flow separation and flow instability, reducing the performance of the engine.

[0004] Therefore, it is necessary to design a shock controller to control the shock wave train in the isolation section of the inlet. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a shock controller and a design method thereof, to solve the problems of asymmetric shock wave train and low total pressure recovery coefficient in the isolation section of the inlet in the prior art. The wedge and control piece are matched together in the present application, the shock wave train is controlled at a certain position by the shock controller, the anti-back pressure capability of the isolation section is improved and the total pressure loss is reduced, and the present application has the advantages of simple design and low processing difficulty.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] The shock controller of the present application comprises: an isolation section, two control pieces and four wedge blocks; wherein,

[0008] The control piece has smooth upper and lower surfaces, a windward end, a leeward end, and chamfers on the windward end and the leeward end, and the other two ends are fixed ends, and at least two holes are arranged on each fixed end.

[0009] The wedge block is composed of two stepped blocks, and the two stepped blocks are symmetrically connected by a countersunk screw.

[0010] Further, the control piece is a stainless steel rectangular sheet, the width of which is 10 mm longer than the width of the isolation section, and the thickness is 0.5 mm, and the windward end and the leeward end have chamfers, so that the windward end and the leeward end become sharp.

[0011] Further, the two stepped blocks in the wedge block each have a slope, and when the two slopes are fitted, the two stepped blocks are combined into a cuboid.

[0012] Further, the fixed end of the control piece is fitted with the slope of the stepped block, and the countersunk screw connecting the stepped blocks passes through the hole of the fixed end of the control piece to fixedly connect the wedge block and the control piece.

[0013] Further, the one control piece and the two wedge blocks constitute a control unit, and two control units constitute a shock wave controller.

[0014] The design method of the shock wave controller of the application is based on the above-mentioned shock wave controller, and comprises the following steps:

[0015] Step 1: determining the attack angle required by the control piece according to the back pressure ratio of the flow field;

[0016] Step 2: determining the length of the control piece according to the length, width and height of the isolation section;

[0017] Step 3: determining the distance between the windward ends of the two control pieces according to the back pressure ratio of the flow field and the height of the isolation section;

[0018] Step 4: determining the horizontal position of the control piece in the isolation section according to the back pressure ratio of the flow field, the length of the isolation section and the length of the control piece;

[0019] Step 5: determining the length and height of the two stepped blocks in the same wedge block according to the attack angle and length of the control piece in the flow field, so as to fix the control piece.

[0020] The application has the following beneficial effects:

[0021] The shock wave controller of the application can change the flow field structure, increase the anti-back pressure capacity of the isolation section, control the shock wave train in the control section during the process of increasing the back pressure and the shock wave train moving upstream, and improve the flow field symmetry and total pressure recovery coefficient. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the shock wave controller of the application.

[0023] Figure 2 It is a sectional schematic diagram of the shock wave controller of the application.

[0024] Figure 3 It is an effect diagram of the shock wave controller of the application on the total pressure recovery coefficient. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of those skilled in the art, the application is further described below in combination with the embodiments and the drawings, and the content mentioned in the embodiments is not a limitation on the application.

[0026] Referring to Figure 1 , Figure 2 The shock wave controller of the application comprises an isolation section 1, two control pieces 2 and four wedge blocks 3, wherein,

[0027] The upper and lower surfaces of the control piece 2 are smooth planes, the front end is a windward end, the rear end is a leeward end, and the windward end and the leeward end are provided with chamfers, and the other two ends are fixed ends, and at least two holes are provided on each fixed end;

[0028] The wedge block 3 is composed of two ladder blocks 31, and the two ladder blocks are symmetrically connected through a countersunk screw; the wedge block 3 is fixed in the groove provided in the isolation section through a screw; and each two wedge blocks 3 are fixedly connected with one control piece 2.

[0029] The control piece 2 is a stainless steel rectangular sheet, the width of which is 10 mm longer than the width of the isolation section, and the thickness is 0.5 mm, and the windward end and the leeward end are provided with chamfers, so that the windward end and the leeward end become sharp.

[0030] Each of the two ladder blocks in the wedge block 3 has an inclined surface, and when the two inclined surfaces are fitted, the two ladder blocks are spliced into a cuboid, the ladder block far away from the wall surface of the isolation section is called a far wall ladder block, and the ladder block close to the wall surface of the isolation section is called a near wall ladder block.

