Multi-point pressure data synchronous parallel acquisition system and application method

Abstract

The application discloses a kind of multi-point pressure data synchronous parallel acquisition system and application method, it is related to wind tunnel test field, comprising: multiple pressure points to be measured;Multiple acquisition units are communicated with each point to be measured by pressure transmission pipeline;Multiple acquisition modules are integrated by grouping each acquisition unit;Multiple acquisition modules form acquisition terminal;Synchronous control module controls the synchronous acquisition of multiple acquisition terminals;Central processing unit;Wherein, each acquisition unit is respectively provided with independent, same type AD digital instrument, and each AD digital instrument is phase-locked by corresponding phase-locked loop;Timestamp counter is integrated in the processor of AD digital instrument;Each acquisition terminal is respectively provided with corresponding synchronous trigger.The application provides a kind of multi-point pressure data synchronous parallel acquisition system and application method, can carry out synchronous pressure acquisition to hundreds of points, reduces acquisition delay error, and accuracy is higher.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wind tunnel test. More particularly, the present application relates to a multi-point pressure data synchronous parallel acquisition system and application method for high-precision synchronous parallel acquisition of multiple point pressure data measured by electronic pressure scanning valves in wind tunnel test. BACKGROUND

[0002] There are many types of data to be collected in wind tunnel test, and pressure is one of the most important parameters. The pressure mainly refers to the total pressure of the stable section of the wind tunnel, the static pressure of the test section, the injection pressure of the injection section, the total pressure field after the wave, the static pressure field of the flow field, and the model surface pressure. Through the measurement of these pressures, important wind tunnel test data such as wind speed, aerodynamic force coefficient, and model surface flow characteristics can be calculated. Among them, the measurement of the total pressure field after the wave, the static pressure field of the flow field, and the model surface pressure belongs to large-scale pressure measurement, which requires simultaneous measurement of tens to hundreds of pressure points.

[0003] If one pressure sensor is configured for one pressure measurement point, then for large-scale pressure measurement in wind tunnel test, thousands of pressure sensors need to be connected simultaneously for pressure acquisition, which will cause great system burden and resource waste. Since the introduction of electronic pressure measurement system from the United States in the 1990s, electronic pressure measurement has been mainly used for large-scale pressure measurement in wind tunnel test. A pressure measurement system is configured with multiple acquisition modules, each acquisition module has tens to dozens of acquisition units, and nearly a thousand pressure measurement points can be measured simultaneously. Pressure measurement system has been widely used in wind tunnel test due to its small size, high precision, and large number of measurement points.

[0004] However, in the specific use of electronic pressure measurement, there are the following three defects:

[0005] First, the existing electronic pressure scanning valve, all pressure acquisition units on one module share one AD digital instrument, and there is only serial mode for pressure data acquisition, which cannot realize parallel acquisition of multiple pressure data.

[0006] Second, the existing electronic pressure scanning valve measures pressure data in a polling mode, that is, all pressure acquisition units on the acquisition module record pressure data in sequence, and there is a delay Δt in time between data of adjacent two acquisition units. The more the pressure acquisition units of the module, the greater the delay in recording pressure time between the first acquisition unit and the last acquisition unit, and the delay is (n-1)*Δt, where n is the number of acquisition units on the module. At the same time, in order to reduce the random error of pressure data, several pressure values of the same acquisition unit are averaged to obtain the final acquired pressure value, and at this time, the delay in recording pressure time between the first acquisition unit and the last acquisition unit is (nk-1)*Δt, as shown in Figure 1 In addition, when large-scale pressure measurement is performed, the sampling rate of electronic pressure measurement is set to be small to ensure real-time data reading and processing, and is generally about 100 Hz. At this time, there is a second-level error in recording time of data between pressure acquisition units, because the measured pressure in the wind tunnel test is a fluctuating value, and the delay in acquisition time causes the final acquired pressure data to be not the pressure value at the same time, resulting in a large error.

[0007] Third, when large-scale pressure measurement is performed in the wind tunnel test, a plurality of pressure measurement modules are required, and the acquisition trigger signals between the modules are transmitted in a network transmission mode or a cable transmission mode. As shown in Figure 2 Because of the delay in transmission time and the different phases of clock signals between different acquisition modules, there is a random acquisition time delay between different modules, which brings error to the final data. SUMMARY

[0008] An object of the present application is to solve at least the above problems and / or defects, and to provide at least the advantages to be described later.

