Variable mach number wind tunnel experimental device based on rigid-flexible coupling deformation structure

Abstract

The application relates to a variable-Mach-number wind tunnel experimental device based on a rigid-flexible coupling deformation structure, which comprises a wind tunnel sequentially connected by a contraction section, an air inlet section, a nozzle section and an experimental section. The internal flow passage of the nozzle section is sequentially connected by a flexible inlet transition section, a rigid contraction section and a flexible expansion section arranged symmetrically in the up-down direction. A servo motor drives the rigid contraction section to translate along the direction defined by the sliding groove through a gear and rack transmission to adjust the height of the throat, while the other end of the rigid contraction section drives the flexible expansion section to produce adaptive deformation and move horizontally along the inner plate surface of the second flat plate. According to the above technical scheme, the experimental device drives the rigid contraction section of the nozzle section to translate through the servo motor to change the height of the throat, drives the upstream flexible inlet transition section to deform, drives the downstream flexible expansion section to produce adaptive deformation and move horizontally along the sliding groove cavity, and realizes the dynamic change of the Mach number.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aerodynamic experimental devices, in particular to a variable Mach number wind tunnel experimental device based on a rigid-flexible coupling deformation structure. BACKGROUND

[0002] With the rapid development of aerospace technology, the performance requirements of aircraft are becoming higher and higher. Especially under the condition of wide range of variable Mach number flight, the aircraft will encounter complex aerodynamic and thermodynamic problems, such as shock wave, boundary layer separation, thermal protection, etc. In order to study the aerodynamic characteristics of the aircraft under these wide speed range conditions on the ground, it is urgent to develop a wind tunnel experimental device that can realize variable Mach number. For the converging-diverging nozzle that generates supersonic flow, the expansion ratio of the nozzle (i.e. the ratio of the outlet area to the throat area) determines the Mach number at the nozzle outlet. Therefore, for the variable Mach number wind tunnel, the change of the nozzle expansion ratio and the profile is the key technology. At present, the research on the nozzle section of the variable Mach number wind tunnel scheme mainly includes flexible wall nozzle and symmetrical opening and closing nozzle. The variable Mach number wind tunnel scheme of the flexible wall nozzle adopts a series of pistons moving up and down to drive the full flexible nozzle wall to deform controllably, so as to change the Mach number of the nozzle flow field. The symmetrical opening and closing nozzle usually adopts a symmetrical solid wall nozzle, and the nozzle profile is rotated around one end of the nozzle as the rotation axis, and the other end is moved up and down to change the contraction ratio of the nozzle, so as to change the Mach number of the nozzle flow field. In addition, some wind tunnels change the specific heat ratio of the test gas to indirectly change the Mach number of the flow field.

[0003] The existing variable Mach number wind tunnel experimental device mainly has the following shortcomings: (1) the full flexible wall nozzle mostly adopts a multi-point actuator, which is difficult to control and the implementation method is complex, and the Mach number change of the flow field in the nozzle is difficult to control continuously and accurately; (2) if the nozzle adopts a symmetrical opening and closing rigid rotating wall, the flow field will be distorted when the wall rotates, which will limit the Mach number change range of the single nozzle to less than 2, and it is difficult to cross high Mach number; (3) the specific heat ratio of the test gas can be changed to indirectly change the Mach number of the gas flow, but the adjustable change range of this method is narrow, and the storage, transportation and recovery of special gas are involved. In addition, the change of the experimental medium will also affect the accuracy and consistency of the results. SUMMARY

[0004] The purpose of the present application is to provide a variable Mach number wind tunnel experimental device based on a rigid-flexible coupling deformation structure, which changes the throat height by driving the rigid contraction section of the nozzle section to translate through a servo motor, and drives the upstream flexible inlet transition section to deform, the downstream flexible expansion section to adaptively deform and move horizontally along the slide cavity, to realize dynamic change of wide range of Mach number.

[0005] In order to achieve the above object, the present application adopts the following technical scheme: a wind tunnel comprising a contraction section, an inlet section, a nozzle section and an experimental section connected in sequence, the internal flow passages of the contraction section, the inlet section, the nozzle section and the experimental section are communicated in sequence to form a gas flow passage of the wind tunnel, the inlet end of the contraction section is directly connected with a gas source, the gas entering the gas flow passage from the gas source forms a target Mach number gas, the nozzle section is in the form of a whole rectangle, is enclosed by a left side plate, a right side plate symmetrically arranged in the left-right direction and an upper cover assembly, a lower cover assembly symmetrically arranged in the up-down direction, the upper cover assembly and the lower cover assembly each comprise a first flat plate arranged close to the inlet section and a second flat plate arranged close to the experimental section, the outer surfaces of the first flat plate and the second flat plate are located in the same horizontal plane and a gap is left between the two, the gap is connected with a gear box in a sealed manner;

[0006] The internal flow passage of the nozzle section is a contraction-expansion type flow passage, is connected in sequence by a flexible inlet transition section, a rigid contraction section and a flexible expansion section symmetrically arranged in the up-down direction, the flexible inlet transition section is a flexible plate, one end of the flexible plate is in plug-in cooperation with the end of the first flat plate, the other end of the flexible plate is always lapped on the inner surface of the rigid contraction section, the rigid contraction section is a rigid plate, one end of the rigid plate is located in the gear box and is matched with a sliding groove arranged in the gear box, the other end of the rigid plate is located in the internal part of the nozzle section and is connected with the flexible expansion section, the sliding groove is arranged in a vertical direction in an inclined manner, the flexible expansion section is a flexible plate, one end of the flexible plate is in plug-in cooperation with the rigid contraction section, the other end of the flexible plate is in close contact with the inner plate surface of the second flat plate;

