Surface pulsating pressure wave number domain beam forming array wind tunnel measurement device and installation method

Abstract

The invention discloses a surface pulsating pressure wave number domain beam forming array wind tunnel measurement device and an installation method, relates to the field of wind tunnel tests, and is used for improving the surface pulsating pressure two-dimensional wave number domain beam forming test capability in the field of wind tunnel tests. A plurality of through holes arranged in an array are distributed in the skin, the array comprises a plurality of uniform annular arrays concentric from inside to outside and a plurality of spiral support arm arrays formed by the annular arrays from inside to outside, the FPC is provided with the through holes corresponding to the skin, each through hole is internally provided with an MEMS sensor, and the MEMS sensor is connected with the FPC. The MEMS sensor and a resistance pad on the skin are welded into a whole, and a pin of the MEMS sensor is welded on the FPC; according to the invention, the skin and the FPC circuit board can be prevented from tensile deformation caused by external stress; the bending degree of the array can be kept to be better attached to the measured curved surface, the lower surface of the filled array is in a flush state, and the shape preserving effect of the array measuring surface is facilitated.

Description

Technical Field

[0001] The invention relates to the field of wind tunnel tests, and in particular to a surface pulsating pressure wave number domain beamforming array wind tunnel measuring device and an installation method. Background Art

[0002] The pulsating pressure of the surface turbulent boundary layer is a very concerned issue in the field of fluid mechanics. On the one hand, it will directly radiate noise outward, and on the other hand, it will cause flow-induced vibration of the wall structure and form a secondary sound source. Therefore, it has received great attention in engineering practice fields such as aircraft, high-speed railways, and submarines. Wind tunnel model tests are an important means to obtain the characteristics of the pulsating pressure of the surface turbulent boundary layer. Among them, the two-dimensional wavenumber domain beamforming measurement can effectively support the acquisition of the relevant pulsating pressure wavenumber-frequency spectrum. In particular, the wavenumber domain beamforming has good adaptability to the entire wavenumber band, and can realize the synchronous measurement of different features such as the acoustic zone and the migration ridge zone. Under the same number of measurement array points, the wavenumber domain beamforming technology has a stronger applicability to the full wavenumber band for pulsating pressure measurement. To carry out two-dimensional wavenumber domain beamforming measurement of the model surface pulsating pressure, a two-dimensional surface array measurement device is required. The existing devices have the following shortcomings: 1. There is a lack of special surface array devices, and the existing methods mainly use single-point sensors to arrange and build them by themselves; 2. The integration of array elements is not high, and it is impossible to achieve high spatial distribution law sampling on the surface; 3. There is a lack of special array formation design methods, and it is impossible to improve the two-dimensional wave number domain beamforming measurement capability in a targeted manner. In summary, there is still a lack of an array measurement device specifically used for two-dimensional wave number domain beamforming of pulsating pressure on the surface of wind tunnel models. Summary of the invention

[0003] The purpose of the present invention is to design a measuring device to improve the two-dimensional wavenumber domain beamforming testing capability of surface pulsating pressure in the field of wind tunnel testing in view of the deficiencies of existing measuring equipment.

[0004] In order to achieve the above object, the present invention adopts the following technical solution: The surface pulsation pressure wave number domain beamforming array wind tunnel measuring device comprises a skin, on which a plurality of through holes arranged in an array are distributed, the array comprises a plurality of uniform annular arrays concentric from the inside to the outside, and a plurality of spiral arm arrays formed by the annular arrays from the inside to the outside, and a soldering plate is coaxially arranged on the outer side of each through hole on the welding surface of the skin, A bendable FPC is arranged under the skin, and the FPC is provided with through holes corresponding to the through holes on the skin one by one. A MEMS sensor is arranged in each through hole on the FPC, and a coaxial solder resist pad is arranged outside the pressure measuring hole after the pressure measuring hole of the MEMS sensor passes through the FPC through hole. The skin and the MEMS sensor are welded together through the solder resist pad, and the MEMS sensor is electrically connected to the FPC. An adapter board connected to the circuit on the FPC, wherein an IEPE power supply circuit is arranged on the adapter board and is independently connected to each MEMS sensor.