[0009] To achieve these objects and other advantages of the present application, a multi-point pressure data synchronous parallel acquisition system is provided, which comprises: a plurality of pressure measurement points for measuring steady load of a flow field and an aircraft model;

[0010] a plurality of acquisition units in communication with the measurement points through pressure transmission pipelines;

[0011] a plurality of acquisition modules in which the acquisition units are grouped and integrated;

[0012] an acquisition terminal composed of a plurality of acquisition modules with a core controller and a bus synchronous clock;

[0013] a central processing unit for analyzing, storing and processing pressure data acquired by each acquisition terminal through a hub;

[0014] Each acquisition unit is equipped with an independent, identical AD digital instrument, and each AD digital instrument is phase-locked through a corresponding phase-locked loop;

[0015] The processor of the AD digital instrument integrates a timestamp counter;

[0016] Each data acquisition terminal is equipped with a corresponding synchronization trigger.

[0017] A method for using a multi-point pressure data synchronous parallel acquisition system in wind tunnel testing includes:

[0018] S10. Periodically output standard pressure values ​​to each pressure acquisition unit through the pressure controller to complete the system operating coefficient calibration;

[0019] Before each pressure data acquisition begins, a zero-point calibration is performed on the current pressure environment.

[0020] S11, the synchronization control module provides a phase-locked common clock to each acquisition terminal to ensure that the AD digital instrument of each acquisition unit is in the same ready-to-trigger state;

[0021] S12, the central processing unit sends a trigger command to each acquisition terminal through a synchronous trigger. After receiving the trigger command, each acquisition terminal sets an acquisition start point for the AD digital instrument of each acquisition unit in each acquisition module and starts acquiring pressure signals. During the acquisition process, the clock frequency of each AD digital instrument is phase-locked through a phase-locked loop to ensure that the phase of each acquisition unit does not shift with the acquisition time. The pressure signal acquired by each AD digital instrument is recorded in the timestamp counter as the number of sampling cycles of each AD digital instrument before the current synchronous trigger event occurs, and the error of the trigger time start point between different acquisition units is identified and corrected.

[0022] S13, each acquisition terminal transmits the acquired pressure signal back to the central processing unit through the hub to achieve synchronous signal acquisition.

[0023] Preferably, in S12, the identification and correction of the trigger time start point error between different acquisition units is configured to include:

[0024] The timestamp counter in each acquisition unit counts the sampling clock in its respective unit;

[0025] When the synchronous acquisition trigger pulse arrives, record the number of sampling cycles that have occurred in each acquisition unit;

[0026] Compare the difference in the number of sampling cycles recorded by each acquisition unit when the trigger pulse arrives;

[0027] The starting point for reading the data stream is determined based on the difference in the number of cycles recorded by each acquisition unit.

[0028] When the acquisition unit I is 2 sample pulse period counts less than the acquisition unit J, the acquisition unit I data stream is normally read, and the acquisition unit J reads the data two sample periods before the trigger time as the starting point of the data stream.

[0029] Preferably, in S10, the calibration step of the system operating coefficient is configured to include:

[0030] S1110, within the measurement range of the pressure measurement module, 11 test pressure points are selected according to the following formula:

[0031] (1)

[0032] , i = 2, 3, …, 10 (2)

[0033] (3)

[0034] (4)

[0035] Wherein, E L represents the lower limit of the pressure measurement range, E H represents the upper limit of the pressure measurement range, E r represents the range of pressure measurement, E i represents the calibration pressure value loaded at the i-th point (i = 1, 2, …, 11);

[0036] S1111, connect the measurement unit to be corrected with the output interface of the standard pressure controller by the pressure transmission pipeline;

[0037] S1112, use the standard pressure controller to output the selected 11 pressure test signals, start the data recording of the data acquisition system, record 100 data results at each pressure test point, and calculate the average value;

[0038] S1113, use the least square method to fit the slope and intercept of each pressure measurement point, and complete the calibration.