[0007] A gear rack is arranged on the outer surface of one end of the rigid contraction section located in the gear box, a gear engaged with the gear rack is fixed in the gear box, the gear is driven by a servo motor, the servo motor drives the rigid contraction section to move along the direction defined by the sliding groove through gear and gear rack transmission to adjust the height of the throat, at the same time, the other end of the rigid contraction section drives the flexible expansion section to produce self-adapting deformation and moves horizontally along the inner plate surface of the second flat plate;

[0008] A laser displacement sensor is further connected in a sealed manner on the top of the gear box, the laser displacement sensor is connected with a signal processor, the emitting end of the laser displacement sensor is located in the gear box, and the inclination of the ranging light path emitted by the emitting end is always consistent with the inclination of the sliding groove.

[0009] The side of the gear box is further provided with a sealed cavity fixed on the first flat plate, the left side plate and the right side plate, the lower part of the sealed cavity is open, a closed space is formed between the sealed cavity and the first flat plate and the lapped part of the rigid contraction section and the flexible inlet transition section, the end face of the gear box close to the sealed cavity is in an open state, the open end is provided with a sliding groove matched with the rigid contraction section, and the open end and the end face close to the sealed cavity are integrated and sealed.

[0010] The laser displacement sensor is placed in the sensor mounting sleeve and positioned by the L-shaped support arranged at the bottom of the sensor mounting sleeve, the sensor mounting sleeve comprises a sleeve body sealingly connected with the top of the gear box and an upper cover sealingly connected with the top of the sleeve body, the bottom of the sleeve body is open to allow the emission end and the receiving end of the laser sensor not to be blocked, the L-shaped support is fixed at one end of the bottom of the sleeve body, the data transmission line of the laser displacement sensor is connected with the signal processor after passing through the upper cover, and the data transmission line and the upper cover are sealingly connected.

[0011] The flexible expansion section comprises a horizontal plate and an arc-shaped plate, the rear half of the horizontal plate is attached to the rear half of the arc-shaped plate and connected as a whole, and an elastic opening is formed between the front half of the horizontal plate and the front half of the arc-shaped plate; the front half of the horizontal plate is located in the slide cavity arranged on the second flat plate, and the front half of the arc-shaped plate is insertedly connected with the rigid contraction section.

[0012] The vertical plate surface of the L-shaped slide plate is fixed to the end surface of the second flat plate close to the first flat plate, the horizontal plate surface of the slide plate is parallel to the second flat plate and has a spacing with the second flat plate, the spacing forms the slide cavity for accommodating the front half of the horizontal plate, and the left side plate and the right side plate are respectively provided with mounting grooves matched with the cross sections of the two side edges of the slide plate.

[0013] The transition plate is a rigid plate and is connected to the outer surfaces of the rigid contraction section and the arc-shaped plate, and the inner surfaces of the flexible inlet transition section, the rigid contraction section and the flexible expansion section always form smooth curved surface connections.

[0014] The output shaft of the servo motor is connected with the gear shaft of the gear through a shaft coupling, the two ends of the gear shaft are respectively connected with the left side plate and the right side plate of the nozzle section through bearings, the bearing cover is arranged at the connection position between the left side plate and the bearing to form a seal between the inner cavity of the gear box and the outside, and the bearing transparent cover is arranged at the connection position between the right side plate and the bearing to form a seal between the inner cavity of the gear box and the outside; the servo motor and the shaft coupling are located outside the nozzle section, and the servo motor is fixed on the motor mounting frame through the lifting frame.

[0015] The internal flow channel of the contraction section is a variable-diameter flow channel with a circular inlet cross section and a rectangular outlet cross section, the internal flow channel of the inlet section is a rectangular flow channel, the internal flow channel of the nozzle section is a contraction-expansion type flow channel, and the internal flow channel of the experimental section is a rectangular flow channel; the contraction section, the inlet section, the nozzle section and the experimental section are connected through flanges.

[0016] The beneficial effects of the present application are as follows:

[0017] 1) The present application drives the rigid contraction section to move by a servo motor, adjusts the throat height, changes the ratio of the exit area of the nozzle section to the throat area, drives the flexible inlet transition section upstream to deform, and at the same time, the flexible expansion section of the nozzle section generates smooth deformation and translation movement along the slide cavity direction, so that the inner surfaces of the flexible inlet transition section, the rigid contraction section and the flexible expansion section always form smooth curved surface connection, realizes the change of the Mach number of the test section and effectively reduces the flow field disturbance caused by the discontinuity of the wall surface profile during the change of the experimental device.

[0018] 2) Compared with the full-flexible wall nozzle structure using a multi-point actuator mechanism, the present application has low control difficulty and simple implementation.

[0019] 3) Compared with the traditional rigid rotating wall nozzle structure, the changed flow field is more uniform, and the Mach number in the test section can be continuously and accurately changed in real time during the experiment.

[0020] 4) Compared with the method of changing the Mach number in the test section by changing the specific heat ratio of the experimental gas, the Mach number range that can be adjusted is wider.