[0005] In the above technical solution, the solder resist pad is arranged between the skin and the FPC, the MEMS sensor and the skin are welded together through the solder resist pad, and the circuit pins of the MEMS sensor are welded to the circuit on the FPC.

[0006] In the above technical solution, a packaging layer is provided on the welding surface of the FPC, and the packaging layer seals the MEMS sensor and the surface of the FPC into one.

[0007] In the above technical solution, the FPC is connected to the skin as a whole.

[0008] In the above technical solution, the pressure measuring hole of the MEMS sensor is aligned with the center of the through hole of the corresponding skin.

[0009] In the above technical solution, the packaging welding of the skin, FPC and MEMS sensor in the device adopts the following steps: Step 1: According to the design requirements, set through holes with the same diameter at corresponding positions on the skin and FPC; Step 2: Pass the pressure measuring hole of the MEMS sensor through the through hole of the FPC; Step 3: On the welding surface side of the skin, a solder resist pad is etched outward along the diameter of each through hole, the diameter of the solder resist pad is larger than the diameter of the through hole, and a solder resist pad is etched outward along the diameter on the pressure measuring hole of the MEMS sensor; Step 4: Weld the solder resist pad of the through hole on the skin and the solder resist pad of the pressure measuring hole of the MEMS sensor into one, and the welded solder resist pad forms a sealing ring between the pressure measuring hole of the MEMS sensor and the through hole of the skin; Step 5: On the welding surface of the FPC, weld the pins of the MEMS sensor to the circuit on the FPC; Step 6: Fill the gap between the FPC and the skin to bond the FPC and the skin together; Step 7: Fill the FPC welding surface with sealant to seal the components and the FPC board.

[0010] In the above technical solution, the pressure measuring hole of the MEMS sensor and the through hole of the skin are kept centrally aligned by using the image preset marking point method.

[0011] In the above technical solution, the MEMS sensors arranged in an array on the FPC are filled with sealant into a strip shape, and the lower surfaces of all the strip shapes are in a flat state.

[0012] The device of the present invention is based on the design of a fancy array of surface pulsating pressure wave number domain beamforming, and the design principle is: First, the array is determined according to the number of sensors, and the two-dimensional array coordinate fitness function for the wavenumber domain beamforming method is determined according to the measurement requirements of the two-dimensional pulsating pressure wavenumber-frequency spectrum. . Suppose there is an array with M sensors, of which m Number, n The sensor coordinates are , . Assume that the height above sensor No. 1 is l There is a simple harmonic sound source without attenuation at location , and its position coordinates are , then the pressure signals are: (1) in is the pressure amplitude, are the time delay, angular frequency, wave number vector and relative position vector respectively.

[0013] in: (2) Performing time Fourier transform on equation (1) yields .

[0014] Let the cross-spectral matrix be expressed as , that is dimensional matrix whose elements are cross-spectral functions , T represents the period of the pressure signal, E is the mathematical expectation, for The conjugate function of , the cross-spectral function between the sensors in the array is obtained as: (3).

[0015] According to the requirements of the wavenumber domain beamforming algorithm, the wavenumber steering vector of the array is set for dimensional vector, whose elements correspond to the ,but: (4) in, Representative m The coordinates of the sensors, is the wave number vector in the x direction, is the wave number vector in the z direction, Is an imaginary unit.

[0016] Therefore, the array wave number domain beamforming result at a certain angular frequency can be expressed as: (5) in: (6).

[0017] In order to optimize the distribution of the two-dimensional pulsating pressure sensor array, T in equations (5) and (6) is set to represent the matrix device, and the sensor position is taken as the unknown number to establish the following equation: (7) in, and Depends on the design requirements of the two-dimensional pulsating pressure sensor array, Depending on the diameter of the sensor array, Depends on the maximum frequency recognized by the array.