[0039] Preferably, in S10, the zero point calibration operation step is:

[0040] S1120, expose the measurement port and the pressure reference port of each measurement unit in the pressure measurement module to the same air pressure environment;

[0041] S1121, start data recording of the data acquisition system, repeat recording of 100 data results, and calculate the average value thereof;

[0042] S1122, calculate the differential pressure between the measurement port and the pressure reference port of each measurement unit;

[0043] S1123, when the pressure value is formally acquired, subtract the differential pressure measured in the zero calibration from the acquired pressure value to obtain the actually measured pressure value.

[0044] Preferably, the method further comprises eliminating the error of the total pressure and the steady-state pressure conduction delay in the measurement of the wind tunnel.

[0045] Preferably, the elimination method is configured to comprise:

[0046] S20, when the total pressure and the steady-state pressure are synchronously measured by each corresponding acquisition unit in each wind tunnel test, determine the time scale of each group of data;

[0047] S21, based on the time scale t1 corresponding to the total pressure peak value and the time scale t2 corresponding to the steady-state pressure peak value, obtain the delay Δt = t1-t2 between the total pressure fluctuation and the steady-state pressure fluctuation in the flow field;

[0048] S22, when the data is processed for the i-th time, select the steady-state pressure value Pk(t) of the k-th measuring point at the time t + Δt as the total pressure value P0(t) of the total pressure P0 at the time t, so as to eliminate the error of the total pressure and the steady-state pressure conduction delay. i k (t i +Δt), as the total pressure value P0(t i ) of the total pressure P0 at the time t i , so as to eliminate the error of the total pressure and the steady-state pressure conduction delay.

[0049] The present application at least has the following beneficial effects: first, the system of the present application can ensure that the clock frequencies of the AD digitizers of the acquisition units are completely consistent and the phases are not offset with time by using independent and same type AD digitizers in each acquisition unit and by locking the phases through the phase-locked loop, so as to ensure that the sampling clock of the acquisition units in one module is consistent;

[0050] Second, the present application can ensure that the AD digitizers of each acquisition unit in each acquisition module are in the same triggered state by providing a common clock after phase locking.

[0051] Third, the present application introduces a time stamp counter in the AD digitizer of each acquisition unit, which records the number of sampling periods of the AD digitizer in each acquisition unit before the synchronous triggering event occurs, so as to identify and correct the triggering time error between different acquisition units, and solve the triggering error between the acquisition units. ​

[0052] Fourthly, the application further ensures the starting point of data recording of each acquisition module and the consistency of acquisition state and acquisition trigger time between acquisition modules in the same terminal by the core controller and bus synchronous clock in the terminal.

[0053] Fifthly, the application further provides synchronous clock and synchronous trigger between terminals by external synchronous controller to ensure the consistency of acquisition state and acquisition trigger time between terminals.

[0054] Other advantages, objects, and features of the application will be better understood from the following description taken in conjunction with the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 The figure shows the error in data recording time of acquisition units under different time sequences when the polling system is used to collect pressure data in the prior art;

[0056] Figure 2 The figure shows the trigger error caused by the delay of transmission time and the different phases of clock signals between different acquisition modules in the prior art;

[0057] Figure 3 System composition block diagram of the application;

[0058] Figure 4 Composition block diagram of one of the subsystems of the application;

[0059] Figure 5 Schematic diagram of the system of the application in synchronous acquisition;

[0060] Among them, the acquisition terminal-1, the acquisition unit-11, the acquisition module-10, the AD digital instrument-12, the phase-locked loop-13, the pressure sensor-14, the signal conditioning circuit-15, the central processing unit-2, the synchronous control module-3, and the pressure controller-4. DETAILED DESCRIPTION

[0061] The application will be further described in detail below with reference to the drawings, so that those skilled in the art can implement it according to the description.