[0021] 5) The ranging light path of the laser displacement sensor is always parallel to the direction of movement of the rigid contraction section rack, which can ensure that the measured position of the ranging point on the rigid contraction section does not change. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic diagram of the three-dimensional structure of the present application Figure 1 ;

[0023] Figure 2 is a schematic diagram of the three-dimensional structure of the present application Figure 2 ;

[0024] Figure 3 is a schematic diagram of the three-dimensional structure of the present application nozzle section;

[0025] Figure 4 is a sectional view of the present application nozzle section;

[0026] Figure 5 is a schematic diagram of the internal structure of the present application nozzle section after removing the left side plate;

[0027] Figure 6 is an enlarged view of A of Figure 5 ;

[0028] Figure 7 is a schematic diagram of the connection of the servo motor and the gear of the present application;

[0029] Figure 8 is a schematic diagram of the structure of the motor mounting frame of the present application;

[0030] Figure 9 is the installation schematic diagram of the slide board of the present application;

[0031] Figure 10 is the exploded structural schematic diagram of the slide board, the second flat plate and the flexible expansion section of the present application;

[0032] Figure 11 is the connection structural schematic diagram of the rigid contraction section and the flexible expansion section of the present application;

[0033] Figure 12 is the installation schematic diagram of the laser displacement sensor of the present application;

[0034] Figure 13 is the exploded structural schematic diagram of Figure 12 ;

[0035] Figure 14 is the structural schematic diagram of the displacement sensor of the present application;

[0036] Figure 15 is the cooperation schematic diagram of the displacement sensor and the rigid contraction section of the present application;

[0037] Figure 16 is the structural schematic diagram of the sleeve body in the sensor installation sleeve of the present application Figure 1 ;

[0038] Figure 17 is the structural schematic diagram of the sleeve body in the sensor installation sleeve of the present application Figure 2 ;

[0039] Figure 18 is the structural schematic diagram of the gear box of the present application Figure 1 ;

[0040] Figure 19 is the structural schematic diagram of the gear box of the present application Figure 2 ;

[0041] Figure 20 is the structural schematic diagram of the sealed cavity of the present application;

[0042] Fig. 21(a) is the flow field Mach cloud picture of the nozzle section and the experimental section of the embodiment one of the present application;

[0043] Fig. 21(b) is the y-Ma picture of the embodiment one of the present application;

[0044] Fig. 21(c) is the corresponding nozzle section cross-sectional view of the embodiment one of the present application;

[0045] Fig. 22(a) is the flow field Mach cloud picture of the nozzle section and the experimental section of the embodiment two of the present application;

[0046] Fig. 22(b) is the y-Ma picture of the embodiment two of the present application;

[0047] Figure 22(c) is a cross-sectional view of the nozzle section corresponding to Embodiment 2 of the present invention;

[0048] Figure 23(a) is a Mach cloud diagram of the flow field of the nozzle section and the experimental section in Embodiment 3 of the present invention;

[0049] Figure 23(b) is the y-Ma plot of Embodiment 3 of the present invention;

[0050] Figure 23(c) is a cross-sectional view of the nozzle section corresponding to Embodiment 3 of the present invention;

[0051] Figure 24(a) is a Mach cloud diagram of the flow field of the nozzle section and the experimental section in Embodiment 4 of the present invention;

[0052] Figure 24(b) is a y-Ma plot of Embodiment 4 of the present invention;

[0053] Figure 24(c) is a cross-sectional view of the nozzle section corresponding to Embodiment 4 of the present invention.

[0054] The labels in the above figures are as follows: contraction section 1, air intake section 2, nozzle section 3, left side plate 301, right side plate 302, first flat plate 303, second flat plate 304, mounting groove 305, flexible inlet transition section 31, rigid contraction section 32, rack 321, flexible expansion section 33, horizontal plate 331, first sealing groove 3311, second sealing groove 3312, arc-shaped plate 332, third sealing groove 3321, slide cavity 34, slide plate 35, transition plate 36, experimental section 4, gearbox 5, slide groove 51, gear 52, servo motor 53. 531 Lifting frame, 54 Coupling, 55 Gear shaft, 56 Bearing, 57 Bearing cover, 58 Bearing cover, 59 Motor mounting bracket, 60 Laser displacement sensor, 61 Transmitter, 62 Receiver, 63 Ranging optical path, 631 Ranging point, 64 Sensor mounting sleeve, 641 Sleeve body, 642 Top cover, 65 L-shaped support leg, 66 Data transmission line, 7 Signal processor, 8 Sealing cavity, 81 Sealing groove, 9 Experimental support platform, 91 First flange, 92 Second flange, 93 Third flange, 94 Fourth flange, 95 Fifth flange, 96 Sixth flange. Detailed Implementation

[0055] The present invention will be further described below with reference to the accompanying drawings:

[0056] like Figure 1 , Figure 2 The wind tunnel experimental device based on a rigid-flexible coupling deformation structure is shown. It includes a wind tunnel consisting of a contraction section 1, an inlet section 2, a nozzle section 3 and an experimental section 4 connected in sequence. The internal flow channels of the contraction section 1, the inlet section 2, the nozzle section 3 and the experimental section 4 are connected in sequence to form the gas flow channel of the wind tunnel. The inlet end of the contraction section 1 is directly connected to the gas source. After the gas enters the gas flow channel from the gas source, it forms the target Mach number gas.

