A landing gear scale model device for pneumatic noise wind tunnel test and a MEMS microphone array test method

Abstract

The application discloses a landing gear scale model device for pneumatic noise wind tunnel test and a MEMS microphone array test method. A small wind tunnel is selected to build a pneumatic acoustic test platform. In the test platform, an end plate is installed on the side of the wind tunnel nozzle, the end plate is embedded with a rotating platform, and the scale landing gear model arranged in the wind tunnel is connected through the rotating platform. Meanwhile, an arc array is installed through the erection of a cross beam in the overhead and side direction of the landing gear, the posture of the arc array is adjusted, the plane of the side arc array is parallel to the horizontal plane, the plane of the overhead arc array is perpendicular to the axis of the cross beam, the center of the arc array is coplanar with the center of the scale landing gear model, and the MEMS microphone is installed on the arc needle array. Then, according to the standard test method, the scale landing gear model is subjected to pneumatic acoustic wind tunnel array measurement test. The application can meet the requirements of model installation in a small-size wind tunnel, a high-quality pneumatic acoustic field environment and high-density array movable collection points for realizing spatial directivity measurement.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of landing gear aerodynamic noise testing, and particularly relates to a landing gear scale model device for aerodynamic noise wind tunnel testing and a MEMS microphone array testing method. BACKGROUND

[0002] With the rapid development of the civil aviation industry, the problem of aircraft noise has become a problem that the aviation industry pays more and more attention to. The noise level of a civil aircraft has a very direct relationship with the airworthiness certification and market competitiveness of the civil aircraft. For a modern large passenger aircraft, the landing gear is the most important type of aircraft noise source. The mechanism of landing gear aerodynamic noise is an important means to understand the generation, evolution and distribution of landing gear noise, and a simplified landing gear model is a very important theoretical research means. The experimental study of the noise characteristics of the landing gear is generally carried out in an aerodynamic acoustic wind tunnel. Considering that the full-size model in the wind tunnel experiment has a high cost and a long cycle, scale experimental research is a more cost-effective and operable choice.

[0003] Although there are mature technical standards and specifications for the setting of the acoustic environment of the test section of the wind tunnel and the wind tunnel test method of the measured object in the industry at present, in the widely used noise measurement method, the free-field microphone sensor is expensive, and due to the complicated disassembly process of the large-size landing gear model and the difficulty in correcting the position, it brings great time and economic cost. SUMMARY

[0004] In view of the problems in the above-mentioned prior art background, a new type of landing gear scale model device for aerodynamic noise wind tunnel testing and a MEMS microphone array collection method are proposed, which can meet the model installation under a small-size wind tunnel, a high-quality aerodynamic sound field environment, and a high-density array movable collection point to realize spatial directivity measurement.

[0005] The landing gear scale model device for aerodynamic noise wind tunnel testing of the application comprises a single-sided end plate and a rotating base, a scale landing gear model, a circular arc array, a T-shaped slot slide rail array support, a MEMS micro-electro-mechanical system and an array microphone.

[0006] The single-sided end plate is arranged in the wind tunnel test section and fixed to the side of the single-sided wind tunnel nozzle. A through hole is formed in the center of the end plate for penetrating the rotating base.

[0007] The rotating axis of the rotating base is arranged horizontally, penetrates the center through hole of the end plate, and is connected with the scale landing gear model located in the wind tunnel. The rotating base and the through hole are sealed, and the inner wall surface of the end plate is flat.

[0008] The T-shaped slot slide rail array support comprises two mutually perpendicular T-shaped cross beams, which are a side beam arranged along the flow direction at the side of the test section of the wind tunnel and a top beam arranged above the test section of the wind tunnel; the side beam and the top beam are opposite to the center of the scaled landing gear, and a T-shaped sliding groove is arranged at the center position of the side beam and the top beam to install the circular arc array.

[0009] The circular arc array is an arc structure, and the center of the outer arc surface is installed and fixed by a T-shaped nut matched with the T-shaped sliding groove on the two cross beams; the distance between the circular arc array and the scaled landing gear model is adjustable. Meanwhile, the plane where the clamping parts of the circular arc array on the side beam are arranged is parallel to the horizontal plane, the plane where the clamping parts of the circular arc array on the top beam are arranged is perpendicular to the axis of the top beam, and the centers of the clamping parts of the two circular arc arrays are coplanar with the center of the scaled landing gear model.