[0062] It should be understood that the terms such as "have", "contain", and "include" used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0063] As Figures 3-4 A multi-point pressure data synchronous and parallel acquisition system in wind tunnel test, comprising:

[0064] A plurality of pressure test points for measuring the flow field and the steady load of the aircraft model;

[0065] A plurality of acquisition units 11 in communication with each test point through a pressure transmission pipeline;

[0066] A plurality of acquisition modules 10 for grouping and integrating each acquisition unit;

[0067] An acquisition terminal 1 composed of a plurality of acquisition modules with a core controller and a bus synchronous clock;

[0068] A central processing unit 2 for analyzing, storing and processing the pressure data collected by each acquisition terminal through the hub;

[0069] Each acquisition unit is provided with an independent and identical AD digitizer 12, and each AD digitizer is phase-locked through a corresponding phase-locked loop 13;

[0070] The processor of the AD digitizer is integrated with a timestamp counter;

[0071] Each acquisition terminal is provided with a corresponding synchronous trigger, and each acquisition terminal is connected with the central processing unit through a synchronous control module 3, which provides the synchronous clock and the synchronous trigger pulse for each acquisition terminal. In the specific implementation of the present scheme, each acquisition module is configured to include:

[0072] A plurality of pressure sensors 14 matched with the test points on the air path connection assembly;

[0073] A digital A / D instrument and a signal conditioning circuit 15 in communication connection with each pressure sensor to build a corresponding measurement channel;

[0074] A pressure measurement assembly in communication connection with each first signal conditioning circuit to realize the synchronous acquisition of each pressure sensor, which adopts a modular design to make the interface extensible without affecting the overall technical indicators of the system;

[0075] Each acquisition terminal is configured to include:

[0076] A pressure measurement machine case (not shown) for integrating each pressure measurement assembly, which is provided with a first controller with an operating system, each pressure measurement assembly is inserted into the pressure measurement machine case, completing the modular integration of pressure measurement, the machine case is a 4U standard rack machine case, with a core controller slot, up to 8 acquisition modules can be inserted, the first machine case card uses a quick insertion structure, the panel has locking screws, which can be tightened to reinforce the card installation, the core controller is the core component of the steady-state pressure measurement system, equivalent to the CPU and mainboard of the acquisition device, which can complete data acquisition management, acquisition instruction sending, data transmission and other functions. The operating system of the core controller is an RT real-time operating system. When interacting with external data, the real-time operating system can process it at a fast enough speed, and the result of its processing can control the production process or make a quick response to the processing system within the specified time, schedule all available resources to complete real-time tasks, and control all real-time tasks to run in coordination. The operating system has the advantages of timely response and high reliability compared to a time-sharing operating system. For a data acquisition and processing server, the synchronous acquisition component is like a black box, the preset program in the core controller automatically calls and runs the synchronous acquisition function, receives the acquisition instruction sent by the server through the driver program, and sends the acquisition data to the data acquisition and processing server;

[0077] A pressure controller 4 connected to each pressure measurement assembly to provide a standard pressure.

[0078] The pressure controller mainly outputs a standard pressure to provide a standard pressure source to facilitate the calibration and troubleshooting of the work coefficient of the pressure measurement unit. In this scheme, the parameter indicators of each pressure measurement assembly need to meet the requirements of Table 1 to have the ability of phase synchronous acquisition between units, between pressure measurement modules, and between terminals.

[0079] Table 1

[0080]

[0081] In actual application, each pressure measurement assembly in the system of the present application is configured to include:

[0082] A first FPGA for processing and outputting signals input to the signal conditioning circuit;

[0083] A first phase-locked loop (PLL), a first clock management module, and a CPU in communication connection with the first FPGA;

[0084] Among them, the external communication interface, the synchronous clock signal, and the synchronous trigger signal are all in communication connection with the first clock management module and the CPU through the control bus;

[0085] The central processing unit (also referred to as a control unit) in the application is configured to include:

[0086] A rack with a front panel having a signal interface;

[0087] A second FPGA arranged inside the rack;

[0088] A second phase-locked loop (PLL), a second clock management module, and a synchronization signal generator in communication with the second FPGA;

[0089] The control unit is in communication with each pressure measurement component through a shunt, the overall structure of the control unit is designed in a 1U rack type structure, the front panel is configured with a signal interface to access input and output signals, the synchronization module communicates with an upper computer through a USB port, and the hardware devices in the system all adopt an embedded architecture based on FPGA, the hardware architecture based on FPGA+AD has high real-time performance in line with test conditions, can not only realize signal acquisition and storage, but also has strong synchronization, low power consumption, and high reliability; the control unit as an external trigger source is in synchronous connection with multiple acquisition terminals through a shunt to realize the layout of multiple device synchronous triggering.

[0090] Each measurement module of the scheme adopts a modular design, the functions of each module are independent and uncoupled. The modular design is easy to expand the system capacity and improve the maintenance efficiency.