[0057] Further, the internal flow passage of the contraction section 1 is a variable-diameter flow passage with a circular inlet cross-section and a rectangular outlet cross-section, the internal flow passage of the inlet section 2 is a rectangular flow passage, the internal flow passage of the nozzle section 3 is a contraction-expansion type flow passage, and the internal flow passage of the experimental section 4 is a rectangular flow passage; the contraction section 1, the inlet section 2, the nozzle section 3, and the experimental section 4 are connected through flanges. Specifically, the first flange 91 in the contraction section 1 is connected to the second flange 92 in the inlet section 2, the third flange 93 in the inlet section 2 is connected to the fourth flange 94 in the nozzle section 3, and the fifth flange 95 in the nozzle section 3 is connected to the sixth flange 96 in the experimental section 4, wherein the fourth flange 94 and the fifth flange 95 at both ends of the nozzle section 3 are L-shaped flanges, and the entire experimental device is placed on the experimental support table 9.

[0058] Further, as shown in Figure 3 、 Figure 4 、 Figure 5 , the nozzle section 3 is in the shape of a rectangle as a whole, and is enclosed by the left side plate 301 and the right side plate 302 arranged symmetrically in the left-right direction, and the upper cover assembly and the lower cover assembly arranged symmetrically in the up-down direction. The upper cover assembly and the lower cover assembly each include the first flat plate 303 arranged close to the inlet section 2 and the second flat plate 304 arranged close to the experimental section 4. The outer surfaces of the first flat plate 303 and the second flat plate 304 are located in the same horizontal plane and have a gap therebetween, and the gap is connected to the gear box 5 in a sealed manner.

[0059] Further, the internal flow passage of the nozzle section 3 is a contraction-expansion type flow passage, which is sequentially connected by the flexible inlet transition section 31, the rigid contraction section 32, and the flexible expansion section 33 arranged symmetrically in the up-down direction. Specifically, the flexible inlet transition section 31 is a flexible plate, one end of which is inserted and fitted with the end of the first flat plate 303, and the other end of which is always lapped on the inner surface of the rigid contraction section 32; the rigid contraction section 32 is a rigid plate, one end of which is located in the gear box 5 and is matched with the sliding groove 51 arranged in the gear box 5, and the other end of which is located inside the nozzle section 3 and is connected with the flexible expansion section 33, and the sliding groove 51 is arranged in a vertical direction; the flexible expansion section 33 is a flexible plate, one end of which is inserted and fitted with the rigid contraction section 32, and the other end of which is attached to the inner plate surface of the second flat plate 304.

[0060] Further, as shown in Figure 6 、 Figure 9 、 Figure 10As shown, the flexible expansion section 33 comprises a horizontal plate 331 and an arc plate 332, the rear half of the horizontal plate 331 is attached to the rear half of the arc plate 332 and connected as a whole, and an elastic opening is formed between the front half of the horizontal plate 331 and the front half of the arc plate 332; the front half of the horizontal plate 331 is located in the slide cavity 34 provided on the second flat plate 304, and the front half of the arc plate 332 is inserted and matched with the rigid contraction section 32. Specifically, the inner plate surface of the second flat plate 304 is fixed with an L-shaped slide plate 35, the vertical plate surface of the slide plate 35 is fixed with the end surface of the second flat plate 304 close to the first flat plate 303, and the horizontal plate surface of the slide plate 35 is parallel to the second flat plate 304 and has a spacing with the second flat plate 304, which forms the slide cavity 34 for accommodating the front half of the horizontal plate 331, and the left side plate 301 and the right side plate 302 are respectively provided with mounting grooves 305 consistent with the cross sections of the two side edges of the slide plate 35. During installation, the side edges of the slide plate 35 are installed in the mounting grooves 305, so that the deformation of the slide cavity 34 during the adjustment of the experimental device can be avoided, and the adjustment accuracy can be improved.

[0061] In this embodiment, the inner surface profile of the flexible expansion section 33 is designed based on the Mach number of 2.5. The purpose of designing based on the Mach number of 2.5 is that when the Mach number is adjusted between 2.5 and 5, the working condition corresponding to 2.5 is the working condition when the throat cross-sectional area is maximum. In this way, during the adjustment of the Mach number, the rigid contraction section will always generate pressure on the flexible inlet transition section, forcing the inner surfaces of the flexible inlet transition section and the rigid contraction section to always form a smooth curved surface connection, avoiding separation. When the Mach number changes between 2.5 and 5, the translational movement of the throat will produce translation in left and right and up and down two dimensions. In order to ensure that the inner surface of the rigid contraction section 32 and the inner surface of the flexible expansion section 33 are continuously and smoothly connected during the movement, the flexible expansion section 33 will deform flexibly and simultaneously slide forward and backward along the direction defined by the slide cavity 34 under the action of the force transmitted by the throat.

[0062] Further, as shown in Figure 10 , Figure 11 the upper plate surface of the horizontal plate 331 is provided with a first sealing groove 3311, and a sealing rubber strip is installed in the first sealing groove 3311 for sealing between the horizontal plate 331 and the second flat plate 304; the lower plate surface of the horizontal plate 331 is provided with a second sealing groove 3312, and a sealing rubber strip is installed in the second sealing groove 3312 for sealing between the horizontal plate 331 and the slide plate 35. The side edge of the arc plate 332 is provided with a third sealing groove 3321 along the arc length direction of the arc plate 332, and a sealing rubber strip is installed in the third sealing groove 3321 for sealing between the flexible expansion section 33 and the left side plate 301 and the right side plate 302.