[0010] The inner arc surface of the circular arc array is designed with clamping grooves at equal intervals to install MEMS microphones; the MEMS microphone sensors are fixed by being clamped into the clamping grooves through a gasket.

[0011] The MEMS micro-electro-mechanical system is started outside the wind tunnel, connected with the MEMS microphones, and can directly transmit data to a computer to process the data into understandable noise spectrum for analysis.

[0012] The method for performing MEMS microphone array test by using the landing gear scaled model device for aerodynamic noise wind tunnel test is as follows:

[0013] Step one: a small wind tunnel is selected according to the 1 / 10 scaled size to build an aerodynamic acoustic test platform, and a single-sided end plate is installed on one side of the wind tunnel nozzle.

[0014] Step two: a rotating base rotating end center mounting stud is installed, the rotating base is further installed on an external lifting platform, the axis of the rotating base is parallel to the horizontal plane, and the rotating base and the external lifting platform are moved to the outside of the end plate.

[0015] Step three: the vertical height of the rotating base is adjusted by controlling the external lifting platform, and the rotating base is aligned with the through hole formed in the center of the end plate.

[0016] Step four: the bottom of the scaled landing gear model is passed through the center hole of the end plate from the inside of the end plate, and the bottom hole is screwed and fixed with the front end of the stud.

[0017] Step five: the scaled landing gear model is leveled.

[0018] Step six: the position of the external lifting platform is horizontally moved, the rotating end of the rotating base is inserted into the through hole formed in the center of the end plate, and the end surface of the rotating base is lower than the inner side surface of the end plate, and then the position of the external lifting platform is fixed.

[0019] Step seven: fill the gap between the end face of the rotating base and the inner side of the end plate with modeling clay after slight heating, and then scrape it flat with a flat tool to make the blocking part flush with the inner side of the end plate.

[0020] Step eight: build a T-shaped slide rail array support.

[0021] A rectangular frame is built around the entire wind tunnel test platform, which has side beams designed along the airflow direction on the side facing the inner side of the end plate, and top beams designed perpendicular to the airflow direction on the top surface. Further adjust the horizontal position of the rectangular frame so that the side beams and the top beams are directly opposite the center of the scaled landing gear.

[0022] Step nine: install the overtop and side direction circular arc array.

[0023] Insert the nut of the T-shaped bolt in the T-shaped slide groove in the circular arc array; further adjust the position of the circular arc array along the horizontal laser beam by aligning the center of the scaled landing gear model with the laser beam emitted in the direction perpendicular to the axis of the beam on which the circular arc array is located. Then adjust the position of the circular arc array along the T-shaped slide groove so that the center of the circular arc array reaches the position of the laser beam, complete the position adjustment of the circular arc array, and then tighten and lock to complete the installation of the circular arc array, so that the center of the circular arc array is coplanar with the center of the scaled landing gear model.

[0024] Step nine: install the MEMS microphone in the clamping groove on the clamping piece in each circular arc array.

[0025] Step ten: rotate the circular arc array so that the plane on which the clamping piece on the side beam is located is parallel to the horizontal plane, and the plane on which the clamping piece on the top beam is located is perpendicular to the axis of the top beam.

[0026] Step eleven: according to the standard test method known in the field of aeroacoustic wind tunnel test, conduct aeroacoustic wind tunnel array measurement test on the scaled landing gear model to independently obtain the overall noise data, noise spectrum characteristics, sound source spatial directivity and other aeroacoustic characteristics information of the current model.

[0027] The advantages of the present application are:

[0028] The landing gear scaled model device and MEMS microphone array test method for aeroacoustic wind tunnel test can meet the requirements of model installation in small size wind tunnel, high quality aeroacoustic field environment, high density array movable collection point, and realize spatial directivity measurement. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The present application is a schematic diagram of the overall structure of the landing gear scaled model device for aeroacoustic wind tunnel test.