[0091] The FGPA realizes data acquisition, data processing, data sending and other operations inside the FPGA through a standard PCIe interface. According to the functions, it is divided into an interface unit, a processing unit, an output unit and the like, and adopts a data flow driving mode between units. After the data processing of the unit is completed, the data is packaged and sent to the next stage to realize data exchange inside the architecture.

[0092] FPGA design elements include interface design, clock design, reset design, function design, etc. The criterion for interface design is: do not add too much logic, avoid adding logic congestion to affect the interface timing; Clock includes logic clock, interface clock, memory clock, etc. The logic clock depends on the critical path of the logic, and improves the performance of the product. When FPGA realizes the timing of the synchronization signal, the fixed and accurate interface clock is used to realize the synchronization of the interface. The memory clock realizes the synchronization of the data, and the design should avoid the data loss or instability caused by the refresh frequency; The internal reset of FPGA includes hard reset, logic reset, soft reset, etc. The hard reset is introduced by the external pin reset, which is input during power-on, so that the whole FPGA logic configuration is completed and reaches a stable state. The logic reset is generated by the internal logic of FPGA, which is used to set the preparation state of signals such as synchronization control. The soft reset is used in the debugging stage, and the soft reset is inserted at the test point, fault positioning point, etc. It can quickly locate and divide the problem, and speed up the debugging speed. The function design includes signal acquisition, signal conditioning, synchronization control, data transmission and other functions through FPGA. The principle of function design is stable and efficient, and the required circuit implementation function and the constraint condition of implementing this circuit are considered, such as speed, power consumption and circuit type.

[0093] An application method of a multi-point pressure data synchronous parallel acquisition system in a wind tunnel test, comprising:

[0094] S10, periodically outputting a standard pressure value to each pressure acquisition unit through a pressure controller to complete system working coefficient calibration;

[0095] Before each pressure starts to collect, zero point calibration is performed on the current pressure environment;

[0096] S11, the synchronization control module provides a phase-locked common clock to each acquisition terminal to ensure that the AD digital instruments of each acquisition unit are in the same trigger state;

[0097] S12, the central processing unit sends a trigger instruction to each acquisition terminal through a synchronization trigger, each acquisition terminal sets an acquisition starting point for the AD digital instrument of each acquisition unit, starts pressure signal acquisition, and the clock frequency of each AD digital instrument is locked through a phase-locked loop during the acquisition process, so as to ensure that the phase of each acquisition unit does not shift with the acquisition time, and the pressure signals collected by each AD digital instrument are counted by a time stamp counter to record the sampling period number of each AD digital instrument before the current synchronization trigger event occurs, so as to identify and correct the trigger time starting point error between different acquisition units;

[0098] S13, each acquisition terminal returns the collected pressure signals to the central processing unit through the hub to realize synchronous signal acquisition.

[0099] Figure 5The synchronization between different acquisition units is explained, and Mach 8 is taken as an example, the target value of total pressure is 5 MPa, and the control accuracy requirement of total pressure is within 0.5%, which means that in the same wind tunnel test, the total pressure value may change by 25000 Pa at most within a few seconds. After eliminating the delay error, the acquisition values at different times can be attributed to the same place, realizing the synchronous acquisition of multiple points, which can eliminate the maximum 25000 Pa fluctuation error of the total pressure value participating in the calculation in the later stage, and improve the data accuracy. Figure 1

[0100] Further, the system working coefficient and zero point calibration are explained:

[0101] 1. Pressure measurement unit working coefficient calibration

[0102] a. In the measurement range of the pressure measurement module, 11 test pressure points are selected according to formulas 1-4;

[0103] (1)

[0104] , i = 2, 3, …, 10 (2)

[0105] (3)

[0106] (4)

[0107] Wherein, E L represents the lower limit of the pressure measurement range, E H represents the upper limit of the pressure measurement range, E r represents the range of pressure measurement, E i represents the calibration pressure value loaded at the i-th point (i = 1, 2, …, 11);

[0108] b. Connect the measurement unit to be calibrated with the output interface of the standard pressure controller by a pressure transmission pipeline;

[0109] c. Use the standard pressure controller to output the selected 11 pressure test points, start the data recording of the data acquisition system, record 100 data results at each pressure test point, and calculate the average value;

[0110] d. Use the least square method to fit the working slope and intercept of each pressure measurement unit according to the 11 groups of standard pressure values and the pressure values measured by the pressure measurement unit obtained in step C.