[0063] Further, as shown in Figure 11As shown, the joint of the arc-shaped plate 332 and the rigid contraction section 32 is connected and fixed by the transition plate 36, the transition plate 36 is a rigid plate and is connected to the outer surfaces of the rigid contraction section 32 and the arc-shaped plate 332, the inner surfaces of the flexible inlet transition section 31, the rigid contraction section 32 and the flexible expansion section 33 always form a smooth curved surface connection. The transition plate 36 transfers the stress concentration position from the joint gap of the rigid contraction section 32 and the flexible expansion section 33 to the overlapping position of the outlet end side surface of the flexible expansion section 33 corresponding to the transition plate 36, avoids the joint gap from increasing during the adjustment of the Mach number, and also plays a sealing role, making the experimental flow more stable.

[0064] Further, as shown in Figure 20 , the gear box 5 is also provided with a sealing cavity 8 fixed on the first flat plate 303, the left side plate 301 and the right side plate 302, the lower part of the sealing cavity 8 is open, and a closed space is formed between the sealing cavity 8 and the joint of the first flat plate 303 and the rigid contraction section 32 and the flexible inlet transition section 31. Since the flexible inlet transition section 31 is lapped on the inner surface of the rigid contraction section 32, the flexible inlet transition section 31 always closely fits the inner surface of the rigid expansion section 32 during movement, in order to increase the sealing effect, the sealing cavity 8 is provided on the periphery.

[0065] Further, as shown in Figure 18 , Figure 19 , the end face of the gear box 5 close to the sealing cavity 8 is open, the open end is provided with a sliding groove 51 matched with the rigid contraction section 32, and the open end and the end face close to the sealing cavity 8 are integrated and sealed. Specifically, a sealing groove 81 is arranged on the end face of the sealing cavity 8 close to the gear box 5, and a sealing strip is installed in the sealing groove 81 to realize the sealing between the sealing cavity 8 and the rigid contraction section 32. The sliding groove 51 is used to provide further positioning for the moving rigid contraction section 32.

[0066] Further, as shown in Figure 7 , Figure 8As shown, the outer surface of the rigid contraction section 32 at one end is provided with a rack 321, and a gear 52 engaging with the rack 321 is fixed in the gear box 5. The gear 52 is driven by a servo motor 53, and the servo motor 53 drives the rigid contraction section 32 to move horizontally along the direction defined by the sliding groove 51 through gear-rack transmission, so as to adjust the height of the throat. Meanwhile, the other end of the rigid contraction section 32 drives the flexible expansion section 33 to produce adaptive deformation and move horizontally along the inner plate surface of the second plate 304. The rigid contraction section 32 also drives the upstream flexible inlet transition section 31 to produce deformation when moving, so that the inner surfaces of the flexible inlet transition section, the rigid contraction section and the flexible expansion section always form a smooth curved surface connection, and the Mach number is dynamically changed. Specifically, the output shaft of the servo motor 53 is connected to the gear shaft 55 of the gear 52 through a coupling 54. The two ends of the gear shaft 55 are connected to the left side plate 301 and the right side plate 302 of the nozzle section 3 through bearings 56, respectively. The bearing cover 57 is arranged at the connection between the left side plate 301 and the bearing 56, so as to form a seal between the inner cavity of the gear box 5 and the outside. The bearing cover 58 is arranged at the connection between the right side plate 302 and the bearing 56, so as to form a seal between the inner cavity of the gear box 5 and the outside. The servo motor 53 and the coupling 54 are located outside the nozzle section 3, and the servo motor 53 is fixed on a motor mounting bracket 59 through a lifting frame 531. The lifting frame 531 can be used to adjust the installation height of the servo motor 53 during installation of the experimental device.

[0067] When the servo motor 53 receives the electrical signal of the signal processor 7, it starts to work. The servo motor 53 drives the gear shaft 55 and the gear 52 to rotate through the coupling 54. The gear shaft 55 is connected to the gear 52 in a key connection mode. The gear 52 engages with the rack 321 on the rigid contraction section 32, drives the rigid contraction section 32 to move along the direction defined by the sliding groove 51, i.e. drives the rigid contraction section 32 to move horizontally along the right inclined surface of the sealed cavity 8, and drives the servo motor 53 to rotate clockwise or counterclockwise according to the electrical signal of the signal processor 7, so as to increase or decrease the height of the throat, and further change the Mach number in the experimental section.

[0068] Further, the top of the gear box 5 is also sealingly connected with a laser displacement sensor 6, and the laser displacement sensor 6 is connected with a signal processor 7. The laser displacement sensor 6 can measure the distance of the ranging point of the rigid contraction section 32 in real time and convert it into the throat height in the signal processor 7, compare the height with the height of the throat in the nozzle section corresponding to the preset Mach number, and then send an electric signal to the power system to control the forward rotation, reverse rotation and start-stop of the servo motor 53, realize dynamic self-adjustment, so as to realize the precise dynamic adjustment of the Mach number of the experimental section. The signal processor 7 can manually adjust the Mach number of the incoming flow required to be realized in the experimental process. The signal processor 7, the laser displacement sensor 6 and the servo motor 53 form a feedback control system, the laser displacement sensor 6 measures the distance of the ranging point of the rigid contraction section 32 in real time and converts it into the throat height in the signal processor 7, compares the height with the height of the throat in the nozzle section corresponding to the preset Mach number, and then sends an electric signal to the servo motor 53 to control the servo motor 53 to realize dynamic self-adjustment, so as to realize the precise dynamic adjustment of the Mach number of the airflow in the experimental section 4.