[0031] The fixed end of the control piece 2 is fitted with the inclined surface of the ladder block, and the countersunk screw connecting the ladder blocks passes through the hole of the fixed end of the control piece 2 to fixedly connect the wedge block 3 and the control piece 2.

[0032] One control piece 2 and two wedge blocks 3 constitute a control unit, and two groups of control units constitute the shock wave controller.

[0033] The present invention provides a design method for a shock wave controller, based on the above-mentioned shock wave controller, comprising the following steps:

[0034] Step 1: Determine the required angle of attack α for the control plate based on the back pressure ratio γ of the flow field:

[0035]

[0036] When the back pressure ratio γ of the flow field is less than the back pressure ratio a when the shock train appears or greater than the back pressure ratio b when the flow field does not start, the control plate angle of attack α is 0°; when the back pressure ratio γ of the flow field is between a and b, the control plate angle of attack α is k1*θ°, and the angle of attack is generally a small angle, k1 is the proportional coefficient, θ° is the reference angle, and the default value is 1°.

[0037] Step 2: Determine the length l of the control piece based on the isolation section length L, width D, and height H:

[0038] l=k2L+k3D+k4H

[0039] In the formula, k2, k3, and k4 are all proportionality coefficients;

[0040] Step 3: Determine the distance d between the windward ends of the two control plates based on the back pressure ratio γ of the flow field and the height H of the isolation section. k :

[0041]

[0042] When the back pressure ratio γ of the flow field is less than the back pressure ratio a when the shock wave occurs or greater than the back pressure ratio b when the flow field does not start, the distance d between the leading edges of the two control plates is... k The control plate does not control the height H of the isolation section; when the back pressure ratio γ of the flow field is between a and b, the control plate spacing is k5*H, where k5 is the proportionality coefficient.

[0043] Step 4: Determine the horizontal distance L1 between the control plate and the foremost edge of the isolation section based on the back pressure ratio γ of the flow field, the length L of the isolation section, and the length l of the control plate.

[0044] L1 = k6*(Ll)*(1-γ)

[0045] In the formula, k6 is the proportionality coefficient;

[0046] Step 5: Determine the length and width of the two trapezoidal blocks in the same wedge based on the required angle of attack and length of the control plate in the flow field, thereby fixing the control plate; for the known length l of the control plate, height h of the wedge, and thickness d of the control plate, the relationship between the angle of attack α of the control plate and the height of the right-angled side of the trapezoidal block constituting the wedge is as follows:

[0047]

[0048] In the formula, h1 is the long side of the far wall step block, h2 is the short side of the near wall step block, h3 is the long side of the near wall step block, and h4 is the short side of the far wall step block.

[0049] In an example, the application is applied to a certain supersonic test, and the specific steps are as follows:

[0050] 1) The total pressure of the incoming flow is 400000 Pa, and the back pressure ratio γ is 0.25 to 0.35;

[0051] 2) According to the formula:

[0052] L1=k6*(L-l)*(1-γ)

[0053] d k =k5*H

[0054] The horizontal position of the control piece is determined to be 265mm away from the front end of the isolation section, and the spacing between the windward ends of the two control pieces is 28mm;

[0055] 3) According to the formula:

[0056] α=k1*θ°

[0057] The selected attack angle of the control piece is 2°, the thickness of the control piece is 0.5mm, the length l of the control piece is 90mm, the height h of the wedge is 10mm, and the heights of the different sides of the step block are determined as:

[0058]

[0059]

[0060] Figure 3 It is illustrated that within a certain back pressure ratio range, the total pressure recovery coefficient is improved after the shock controller is added in the isolation section compared with no control; and the feasibility of the application for improving the total pressure recovery coefficient after controlling the shock string in the isolation section is verified.

[0061] The application has many specific application approaches, and the above description is only a preferred embodiment of the application, and it should be pointed out that for ordinary skilled persons in the technical field, some improvements can be made without departing from the principle of the application, and these improvements should also be regarded as the protection range of the application.