[0018] In the calculation, since the minimum frequency (maximum wavelength) of the signal that can be measured by the array is determined by the array aperture, and the wave number is inversely proportional to the wavelength, the minimum wave number taken is inversely proportional to the array aperture. From the relationship between wave number and frequency, it can be seen that the higher the frequency, the larger the wave number, so it can be and The values ​​are as follows: (8) in, D is the sensor array diameter, is the maximum frequency measured, is the wave propagation speed.

[0019] Combining formula (7) can be rewritten as: (9) in: (10) Represents the radius and angle coordinates of the array's polar coordinates.

[0020] Using Bessel functions, we can obtain: (11) in, J 0 is the zero-order Bessel function, for The first-order derivative of , Equation (11) is the function form of the optimal sensor layout. When it reaches the minimum value, it corresponds to x n and y nThat is the required sensor position coordinate, which will be solved in subsequent steps.

[0021] Construct array formation optimization objectives.

[0022] The present invention mainly designs and optimizes the acoustic zone measurement of the multi-arm spiral two-dimensional pulsating pressure array. Since the multi-arm spiral is a periodic array, it can ensure that the resolution is at a good level, so the dynamic range is optimized. The optimization is based on the multi-arm spiral array. During the optimization, the minimum inner diameter and maximum outer diameter of the array are specified. The number of microphones on each arm is the same and the arrangement position is the same. Under the condition of the same number of microphones, the optimal array arrangement is found. The optimization design can be expressed as the following formula: (12) in M =54 is the total number of microphones in the array, l= 9 is the number of arms of the array, a =6, the number of microphones on each arm, and are the minimum and maximum inner diameters of the array, respectively. is the minimum limit of particle motion boundary, is the maximum limit of the particle motion boundary.

[0023] The particle swarm is represented by X, and it gradually approaches the optimal formation through an iterative algorithm: (13) Where: N is the number of particles in the particle group, represents the nth particle, and each particle represents a formation of a microphone array.

[0024] The optimal value of each particle in the iteration process is represented by P; the coordinates of all particles are the same as the optimal particle coordinates in the population, and g is used to represent the population optimality: (14) Where: D represents the particle dimension, represents the dth dimension of the nth particle.

[0025] Therefore, the particle velocity and coordinate update formula in the particle swarm is: (15) in, , is the maximum number of iterations set. and is the particle velocity and particle coordinate position after the tth iteration. Through continuous iteration, if the maximum number of iterations is reached and the convergence condition has not been reached, the result of the last iteration is used as the initial value and the iteration is continued until the optimal solution is found.

[0026] Initialize particle swarm Set the population size X = 100, the space dimension N = 6, the maximum number of iterations T = 2000, and the position boundary to r min =0.015m, r out =0.075m, velocity boundary v min =-0.001m / time, v max =0.001m / time, inertia weight , self-learning factor c1 = 2, group learning factor c2 = 2. To generate the initial population, first randomly generate the initial population position, then randomly generate the initial population position, initialize the individual historical best position and individual historical best fitness, and finally initialize the group historical best position and group historical best fitness.

[0027] Calculate the particle fitness and update the individual and group historical best positions. Update the particle position and speed, perform boundary processing, make constraint judgments and repeat.

[0028] The above process is repeated until the maximum number of iterations or the global optimal position meets the minimum limit, and the array formation is obtained. Through the above steps, the desired formation is obtained, that is, Figure 2.

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: The present invention concentrates the measurement units on a flexible FPC in an effective measured space. At the same time, the circuit design needs to take into account both high efficiency and stability. A large number of precision components are reasonably embedded in a narrow and limited space, and the circuit function is realized on the FPC. The signal is transmitted to the adapter board through the FPC and then transmitted to the data acquisition board through a long line. At the same time, the IEPE power supply method is adopted, and the power is directly supplied through the acquisition board to reduce the complexity of the system. At the same time, the IEPE power supply can achieve a one-to-one correspondence with the array element. If an array element in the array is damaged, it will not affect the normal operation of other array elements. The skin and the FPC circuit board in the present invention are sealed by welding, and the electronic components and the FPC are packaged in the form of glue potting, which can protect the IEPE interface circuit, MEMS components, FPC circuit board and other devices to avoid stretching and deformation due to external stress; the curvature of the array can be maintained, and the measured curved surface can be better fitted; after filling, the lower surface of the array can be kept in a flat state, which is beneficial to the conformal effect of the array measurement surface.