[0069] Further, as shown in Figure 15 , the emitting end 61 of the laser displacement sensor 6 is located inside the gear box 5, and the ranging light path 63 emitted by the emitting end 61 is always consistent with the inclination of the chute 51. That is, the installation position of the laser displacement sensor 6 requires that the ranging light path 63 emitted by the emitting end 61 must be parallel to the inclination of the chute 51, so that the position of the ranging point 631 on the rigid contraction section 32 of the experimental device during the Mach number adjustment process is always not deviated, and the accuracy of the feedback signal of the receiving end 62 is ensured.

[0070] Further, as shown in Figure 12 , Figure 13 , Figure 14 , Figure 16 , Figure 17 , the laser displacement sensor 6 is placed in the sensor mounting sleeve 64 and is positioned by the L-shaped leg 65 provided at the bottom of the sensor mounting sleeve 64. Specifically, the sensor mounting sleeve 64 includes a sleeve body 641 sealingly connected with the top of the gear box 5 and an upper cover 642 sealingly connected with the top of the sleeve body 641, the bottom of the sleeve body 641 is open to ensure that the emitting end 61 and the receiving end 62 of the laser sensor are not blocked, the L-shaped leg 65 is fixed at one end of the bottom of the sleeve body 641, the data transmission line 66 of the laser displacement sensor 6 is connected with the signal processor 7 after passing through the upper cover 642, and the data transmission line 66 and the upper cover 642 are sealingly connected.

[0071] The working principle and working process of the present application are as follows:

[0072] The nozzle segment of the present application is designed under the condition that the Mach number of the flow in the experimental segment is 2.5, and this condition is the default experimental condition when the feedback control system is not started. After the experiment starts, the airflow enters the wind tunnel experimental device, and when the feedback control system is not started, the airflow with a Mach number of 2.5 will be generated at the experimental segment, and the experiment can be carried out at this time.

[0073] When the feedback control system is started, the feedback control system will be pre-calibrated, the laser displacement sensor measures the distance between the current emission end and the ranging point, and converts it into an electrical signal transmitted to the signal processor, and records the Mach number of the incoming flow at this moment. 2.5 experimental condition, that is, pre-calibration before adjustment. Set the Mach number in the required experimental segment in the signal processor, and the laser displacement sensor continues to measure the distance, and the measured distance signal is transmitted to the signal processor after processing to obtain the actual height of the throat at this time and obtain the actual Mach number corresponding to the electrical signal at this moment. The signal processor compares the electrical signals of the actual Mach number and the electrical signals of the required experimental Mach number, and transmits the electrical signals to the servo motor to control the rotation of the gear, and then drive the rigid contraction segment to move along the right side of the sealing cavity. The flexible inlet transition section deforms adaptively with the rigid contraction segment, and the flexible expansion section deforms adaptively with the rigid contraction segment 314 and slides in the slide cavity along the slide plate to change the throat height and realize the change of the incoming Mach number. During the adjustment process, the laser displacement sensor continues to work, and continuously transmits the signal to the signal processor, and the electrical signals of the actual Mach number and the electrical signals of the input Mach number are compared again. Feedback to the servo motor to control its forward rotation, reverse rotation or stop.

[0074] Further, the present application can also realize the continuous change of the Mach number during the experiment. The required incoming Mach number in the experimental segment can be increased or decreased in real time by the signal processor during the experiment, and the adjustment range is 2.5-5. After the experiment is finished, the signal processor is turned off, and the wind tunnel experimental device returns to the initial state.

[0075] The relationship between the distance measured by the laser displacement sensor 51 and the throat section height in the above principle is:

[0076] Hthroat=Hinitial(Hthickness+lsinα)×2

[0077] Wherein: H 喉 is the throat height; H 初 is the vertical height of the laser emission end and the center axis of the wind tunnel experimental device in the initial state; H 厚 is the vertical distance between the ranging point and the inside type plate convex point of the rigid contraction segment; l is the measured distance; α is the included angle between the ranging light path and the center axis of the wind tunnel experimental device.

[0078] The relationship between the experimental segment Mach number and the experimental segment cross-sectional area and the throat cross-sectional area in the above principle is:

[0079]

[0080] wherein A 出 is the exit cross-sectional area, i.e. the cross-sectional area of the test section; A 喉 is the throat cross-sectional area; r is the absolute pressure coefficient, which is taken as 1.4.

[0081] The following will be described in detail with reference to the embodiments. In the embodiments, the laser displacement sensor 6 is of the model Panasonic HG-C1400-P, the measurement center distance is 400 mm, and the measurement range is ±200 mm. The servo motor 53 is a servo motor of the model Panasonic MINAS A6 series MGMF092L1H5, the rated speed is 1500 rpm, and the rated power is 850 W.

[0082] Embodiment I:

[0083] When the feedback control system is not started, i.e. the wind tunnel experimental device is in the initial state, the gas source is connected to the contraction section, and the gas enters the internal flow passage of the wind tunnel experimental device, and after passing through the nozzle section, a gas coming flow with the required Mach number is generated in the test section.

[0084] At this time, the entire flow field Mach number cloud map is shown in Fig. 21(a), the variation curve of the Mach number corresponding to x=0.28 m along the y direction is shown in Fig. 21(b), and the corresponding nozzle section profile is shown in Fig. 21(c). The ratio of the test section area A 出 to the throat cross-sectional area A 喉 is 2.637, and the main flow zone Mach number is 2.5.