[0030] Figure 2It is the side view schematic diagram of end plate structure in landing gear scale model device for aerodynamic noise wind tunnel test of the application;

[0031] Figure 3 It is the front view schematic diagram of end plate structure in landing gear scale model device for aerodynamic noise wind tunnel test of the application;

[0032] Figure 4 It is the schematic diagram of end plate and landing gear connection structure;

[0033] Figure 5 It is the schematic diagram of circular arc array installation mode in landing gear scale model device for aerodynamic noise wind tunnel test of the application;

[0034] Figure 6 It is the schematic diagram of circular arc array structure in landing gear scale model device for aerodynamic noise wind tunnel test of the application;

[0035] Figure 7 It is the schematic diagram of circular arc array structure section in landing gear scale model device for aerodynamic noise wind tunnel test of the application;

[0036] Figure 8 It is the result collected in Beihang D7 wind tunnel by using the device and method of the application;

[0037] Figure 9 It is the directivity of landing gear side edge far field noise under different incoming flow Mach numbers

[0038] In the figure:

[0039] 1-single end plate 2-rotary base 3-scale landing gear

[0040] 4-circular arc array 5-T-shaped groove slide rail array support 101-end plate

[0041] 102-side plate 201-stud 401-detent

[0042] 402-telescopic structure 403-T-shaped nut 501-side beam

[0043] 502-top beam 503-T-shaped slide groove DETAILED DESCRIPTION

[0044] The application will be further described in detail below in combination with the drawings.

[0045] The landing gear scale model device for aerodynamic noise wind tunnel test of the application is built in the wind tunnel anechoic chamber, including single end plate 1, rotary base 2, scale landing gear model (LAGOON 1 / 10 scale international standard model) 3, circular arc array 4, T-shaped groove slide rail array support 5, MEMS micro-electro-mechanical system and array microphone, as shown in Figure 1 .

[0046] The single-sided end plate 1 is arranged in the wind tunnel test section, i.e. between the nozzle diameter and the collection diameter of the wind tunnel, for creating a good aerodynamic sound field environment, increasing the effective shear layer area and noise collection effect, and is designed as an L-shaped structure composed of an end plate 101 and a side plate 102, as shown in Figure 2 The material is preferably transparent plywood, which is arranged perpendicular to the building platform.

[0047] In the single-sided end plate 1, the side plate 102 is fixedly connected to the side end surface of the nozzle diameter of the wind tunnel through screws, so that the bottom edge of the end plate 101 is equal to the vertical distance between the bottom edge of the wind tunnel diameter and the building platform, and the top edge of the end plate is flush with the top edge of the wind tunnel diameter; the inner side of the end plate 101 is flush with the inner wall of the nozzle diameter.

[0048] The thickness of the end plate 101 is preferably 1 / 2 of the thickness of the wind tunnel, and the transverse length is greater than 1 / 2 of the wind tunnel test section, so that the side of the wind tunnel test section is not completely sealed, and the lifting platform is arranged conveniently. The center of the end plate 101 is provided with a through hole for penetrating the rotary base 2, as shown in Figure 3 .

[0049] The rotary base 2 cooperates with the external lifting platform to realize the leveling and rotation of the scaled landing gear model 3. The rotary axis of the rotary base 2 is arranged horizontally and fixedly installed on the external lifting platform to form an integral body, which is arranged outside the end plate 101. Thus, the height of the rotary base 2 can be adjusted to be consistent with the height of the center opening of the end plate 101 by the external lifting platform, and the rotary base 2 can be aligned with the center opening of the end plate 101 by further moving the external lifting platform. As shown in Figure 4 The rotary end of the rotary base 2 has an M6 threaded hole, which is screwed and fixed with the end of the stud 201 through thread cooperation. The scaled landing gear model 3 is placed inside the end plate 101, and after penetrating through the center through hole of the end plate 101, the bottom M6 hole is screwed and fixed with the front end of the stud 201 through thread cooperation.

[0050] Thus, the rotary base 2 and the external lifting platform can provide the application of the scaled landing gear model 3 under variable angle of attack conditions. Due to the wind tunnel experiment, the wheels need to be completely horizontally aligned with the flow direction of the wind tunnel, and slight inclination will cause the noise data to change, which cannot achieve the expected effect corresponding to the working condition. Therefore, the angle of attack angle is determined by corresponding the angle scale (positive and negative 180 degrees, the leveling position is 0 degrees) on the rotary base 2. During calibration, a horizontal instrument is placed on the wheels of the scaled landing gear model 3 through a flat plate, and the scale is adjusted to 0 degrees while the horizontal instrument accuracy display error is 0.05, which represents the leveling of the scaled landing gear model 3. The variable angle of attack application is preferably -10-10 degrees after actual operation test (measured by the rotary base 2 and the horizontal instrument).