[0030] The present invention optimizes the array-oriented two-dimensional wavenumber domain beamforming algorithm, which can take into account the measurement of the turbulent boundary layer acoustic area and the migration ridge area to the greatest extent. The special sealed skin / circuit and special FPC / PCB adapter board are used to achieve high-density integration of array elements while each element works relatively independently, that is, the damage of one element does not affect the work of other elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 This is a diagram of the 76-channel array formation; FIG2 is a schematic diagram of the special sealing skin and circuit board structure; Figure 3 It is the IEPE power supply circuit; Figure 4 is the array-based wavenumber domain beamforming wind tunnel measurement result; Among them: 1 is the skin; 2 is the group welding pad; 3 is the FPC circuit board; 4 is the MEMS sensor; 5 is the skin through hole; 6 is the pressure measuring hole; 7 is the circuit board through hole, and 8 is the sealing layer. DETAILED DESCRIPTION

[0032] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0033] Any feature disclosed in this specification (including any additional claims, abstract and drawings), unless otherwise stated, may be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0034] A simplified diagram of the measuring device of this embodiment is shown in FIG. Figure 2 As shown, it includes a skin 1 and an FPC circuit board 3, and a skin through hole 5 and a circuit board through hole 7 with the same diameter are respectively arranged on the skin 1 and the FPC circuit board 3. The skin 1 and the FPC circuit board 3 are sealed and connected through a solder resist pad 2. After the sealing connection, the skin through hole 5 and the circuit board through hole 7 remain coaxial. A MEMS sensor 4 is arranged on the other side of the FPC circuit board 3, and a pressure measuring hole 6 on the MEMS sensor 4 remains coaxial with the skin through hole 5 and the circuit board through hole 7.

[0035] On one side of the FPC circuit board 3 connected to the MEMS sensor 4, an IEPE power supply circuit is provided. Figure 3 As shown, the circuit can provide power to each array element one by one. If one array element in the array is damaged, it will not affect the normal operation of other array elements.

[0036] like Figure 2As shown, all the electronic components of the FPC circuit board 3 are filled with sealant, so that all the electronic components are sealed with the FPC circuit board 3, and the back of the array is filled in a strip shape, which has three functions. First, it can protect the IEPE interface circuit, MEMS components, FPC circuit board and other devices to avoid stretching and deformation due to external stress; second, the strip filling can maintain the curvature of the array and can better fit the measured curved surface; third, after filling, the lower surface of the array can be kept flush, which is beneficial to the conformal effect of the array measurement surface.

[0037] The array used in this embodiment is designed according to the design method as follows Figure 1 As shown, the array processing is completed by using the skin and circuit board sealing method and the array high-density integration method according to the array.

[0038] First, through holes with a diameter of 0.25 mm are designed according to an array at the corresponding positions of the skin and the FPC circuit board, and solder resist pads with a diameter of 0.5 mm are etched around the through holes of the skin.

[0039] The pressure measuring hole of the MEMS sensor is passed through the through hole of the FPC, and a solder resist pad with a diameter of 0.5 mm is etched around the pressure measuring hole.

[0040] The solder resist pad on the skin is butt-welded with the solder resist pad on the pressure measuring hole. The welding pads after butt-welding form a sealing ring with a diameter of 0.5mm. That is, the welded solder resist pad constitutes a connecting sealing ring between the skin through hole and the circuit board through hole, ensuring that the two 0.25mm through holes are completely sealed to ensure that there is no leakage during the pressure measurement process.

[0041] Next, the components are soldered to the FPC circuit board, and the MEMS sensor device is soldered to the through-hole of the FPC circuit board through a solder ring seal, ensuring that the pressure measuring hole of the MEMS component is coaxial and sealed with the skin through-hole and the circuit board through-hole.

[0042] After the components are welded, glue is filled between the FPC and the skin to bond the FPC and the skin together to ensure that the FPC will not fall off the MEMS sensor due to force during the test.