[0085] Embodiment II:

[0086] On the basis of Embodiment I, the feedback control system is started, and the feedback control system automatically completes the pre-calibration. The required Mach number of the test section is set to 3 in the signal processor, the laser displacement sensor continues to work, the measured distance signal is transmitted to the signal processor, and the actual height of the throat at this time is obtained after processing. The actual Mach number corresponding to the actual Mach number at this moment is obtained. The signal processor compares the electric signal of the actual Mach number with the electric signal of the required Mach number, and transmits the electric signal to the servo motor to control the rotation of the gear, thereby driving the rigid contraction section to move along the sliding groove. The flexible inlet transition section deforms adaptively with the rigid contraction section, and the flexible expansion section deforms adaptively with the rigid contraction section and slides along the sliding groove plate in the sliding groove cavity. The inner surfaces of the flexible inlet transition section, the rigid contraction section, and the flexible expansion section always form a smooth curved surface connection. The laser displacement sensor continues to work during the adjustment process, and continuously transmits the signal to the signal processor. The electric signal of the actual Mach number is compared with the electric signal of the input Mach number again, and is fed back to the servo motor to control the forward rotation, reverse rotation, or stop.

[0087] At this time, the entire flow field Mach number cloud map is shown in Fig. 22(a), the curve of Mach number corresponding to x = 0.28 m along the y direction is shown in Fig. 22(b), and the corresponding nozzle section profile is shown in Fig. 22(c). After adjustment, it can be seen that the height and cross-sectional area of the throat of this embodiment change, the cross-sectional area A 出 of the experimental section is 0.0008 m2, and the ratio of the cross-sectional area A 喉 of the experimental section to the cross-sectional area A 喉 of the throat is 4.235, and the main flow zone Mach number is 2.973.

[0088] Example Three:

[0089] On the basis of Example One and Example Two, the Mach number required by the experimental section in the signal processor is changed to 4, and the operations of Example One and Example Two are repeated. At this time, the entire flow field Mach number cloud map is shown in Fig. 23(a), the curve of Mach number corresponding to x = 0.28 m along the y direction is shown in Fig. 23(b), and the corresponding nozzle section profile is shown in Fig. 23(c). After adjustment, it can be seen that the height and cross-sectional area of the throat of this embodiment change, the cross-sectional area A 出 of the experimental section is 0.0024 m2, and the ratio of the cross-sectional area A 喉 of the experimental section to the cross-sectional area A 喉 of the throat is 10.719, and the main flow zone Mach number is 4.001.

[0090] Example Four:

[0091] On the basis of Example One and Example Two, the Mach number required by the experimental section in the signal processor is changed to 5, and the operations of Example One and Example Two are repeated. At this time, the entire flow field Mach number cloud map is shown in Fig. 24(a), the curve of Mach number corresponding to x = 0.28 m along the y direction is shown in Fig. 24(b), and the corresponding nozzle section profile is shown in Fig. 24(c). After adjustment, it can be seen that the height and cross-sectional area of the throat of this embodiment change, the cross-sectional area A 出 of the experimental section is 0.0024 m2, and the ratio of the cross-sectional area A 喉 of the experimental section to the cross-sectional area A 喉 of the throat is 25, and the main flow zone Mach number is 4.901.

[0092] In summary, during the experiment, on the basis of Example One and Example Two, the Mach number of the incoming flow gas in the experimental section in the signal processor is changed periodically, and the operations of Example One and Example Two are repeated, so that the dynamic adjustment of the Mach number of the incoming flow gas and the periodic change of the incoming flow gas in the experimental section can be realized.

[0093] The above-described embodiments are merely intended to describe the preferred embodiments of the present application, and are not intended to limit the scope of the present application. Various modifications and improvements to the present application made by those skilled in the art are intended to fall within the scope of the present application defined in the claims.

Claims

1. A variable Mach number wind tunnel test device based on rigid-flexible coupling deformation structure, comprising a wind tunnel sequentially connected by a contraction section (1), an inlet section (2), a nozzle section (3) and a test section (4), the internal flow passages of the contraction section (1), the inlet section (2), the nozzle section (3) and the test section (4) are sequentially communicated to form a gas flow passage of the wind tunnel, and the inlet end of the contraction section (1) is directly connected with a gas source, and the gas from the gas source enters the gas flow passage to form a target Mach number gas, characterized in that: The nozzle section (3) is rectangular as a whole, and is enclosed by left side plates (301) and right side plates (302) arranged symmetrically in the left-right direction, and upper cover assemblies and lower cover assemblies arranged symmetrically in the up-down direction; the upper cover assemblies and the lower cover assemblies each include a first flat plate (303) arranged close to the inlet section (2) and a second flat plate (304) arranged close to the experimental section (4); the outer surfaces of the first flat plate (303) and the second flat plate (304) are located in the same horizontal plane and have a gap therebetween, and the gap is connected to the gear box (5) in a sealed manner; ​ the internal flow channel of the nozzle section (3) is a contraction-expansion type flow channel, and is sequentially connected by flexible inlet transition sections (31), rigid contraction sections (32) and flexible expansion sections (33) arranged symmetrically in the up-down direction; the flexible inlet transition sections (31) are flexible plates, one end of which is in plug-in cooperation with the end of the first flat plate (303), and the other end of which is always lapped on the inner surface of the rigid contraction section (32); the rigid contraction sections (32) are rigid plates, one end of which is located in the gear box (5) and cooperates with a sliding groove (51) arranged in the gear box (5), and the other end of which is located in the nozzle section (3) and connected to the flexible expansion section (33); the sliding groove (51) is arranged in a vertical direction; the flexible expansion section (33) is a flexible plate, one end of which is in plug-in cooperation with the rigid contraction section (32), and the other end of which is in abutment with the inner plate surface of the second flat plate (304); the outer surface of one end of the rigid contraction section (32) located in the gear box (5) is provided with a rack (321), the gear box (5) is fixedly provided with a gear (52) engaged with the rack (321), the gear (52) is driven by a servo motor (53), the servo motor (53) drives the rigid contraction section (32) to move horizontally along the direction defined by the sliding groove (51) through gear and rack transmission to adjust the height of the throat, and the other end of the rigid contraction section (32) drives the flexible expansion section (33) to produce self-adaptive deformation and move horizontally along the inner plate surface of the second flat plate (304); the top of the gear box (5) is further sealed connected with a laser displacement sensor (6), the laser displacement sensor (6) is connected with a signal processor (7), and the emitting end (61) of the laser displacement sensor (6) is located in the gear box (5), and the inclination of the ranging light path (63) emitted by the emitting end (61) is always consistent with the inclination of the sliding groove (51).