[0051] After the scaled landing gear model 3 is leveled, the rotating end of the rotating base 2 is inserted into the central opening of the end plate 101 by horizontally moving the external lifting platform, and the end surface of the rotating base 2 is lower than the inner side surface of the end plate 101, and at this time the scaled landing gear model 3 is in the wind tunnel test section. Further, the small hole plugging technology is used between the end plate 101 and the end surface of the rotating base 2. After the modeling clay is slightly heated, it is filled into the screw holes, studs 201 and the reserved position of the end plate 101 (i.e. the gap between the end surface of the rotating base 2 and the inner side surface of the end plate 101), and finally the surface of the plugged part is leveled and smoothed with a flat tool, so that the surface of the plugged part is flush with the inner side wall of the end plate 102, in order to optimize the flow-induced noise and reduce the interference of unknown noise.

[0052] The T-shaped slot slide rail array support 5 includes two mutually perpendicular rectangular cross-section beams in T shape, two beams are respectively a side beam 501 arranged along the flow direction on the side of the wind tunnel test section, and a top beam 502 above the wind tunnel test section; both can be beams on the side and top surfaces supported by the frame built on the periphery of the wind tunnel. The center positions of the side beam 501 and the top beam 502 are opposite to the center of the scaled landing gear 3, and T-shaped sliding grooves 503 are designed on the side of the two beams facing the center position of the side wall of the scaled landing gear 3 along the direction perpendicular to the axial direction of the beam, for installing the circular arc array 4, as shown in Figure 5 .

[0053] The above two beams ensure the realization of spatial directivity measurement experiment, that is, the sound source intensity in three-dimensional coordinates can be captured through collection points at different positions. In theory, a simultaneous measurement at the intersection of the axle of the scaled landing gear model 3 and the axis of the stud 202 in the side and over-the-top direction of the scaled landing gear model 3 can achieve this purpose.

[0054] As shown in Figure 6 , the circular arc array 4 includes a clamping part 401, a sleeve 402, a locking bolt 403 and a T-shaped nut 404. The clamping part 401 is a circular arc structure, and a hole is formed in the center position of the outer arc surface. The clamping part 401 is slidably sleeved at the front part of the sleeve 402 through the hole, so that the clamping part 401 can slide along the axial direction of the sleeve 402. The rear part of the sleeve 402 is sleeved on the T-shaped nut 404, and the two are connected through a rotating bearing. The T-shaped nut 404 is threadedly connected with the T-shaped bolt 403.

[0055] The nut of the T-shaped bolt 403 is placed in the T-shaped sliding groove 503, and the nut of the T-shaped bolt 403 is designed to be attached to the two sides of the T-shaped sliding groove, thereby limiting the rotation of the T-shaped bolt 403 in the circumferential direction, and further tightening the T-shaped nut 404 to make the locking bolt 403 tightly contact in the T-shaped sliding groove 503; the movement of the T-shaped nut 404 is separated from the sleeve 402 by the rotating bearing, so that the sleeve 402 and the T-shaped nut can rotate independently. Therefore, after the T-shaped nut is tightened, the two clamping pieces 401 can be adjusted by rotating the clamping pieces 401, and the plane angle of the two clamping pieces 401 is adjusted. In the present application, the plane of the clamping pieces 401 in the arc array 4 on the side beam is parallel to the horizontal plane before the test, and the plane of the clamping pieces 401 on the top beam 502 is perpendicular to the axis of the top beam.

[0056] Before the T-shaped nut is tightened, the position of the arc array along the T-shaped sliding groove 503 needs to be adjusted, so that the centers of the clamping pieces 401 in the two arc arrays 4 and the center of the scaled landing gear model 3 are coplanar. After the T-shaped nut is tightened, the distance between the scaled landing gear model 3 and the sleeve 402 can be adjusted by adjusting the position of the clamping piece 401 in the axial direction of the sleeve 402, so as to facilitate the substitution of the noise conversion formula in the experiment.