[0111] 2. Zero point calibration

[0112] ​Because the pressure measurement system is a differential pressure working mode, the pressure measurement unit needs to be calibrated to zero before each formal pressure measurement. The steps are as follows:

[0113] a. Expose the measurement port and pressure reference port of each measurement unit in the pressure measurement module (each pressure module has a common reference pressure port) to the same air pressure environment;

[0114] b. Start the data record of the data acquisition system, and repeat the data record 100 times;

[0115] c. Calculate the average value of the 100 data results in b as the pressure difference of the measurement port and the pressure reference port of each measurement unit;

[0116] d. When the pressure value is formally collected, subtract the pressure difference measured during zero calibration from the collected pressure value, and the actual measured pressure value is obtained.

[0117] Further comprising eliminating the total pressure and flow field steady-state pressure conduction delay error in the measurement of the wind tunnel.

[0118] The elimination method is configured to include:

[0119] S20, when synchronously measuring the total pressure and the flow field static pressure by each corresponding acquisition module at each wind tunnel test, determining the time mark of each group of data;

[0120] S21, based on the total pressure peak value corresponding time mark t1 and the flow field static pressure peak value corresponding time mark t2, obtaining the delay Δt=t1-t2 between the total pressure fluctuation and the steady-state pressure fluctuation in the flow field;

[0121] S22, when performing data processing for the i-th time, selecting the steady-state pressure value Pk(t+Δt) of the k-th measuring point at the t+Δt moment as the total pressure value P0(t) of the total pressure P0 at the t moment, so as to eliminate the conduction delay error between the total pressure and the flow field steady-state pressure. i k i i i

[0122] Taking Mach 8 as an example, the target value of the total pressure is 5MPa, and the control accuracy requirement of the total pressure is within 0.5%, which means that in the same wind tunnel test, the total pressure value may change by 25000Pa in a few seconds. After eliminating the delay error, the collection values at different moments can be attributed to the same place, realizing the synchronous collection of multiple points, and the total pressure value participating in the calculation later will eliminate the error of the maximum fluctuation of 25000Pa. Figure 1

[0123] ​​​​​​The above-described arrangements are merely illustrative of the application and are not intended to limit the present application. The application can be practiced with variations within the spirit and scope of the present application, as will be apparent to those skilled in the art.

[0124] The number of devices and processes illustrated herein are used to simplify the explanation of the present application. Applications, modifications, and variations of the present application will be apparent to those skilled in the art.

[0125] While the embodiments of the application have been disclosed as above, it is not limited to the application listed in the specification and the embodiments. It can be applied to various fields suitable for the present application. Further modifications can be easily made by those skilled in the art. Therefore, the present application is not limited to the specific details and the figures shown and described herein. It is intended to cover the general concepts of the claims and their equivalents.