Claims

1. A design method for a shock wave controller, the shock wave controller comprising: The isolation section (1), two control plates (2), and four wedges (3) are included; among them, The control plate (2) has smooth planes on the upper and lower sides, the front end is the windward end, the rear end is the leeward end, and the windward end and the leeward section are chamfered. The other two sides are fixed ends, and each fixed end is provided with at least two holes. The wedge (3) is composed of two stepped blocks (31), which are symmetrically connected by countersunk screws; the wedge (3) is fixed in the groove provided in the isolation section by screws; a control piece (2) is fixedly connected to every two wedges (3); The method is characterized by the following steps: Step 1: Determine the required angle of attack for the control plate based on the back pressure ratio of the flow field; Step 2: Determine the length of the control plate based on the length, width, and height of the isolation section; Step 3: Determine the spacing between the windward ends of the two control plates based on the back pressure ratio of the flow field and the height of the isolation section; Step 4: Determine the horizontal position of the control plate in the isolation section based on the back pressure ratio of the flow field, the length of the isolation section, and the length of the control plate; Step 5: Determine the length and height of the two stepped blocks in the same wedge based on the angle of attack and length of the control plate in the flow field, so as to fix the control plate.

2. The design method of the shock wave controller according to claim 1, characterized in that, The control plate (2) is a rectangular thin sheet of stainless steel, which is 10 mm wider than the isolation section and 0.5 mm thick. The windward and leeward ends are chamfered to make them sharp.

3. The design method of the shock wave controller according to claim 1, characterized in that, The two stepped blocks in the wedge (3) each have an inclined surface. When the two inclined surfaces are in contact, the two stepped blocks are assembled into a cuboid. The stepped block that is far from the wall of the isolation section is called the far wall stepped block, and the stepped block that is close to the wall of the isolation section is called the near wall stepped block.

4. The design method of the shock wave controller according to claim 1, characterized in that, The fixed end of the control plate (2) is attached to the inclined surface of the ladder block, and the countersunk screw connecting the ladder block passes through the hole of the fixed end of the control plate (2) to fix the wedge block (3) and the control plate (2) together.

5. The design method of the shock wave controller according to claim 1, characterized in that, The control piece (2) and the two wedges (3) constitute a control unit; the two control units constitute a shock wave controller.

6. The design method of the shock wave controller according to claim 1, characterized in that, Step 1 specifically includes: determining the angle of attack α required for the control plate based on the back pressure ratio γ of the flow field. When the back pressure ratio γ of the flow field is less than the back pressure ratio a when the shock train appears or greater than the back pressure ratio b when the flow field does not start, the control plate angle of attack α is 0°; when the back pressure ratio γ of the flow field is between a and b, the control plate angle of attack α is k1*θ°, and the angle of attack is generally a small angle, k1 is the proportional coefficient, θ° is the reference angle, and the default value is 1°.

7. The design method of the shock wave controller according to claim 6, characterized in that, Step 2 specifically includes: determining the length l of the control piece based on the isolation section length L, width D, and height H. l=k2L+k3D+k4H In the formula, k2, k3, and k4 are all proportionality coefficients.

8. The design method of the shock wave controller according to claim 7, characterized in that, Step 3 specifically includes: determining the distance d between the windward ends of the two control plates based on the back pressure ratio γ of the flow field and the height H of the isolation section. k : When the back pressure ratio γ of the flow field is less than the back pressure ratio a when the shock wave occurs or greater than the back pressure ratio b when the flow field does not start, the distance d between the leading edges of the two control plates is... k The control plate does not control the height H of the isolation section; when the back pressure ratio γ of the flow field is between a and b, the control plate spacing is k5*H, where k5 is the proportionality coefficient.

9. The design method of the shock wave controller according to claim 8, characterized in that, Step 4 specifically includes: determining the horizontal distance L1 between the control plate and the foremost edge of the isolation section based on the back pressure ratio γ of the flow field, the length L of the isolation section, and the length l of the control plate. L1 = k6*(Ll)*(1-γ) In the formula, k6 is the proportionality coefficient; Step 5 specifically includes: determining the length and width of the two stepped blocks in the same wedge based on the required angle of attack and length of the control plate in the flow field, thereby fixing the control plate; for the known length l of the control plate, height h of the wedge, and thickness d of the control plate, the relationship between the angle of attack α of the control plate and the height of the right-angled side of the stepped block constituting the wedge is as follows: In the formula, h1 is the long side of the far wall trapezoidal block, h2 is the short side of the near wall trapezoidal block, h3 is the long side of the near wall trapezoidal block, and h4 is the short side of the far wall trapezoidal block.

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