[0043] Finally, all components on the FPC welding surface and the FPC circuit board are filled with sealant.

[0044] In the actual test, the FPC circuit board is connected to the external host computer through a cable for testing. The angular frequency of the array in this embodiment is 6200 obtained by the array matching wave number domain wave number formation algorithm at a sampling frequency of 51.2kHz, a wind speed of 30.7m / s, and a sampling time of 30s. The test results when Figure 4 shown.

[0045] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A surface pulsation pressure wave number domain beamforming array wind tunnel measurement device, characterized in that: The invention comprises a skin, on which a plurality of through holes are arranged in an array, wherein the array comprises a plurality of uniform annular arrays concentrically from the inside to the outside, and a plurality of spiral arm arrays formed by the annular arrays from the inside to the outside, and a solder resist is coaxially arranged on the outer side of each through hole on the welding surface of the skin, A bendable FPC is arranged under the skin, and the FPC is provided with through holes corresponding to the through holes on the skin one by one. A MEMS sensor is arranged in each through hole on the FPC, and a coaxial solder resist pad is arranged outside the pressure measuring hole after the pressure measuring hole of the MEMS sensor passes through the FPC through hole. The skin and the MEMS sensor are welded together through the solder resist pad, and the MEMS sensor is electrically connected to the FPC. An adapter board connected to the circuit on the FPC, wherein an IEPE power supply circuit is arranged on the adapter board and is independently connected to each MEMS sensor.

2. The surface pulsation pressure wave number domain beamforming array wind tunnel measurement device according to claim 1, characterized in that: The solder resist pad is arranged between the skin and the FPC, the MEMS sensor and the skin are welded together through the solder resist pad, and the circuit pins of the MEMS sensor are welded to the circuit on the FPC.

3. The surface pulsation pressure wave number domain beamforming array wind tunnel measurement device according to claim 2, characterized in that: A packaging layer is arranged on the welding surface of the FPC, and the packaging layer seals the MEMS sensor and the surface of the FPC into one.

4. A surface pulsation pressure wave number domain beamforming array wind tunnel measurement device according to any one of claims 1 to 3, characterized in that: The FPC is bonded to the skin as a whole.

5. The surface pulsation pressure wave number domain beamforming array wind tunnel measurement device according to claim 1, characterized in that: The pressure measuring hole of the MEMS sensor is aligned with the center of the through hole of the corresponding skin.

6. A method for installing a surface pulsation pressure wave number domain beamforming array wind tunnel measurement device, characterized in that The installation of the skin, FPC and MEMS sensor components in the device adopts the following steps: Step 1: According to the design requirements, set through holes with the same diameter at corresponding positions on the skin and FPC; Step 2: Pass the pressure measuring hole of the MEMS sensor through the through hole of the FPC; Step 3: On the welding surface side of the skin, a solder resist pad is etched outward along the diameter of each through hole, the diameter of the solder resist pad is larger than the diameter of the through hole, and a solder resist pad is etched outward along the diameter on the pressure measuring hole of the MEMS sensor; Step 4: Weld the solder resist pad of the through hole on the skin and the solder resist pad of the pressure measuring hole of the MEMS sensor into one, and the welded solder resist pad forms a sealing ring between the pressure measuring hole of the MEMS sensor and the through hole of the skin; Step 5: On the welding surface of the FPC, weld the pins of the MEMS sensor to the circuit on the FPC; Step 6: Fill the gap between the FPC and the skin to bond the FPC and the skin together; Step 7: Fill the FPC welding surface with sealant to seal the components and the FPC board.

7. The method for installing a surface pulsation pressure wave number domain beamforming array wind tunnel measurement device according to claim 6, characterized in that: By using the image preset marking point method, the pressure measuring hole of the MEMS sensor is kept centrally aligned with the through hole of the skin.

8. The method for installing a surface pulsation pressure wave number domain beamforming array wind tunnel measurement device according to claim 6, characterized in that: The MEMS sensors arranged in an array on the FPC are filled with sealant into a strip shape, and the lower surfaces of all the strip shapes are in a flat state.

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