[0057] The clamping pieces 401 in the two arc arrays 4 are designed with nine clamping grooves on the inner arc surface at equal intervals for installing MEMS microphones. Since the MEMS microphone sensor is very sensitive, it cannot be fixed by clamping. Therefore, the clamping groove is designed to allow the microphone to be clamped into the clamping groove to achieve fixation. Specifically, the diameter of the clamping groove is designed to be slightly larger than the diameter of the microphone sensor, so that the microphone can be clamped into the clamping groove by wrapping a sponge outside the microphone. At the same time, the design of the clamping groove facilitates the wiring of the MEMS microphone, and the data line of the microphone can be connected to the MEMS micro-electro-mechanical system outside the wind tunnel from the back side of the clamping piece 401, so that the data line will not fall into the wind field. Since the microphone integration is not necessarily 18 bits, more or fewer clamping grooves can be designed on the clamping piece 401 based on different experiments to change the density of the MEMS microphone. Therefore, clamping pieces 401 with various numbers of clamping grooves and various arc shapes can be designed to be replaced according to actual experimental requirements to change the measurement conditions.

[0058] The MEMS micro-electro-mechanical system mainly consists of an acoustic-electric conversion device, an amplifier, an analog-to-digital converter, etc., and has the advantages of small size and low price. It is started outside the wind tunnel, and the microphone is directly connected to it, and the data can be directly transmitted to the computer for processing by the matching platform to obtain understandable noise spectrum for analysis.

[0059] The MEMS microphone considers the cost performance, operability and integration capability, and selects a 32-element discrete array kit with the model WMM7035DTFN0, the sensitivity is 26±1 dBFS, the signal-to-noise ratio is 65 dB, and the maximum acoustic input is 120dBSPL. In the application, other model microphone array sound source positioning systems can be selected.

[0060] The method for array measurement test by using the landing gear scale model device for aerodynamic noise wind tunnel test of the application includes the following steps:

[0061] Step one: according to the 1 / 10 scale size, a small wind tunnel is selected to build an aerodynamic acoustic test platform, including the installation of a single-sided end plate 1. Before starting the formal test, the baseline working condition background noise needs to be measured to meet the technical standard requirements known in the field of wind tunnel construction.

[0062] Step two: install the rotating base 2 rotating end center mounting stud 201, further install the rotating base 2 on the external lifting platform, make the rotating base 2 axis parallel to the horizontal plane, and move them together to the outside of the end plate 101;

[0063] Step three: adjust the vertical height of the rotating base 2 by controlling the external lifting platform, and align the rotating base 2 with the center hole of the end plate 101.

[0064] Step four: after the bottom of the scale landing gear model 3 passes through the center hole of the end plate 101 from the inside of the end plate 101, the bottom M6 hole position thread cooperates with the front end thread of the stud 201 and is tightened and fixed.

[0065] Step five: use a level to place a flat plate on the wheel of the scale landing gear model 3, adjust the rotating base 2 scale to 0 degrees while the level accuracy display error is 0.05, and at this time the scale landing gear model 3 is leveled.

[0066] Step six: horizontally move the position of the external lifting platform, make the rotating end of the rotating base 2 pass into the through hole opened in the center of the end plate, and make the end surface of the rotating base 2 lower than the inside surface of the end plate 101, at this time fix the position of the external lifting platform.

[0067] Step seven: use the small hole plugging technology to fill the part between the end surface of the rotating base 2 and the inside end surface of the end plate 101 by slightly heating the modeling clay, and use the flat plate tool to scrape and repair the shape, so that the surface of the plugged part is flush with the inside wall surface of the end plate 102.

[0068] Step eight: build a T-shaped slide rail array support.

[0069] A rectangular frame is built around the whole wind tunnel test platform, which has side beams 501 designed along the airflow direction on the side facing the inner side of the end plate 101, and top beams 502 designed perpendicular to the airflow direction on the top surface; the horizontal position of the rectangular frame is further adjusted so that the center positions of the side beams 501 and the top beams 502 are opposite to the center of the scaled landing gear 3.

[0070] Step nine: installation of the overtop and side direction circular arc array 4 is performed.