2. The variable Mach number wind tunnel experimental apparatus based on rigid-flexible coupled morphing structure of claim 1, wherein: The side of the gear box (5) is further provided with a sealed cavity (8) fixed on the first flat plate (303), the left side plate (301) and the right side plate (302); the lower part of the sealed cavity (8) is open, and a closed space is formed between the sealed cavity (8) and the abutting part of the first flat plate (303), the rigid contraction section (32) and the flexible inlet transition section (31); the end face of the gear box (5) close to the sealed cavity (8) is open, the open end is provided with a sliding groove (51) matched with the rigid contraction section (32), and the open end and the end face close to the sealed cavity (8) are integrated and sealed.

3. The variable Mach number wind tunnel experimental apparatus based on rigid-flexible coupled morphing structure of claim 1, wherein: The laser displacement sensor (6) is placed in the sensor mounting sleeve (64) and positioned by the L-shaped support (65) arranged at the bottom of the sensor mounting sleeve (64), the sensor mounting sleeve (64) comprises a sleeve body (641) sealingly connected with the top of the gear box (5) and an upper cover (642) sealingly connected with the top of the sleeve body (641), the bottom of the sleeve body (641) is open to allow the emission end (61) and the receiving end (62) of the laser sensor not to be blocked, the L-shaped support (65) is fixed at one end of the bottom of the sleeve body (641), the data transmission line (66) of the laser displacement sensor (6) is connected with the signal processor (7) after passing through the upper cover (642), and the data transmission line (66) and the upper cover (642) are sealingly connected.

4. The variable Mach number wind tunnel experimental apparatus based on rigid-flexible coupled morphing structure of claim 1, wherein: The flexible expansion section (33) comprises a horizontal plate (331) and an arc-shaped plate (332), the rear half of the horizontal plate (331) is attached to the rear half of the arc-shaped plate (332) and connected as a whole, and an elastic opening is formed between the front half of the horizontal plate (331) and the front half of the arc-shaped plate (332); the front half of the horizontal plate (331) is located in the slide cavity (34) provided on the second flat plate (304), and the front half of the arc-shaped plate (332) is insertedly connected with the rigid contraction section (32).

5. The variable Mach number wind tunnel experimental apparatus based on rigid-flexible coupled morphing structure of claim 4, wherein: The inner plate surface of the second flat plate (304) is fixed with an L-shaped slide plate (35), the vertical plate surface of the slide plate (35) is fixed to the end surface of the second flat plate (304) close to the first flat plate (303), the horizontal plate surface of the slide plate (35) is parallel to the second flat plate (304) and has a spacing with the second flat plate (304), the spacing forms the slide cavity (34) for accommodating the front half of the horizontal plate (331), and the left side plate (301) and the right side plate (302) are respectively provided with mounting grooves (305) matching the cross sections of the two sides of the slide plate (35).

6. The variable Mach number wind tunnel experimental apparatus based on rigid-flexible coupled morphing structure of claim 4, wherein: The transition plate (36) is a rigid plate and is connected and fixed at the outer surfaces of the rigid contraction section (32) and the arc-shaped plate (332), and the inner surfaces of the flexible inlet transition section (31), the rigid contraction section (32) and the flexible expansion section (33) always form smooth curved surface connections.

7. The variable Mach number wind tunnel experimental apparatus based on rigid- flexible coupled morphing structure of claim 1, wherein: The output shaft of the servo motor (53) is connected with the gear shaft (55) of the gear (52) through a coupling (54), the two ends of the gear shaft (55) are connected with the left side plate (301) and the right side plate (302) of the nozzle section (3) through bearings (56), the left side plate (301) is provided with a bearing cover (57) for sealing the inner cavity of the gear box (5) and the outside, the right side plate (302) is provided with a bearing cover (58) for sealing the inner cavity of the gear box (5) and the outside, the servo motor (53) and the coupling (54) are located outside the nozzle section (3), and the servo motor (53) is fixed on the motor mounting frame (59) through a lifting frame (531).

8. The variable Mach number wind tunnel experimental apparatus based on rigid- flexible coupled morphing structure of claim 1, wherein: The internal flow channel of the contraction section (1) is a variable-diameter flow channel with a circular inlet section and a rectangular outlet section, the internal flow channel of the air inlet section (2) is a rectangular flow channel, the internal flow channel of the nozzle section (3) is a contraction-expansion type flow channel, and the internal flow channel of the experimental section (4) is a rectangular flow channel; the contraction section (1), the air inlet section (2), the nozzle section (3) and the experimental section (4) are connected through flanges.

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