Claims

1. A multipoint pressure data synchronous parallel acquisition system, characterized in that, The application relates to a pressure synchronous acquisition system. The system comprises: a plurality of pressure test points for measuring the flow field and the steady load of an aircraft model; a plurality of acquisition units in communication with the test points through pressure transmission pipelines; a plurality of acquisition modules for grouping and integrating the acquisition units; a plurality of acquisition terminals formed by the acquisition modules and a bus synchronous clock; a synchronous control module for synchronously controlling the acquisition terminals; a central processing unit for analyzing, storing and processing the pressure data collected by the acquisition terminals through a hub; wherein each acquisition unit is provided with an independent and same type AD digitizer, and each AD digitizer is phase-locked through a corresponding phase-locked loop; a time stamp counter is integrated in the processor of the AD digitizer; each acquisition terminal is connected with the central processing unit through the synchronous control module; 2. An application method of the multi-point pressure data synchronous parallel acquisition system as described in claim 1, characterized in that, each acquisition terminal is provided with a corresponding synchronous trigger. The application also relates to a pressure synchronous acquisition method. S10, periodically outputting a standard pressure value to each pressure acquisition unit through a pressure controller to complete system working coefficient calibration; zero point calibration is performed on the current pressure environment before each pressure starts to be collected; S11, the synchronous control module provides a phase-locked common clock to each acquisition terminal to ensure that the AD digitizers of the acquisition units are in the same trigger state; S12, the central processing unit sends a trigger instruction to each acquisition terminal through a synchronous trigger, each acquisition terminal sets an acquisition starting point for the AD digitizer of each acquisition unit in each acquisition module after receiving the trigger instruction, starts pressure signal acquisition, and the clock frequency of each AD digitizer is phase-locked through a phase-locked loop during the acquisition process, so that the phase of each acquisition unit does not deviate with the acquisition time, the pressure signals collected by each AD digitizer are recorded by the time stamp counter, and the trigger time starting point error between different acquisition units is identified and corrected; 3. The method of claim 2, wherein the method further comprises: S13, each acquisition terminal returns the collected pressure signals to the central processing unit through a hub to realize synchronous acquisition of the signals. In S12, identifying and correcting the trigger time starting point error between different acquisition units is configured to include: the time stamp counter in each acquisition unit counts the sampling clock in the unit; when a synchronous acquisition trigger pulse arrives, the number of sampling periods that have occurred in each acquisition unit is recorded; the difference between the number of sampling periods that have occurred in each acquisition unit when the trigger pulse arrives is compared; the starting point of the data stream is determined according to the difference between the number of sampling periods that have occurred in each acquisition unit; 4. The method of claim 3, wherein the method further comprises: when the sampling pulse period count of acquisition unit I is 2 less than that of acquisition unit J, the data stream of acquisition unit I is normally read, and the data of two sampling periods before the trigger time of acquisition unit J is read as the starting point of the data stream. In S10, the calibration step of the system working coefficient is configured to include: （1） ，i=2,3,...，10 （2） （3） （4） wherein, E L represents the lower limit of the pressure measurement range, E H represents the upper limit of the pressure measurement range, E r represents the range of the pressure measurement, E i represents the calibration pressure value loaded at the i-th point (i = 1, 2, …, 11); S1110, within the measurement range of the pressure measurement module, 11 test pressure points are selected according to the following formula; S1111, the measurement unit to be calibrated is connected with the output interface of the standard pressure controller through a pressure transmission pipeline; S1112, using the standard pressure controller output selected 11 pressure test signal, start data acquisition system data record, record 100 data results at each pressure test point, and calculate the average value; S1113, using the least square method to fit the slope and intercept of each pressure measurement point, complete the calibration.

5. The method of claim 3, wherein the method further comprises: determining the number of the pressure data acquisition units; and determining the number of the pressure data acquisition units based on the number of the pressure data acquisition units. In S10, the zero point calibration operation step is: S1120, expose the measurement port and pressure reference port of each measurement unit in the pressure measurement module to the same air pressure environment; S1121, start the data recording of the data acquisition system, record 100 data results repeatedly, and calculate the average value; S1122, calculate the pressure difference of the measurement port and the pressure reference port of each measurement unit; S1123, when collecting the pressure value, subtract the pressure difference measured by the zero calibration from the collected pressure value to obtain the actual measured pressure value.

6. The method of claim 2, wherein the method further comprises: determining the number of the pressure data acquisition units; and determining the number of the pressure data acquisition units to be synchronized. It also includes eliminating the total pressure and flow field steady pressure conduction delay error in the pressure measurement of the wind tunnel.

7. The method of claim 6, wherein the method further comprises: determining the number of the pressure data acquisition units; and determining the number of the pressure data acquisition units based on the number of the pressure data acquisition units. The elimination method is configured to include: S20, when synchronously measuring the total pressure and the flow field static pressure by each corresponding acquisition unit at each wind tunnel test, determine the time mark of each group of data; S21, based on the total pressure peak value corresponding time mark t1 and the flow field static pressure peak value corresponding time mark t2, to obtain the delay Δt=t1-t2 of the total pressure fluctuation and the steady state pressure fluctuation in the flow field. S22, at the i-th time of data processing, selecting t i +Δt corresponding to the steady-state pressure value P of the kth measuring point k (t i +Δt), as the total pressure P0(t i ) at t i +Δt corresponding to the total pressure value P0(t +Δt), to eliminate the error of the conduction delay between the total pressure and the flow field steady-state pressure.

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