[0071] The screw nuts of the T-shaped bolts 403 in the circular arc array 4 are inserted into the T-shaped sliding grooves 503; further, the laser range finder is used to emit laser along the horizontal direction perpendicular to the axis direction of the beam on which the circular arc array 4 is located, and the center of the scaled landing gear model 3 is aligned; then the position of the circular arc array 4 is adjusted along the T-shaped sliding groove 503 so that the center of the circular arc array 4 reaches the position of the laser, the position adjustment of the circular arc array 4 is completed, then the installation of the circular arc array 4 is completed by tightening and locking, so that the center of the clamping part 401 in the circular arc array 4 is coplanar with the center of the scaled landing gear model 3.

[0072] Step nine: the MEMS microphone is installed in the clamping groove on the clamping part 401 in each circular arc array 4, and the data line of the MEMS microphone is connected by winding around the back side of the clamping groove.

[0073] Step ten: the plane on which the clamping part 401 in the circular arc array 4 on the side beam is parallel to the horizontal plane by rotating the clamping part 401, and the plane on which the clamping part 401 on the top beam 502 is perpendicular to the axis of the top beam.

[0074] Step eleven: according to the standard test method known in the field of aeroacoustic wind tunnel test, the aeroacoustic wind tunnel array measurement test of the scaled landing gear model 3 is performed, and the overall noise data, noise spectrum characteristics, sound source spatial directivity and other aeroacoustic characteristics information of the current model are independently obtained.

[0075] As shown in the figure, Figure 8 the results collected in the Beihang D7 wind tunnel using the device and method of the present application can be seen, which can capture clear discrete peaks, and the sound pressure level meets the expected results. At the same time, Figure 9 the directivity of the landing gear side edge far-field noise under different incoming flow Mach numbers is also shown, and it can be seen that the directivity curves under different wind speeds are consistent.

Claims

1. A landing gear scale model apparatus for use in aeroacoustic wind tunnel testing, characterised in that: Single-sided end plate and rotating base, scaled landing gear model, circular array, T-shaped slot slide rail array support, MEMS micro-electro-mechanical system and array microphone; The single-sided end plate is arranged in the wind tunnel test section and is fixed to the side of the single-sided wind tunnel nozzle. A through hole is formed in the center of the end plate for inserting the rotating base. The single-sided end plate is an L-shaped structure composed of an end plate and a side plate. The side plate is fixedly connected to the end face of the side of the nozzle of the wind tunnel by screws. The vertical distance between the bottom edge of the single-sided end plate and the bottom edge of the wind tunnel to the building platform is equal to the vertical distance between the top edge of the end plate and the top edge of the wind tunnel. The inner side of the end plate is flush with the inner wall of the nozzle. The thickness of the end plate is preferably 1 / 2 of the thickness of the wind tunnel, and the horizontal length is greater than 1 / 2 of the length of the wind tunnel test section, so that the side of the wind tunnel test section is not completely sealed. The rotating axis of the rotating base is horizontally arranged and connected to the scaled landing gear model in the wind tunnel after being inserted into the through hole in the center of the end plate. The rotating base and the through hole are sealed, and the inner wall of the end plate is flat. The end face of the rotating base is lower than the inner side of the end plate after the rotating base is inserted into the through hole in the center of the end plate. Small hole sealing technology is used to fill the gap between the end plate and the end face of the rotating base after the modeling clay is slightly heated to achieve sealing and filling of the inner wall of the end plate. The T-shaped slot slide rail array support includes two T-shaped cross beams perpendicular to each other, which are a side beam arranged along the flow direction on the side of the wind tunnel test section and a top beam arranged above the wind tunnel test section. The center of the side beam and the center of the top beam are opposite to the center of the scaled landing gear, and a T-shaped slide groove is designed at the center position for installing the circular array. The circular array is an arc structure, and the center of the outer arc surface is fixed by a T-shaped bolt and a nut in the T-shaped slide groove of the two cross beams. The distance between the circular array and the scaled landing gear model is adjustable. The plane where the clamping part of the circular array on the side beam is parallel to the horizontal plane, and the plane where the clamping part of the circular array on the top beam is perpendicular to the axis of the top beam. The centers of the clamping parts of the two circular arrays and the center of the scaled landing gear model are coplanar. The specific structure of the circular array includes a clamping part, a sleeve, a locking bolt and a T-shaped nut. The clamping part is a circular arc structure with a hole in the center of the outer arc surface. The hole is slidably connected to the front part of the sleeve, so that the clamping part can slide along the axis of the sleeve. The rear part of the sleeve is connected to the T-shaped nut through a rotating bearing. The T-shaped nut is connected to the T-shaped bolt through a thread. The nut of the T-shaped bolt is placed in the T-shaped slide groove, and the nut is tightly fitted on both sides of the T-shaped slide groove, thereby limiting the rotation of the T-shaped bolt in the circumferential direction. Further tightening the T-shaped nut makes the locking bolt tightly fit in the T-shaped slide groove. After the T-shaped nut is tightened, the angle of the plane where the circular array is located is adjusted by rotating the circular array. The inner arc surface of the circular array is designed with equally spaced clamping grooves for installing MEMS microphones. The MEMS microphone sensor is fixed by being clamped into the clamping groove through a gasket. The MEMS micro-electro-mechanical system is started outside the wind tunnel, connected to the MEMS microphone, and can directly transmit data to the computer for processing to obtain understandable noise spectrum for analysis.

2. The landing gear scale model apparatus for use in aeroacoustic wind tunnel testing of claim 1, wherein: The rotating end center of the rotating base is fixed by screwing the threaded hole with the threaded end of the stud, and the bottom of the scaled landing gear model is fixed by screwing the threaded hole with the front end of the stud.

3. The landing gear scale model apparatus of claim 1, wherein: The two beams in the T-shaped slot slide rail array support are designed as beams on the side and top surfaces of the frame support built on the periphery of the wind tunnel.

4. The MEMS microphone array test method using the landing gear scale model device for aeroacoustic wind tunnel test of claim 1, wherein: The specific steps are as follows Step one: according to the 1 / 10 scaled size, select a small wind tunnel to build a pneumatic acoustic test platform, install a single-sided end plate on one side of the wind tunnel nozzle; Step two: install the rotating end center of the rotating base on the stud, and further install the rotating base on the external lifting platform, so that the rotating base axis is parallel to the horizontal plane, and both are moved to the outside of the end plate; Step three: adjust the vertical height of the rotating base by controlling the external lifting platform, so that the rotating base is aligned with the through hole opened in the center of the end plate; Step four: pass the bottom of the scaled landing gear model from the inside of the end plate through the center hole of the end plate, and screw the bottom hole with the front end of the stud; Step five: level the scaled landing gear model; Step six: horizontally move the position of the external lifting platform, so that the rotating end of the rotating base penetrates into the through hole opened in the center of the end plate, and the end surface of the rotating base is lower than the inside surface of the end plate, at this time, the position of the external lifting platform is fixed; Step seven: fill the part between the end surface of the rotating base and the inside end surface of the end plate with modeling clay after slight heating, and scrape and smooth the surface with a flat tool, so that the surface of the sealing part is flush with the inside wall surface of the end plate; Step eight: build a T-shaped slide rail array support; Build a rectangular frame around the entire wind tunnel test platform, which has side beams designed along the airflow direction on the side facing the inside of the end plate, and top beams designed perpendicular to the airflow direction on the top surface; further adjust the horizontal position of the rectangular frame, so that the center positions of the side beams and the top beams are opposite to the center of the scaled landing gear; Step nine: install the overtop and side direction circular arc array; Insert the nut of the T-shaped bolt in the circular arc array into the T-shaped slide groove; further adjust the position of the circular arc array along the horizontal direction of the beam axis perpendicular to the circular arc array being adjusted, align the center of the scaled landing gear model, and emit laser along the horizontal direction; then adjust the position of the circular arc array along the T-shaped slide groove, so that the center of the circular arc array reaches the position of the laser, complete the position adjustment of the circular arc array, then tighten and lock to complete the installation of the circular arc array, so that the center of the circular arc array is coplanar with the center of the scaled landing gear model; Step nine: install the MEMS microphone in the clamping groove on the clamping piece in each circular arc array; Step ten: rotate the circular arc array so that the plane where the clamping piece on the side beam is located is parallel to the horizontal plane, and the plane where the clamping piece on the top beam is located is perpendicular to the axis of the top beam; Step eleven: according to the standard test method known in the field of pneumatic acoustic wind tunnel test, conduct pneumatic acoustic wind tunnel array measurement test on the scaled landing gear model, independently obtain the overall noise data, noise spectrum characteristics, sound source spatial directivity and other pneumatic acoustic characteristics information of the current model.

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