CN115508040B - Synchronous parallel acquisition system for data of speed field and temperature field and application method - Google Patents
Synchronous parallel acquisition system for data of speed field and temperature field and application method Download PDFInfo
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Abstract
The invention discloses a synchronous parallel acquisition system for speed field and temperature field data and an application method, which relate to the field of wind tunnel tests and comprise a total pressure measurement subsystem and a stable section total pressure and temperature field dynamic data acquisition subsystem; each subsystem is respectively provided with at least one acquisition terminal, each acquisition unit in each acquisition terminal uses an independent AD digital instrument with the same type, phase locking is carried out through a phase-locked loop, and a processor of the AD digital instrument is integrated with a timestamp counter; each subsystem provides a phase-locked synchronous clock for each acquisition terminal through a matched external synchronous control module; and each acquisition terminal of each system is communicated with the central processing unit through the synchronous trigger. The invention provides a synchronous parallel acquisition system and an application method for data of a velocity field and a temperature field, which can realize synchronous parallel acquisition of dynamic data of a hypersonic wind tunnel test velocity field and the temperature field in different acquisition systems and effectively ensure the acquisition accuracy and time domain correlation of the data.
Description
Technical Field
The invention relates to the field of wind tunnel tests. More specifically, the invention relates to a system for synchronously and parallelly acquiring data of a speed field and temperature field in a wind tunnel test and an application method thereof.
Background
In the wind tunnel test, the quality of the flow field directly determines the quality of the wind tunnel test data. There are many indexes for measuring the flow field quality, and the velocity field distribution index is the key of them. For the hypersonic wind tunnel, besides velocity field distribution, temperature field distribution also has important influence on whether test data are accurate and reliable. Therefore, the regular speed field and temperature field calibration and measurement of the hypersonic wind tunnel is important work for ensuring the quality of the flow field and further ensuring the test data quality of the wind tunnel.
When the velocity field of the hypersonic wind tunnel is calibrated, the disturbance in the hypersonic wind field is propagated backwards in the Mach cone, so that the Mach number on the central line of the core flow of the test section is not enough to represent the Mach number distribution of the test section, and the spatial Mach number distribution calibration must be carried out, generally, a plurality of sections of the test section are selected to calibrate the section Mach number distribution.
As shown in figure 1, a total pressure exhaust pipe is formed by a cross total pressure detection pipe and a wedge-shaped pipe rack for fixing the detection pipe. And a pressure guiding hose is connected behind the total pressure detection pipe, and the hose penetrates through an inner hole of the calandria support rod and then is connected with the electronic pressure scanning valve. The outer surface of the calandria supporting rod is made into a screw rod shape, the calandria supporting rod is installed on the rigid support, the worm wheel is meshed with the screw rod, the worm wheel is driven by a motor installed outside the wind tunnel body to drive the screw rod to move back and forth, so that the total pressure calandria can move back and forth to measure the post-wave total pressure distribution of each interface of the flow field, and the Mach number distribution of the flow field is calculated by utilizing the total pressure of the stable section and the post-wave total pressure.
The temperature field calibration mode is similar to the speed field calibration mode, and the difference is that: the total pressure bent frame is changed into a total temperature bent frame; a temperature sensor thermocouple is arranged at the temperature measuring hole on the total temperature bent frame to realize temperature measurement; during speed field calibration, electronic pressure scanning valve collection is used for wave-rear total pressure data to directly obtain pressure data, and during temperature field measurement, a voltage signal data collection system is used for collecting hotspot even data, and collected voltage signals are converted into temperature values.
The current calibration of the hypersonic velocity field and the temperature field has the following problems:
1. as shown in fig. 2, during the velocity field calibration, the electronic pressure scanning valve system used for the post-wave total pressure measurement is configured with a plurality of acquisition terminals, each acquisition terminal is provided with tens to tens of acquisition units, and the data acquisition mode is a polling mode, that is, all the pressure acquisition units of the acquisition terminal record pressure data one by one according to the sequence, the data between two adjacent acquisition units has a time delay Δ t, the more the pressure acquisition units of the terminal are, the larger the time delay of recording the pressure between the first acquisition unit and the last acquisition unit is, the delay is (n-1) × Δ t, and n is the number of the acquisition units on the terminal. Meanwhile, in order to reduce the random variation error of the pressure data, a plurality of pressure values of the same acquisition unit are averaged to be used as the finally acquired pressure value, and the delay of the pressure recording time between the first acquisition unit and the last acquisition unit is (nk-1) × Δ t. In addition, in order to ensure the real-time performance of data reading and processing, the sampling rate of the electronic pressure scanning valve is set to be small, and is generally about 100 Hz. At the moment, the data recording time between the pressure acquisition units has an error of a second level, and because the measured pressure in the wind tunnel test is a fluctuation value, the finally acquired pressure data is not a pressure value at the same moment, and a larger error is caused by the delay of the acquisition time.
2. As shown in fig. 3, the collection trigger signals of the multiple pressure scanning valve terminals are transmitted by a network or a cable. Because of the delay of the transmission time and the different phases of the clock signals between different acquisition terminals, a random acquisition time delay exists between different terminals, and errors are brought to final data.
3. The total pressure of the stable section fluctuates due to factors such as the change of the air source pressure, the action delay of the pressure regulating valve and the like, and the total pressure P is obtained at hypersonic speed 0 The total pressure is considered to be stable when the control fluctuates within the range of 0.3% to 0.5%. The total pressure after the wave in the test section fluctuates along with the fluctuation of the total pressure, and the fluctuation frequencies of the total pressure and the total pressure are consistent. However, because the position of the total pressure measuring point of the stable section is a certain distance from the position of the total pressure measuring point after the test section wave, the distance is different from several meters to tens of meters according to the size of the wind tunnel, so that a delay delta t exists between the total pressure fluctuation of the stable section and the total pressure fluctuation after the test section wave. In the current data processing method, there is no way to eliminate the effect of the delay, and the effect can only be ignored.
4. During speed field calibration, an electronic pressure scanning valve is used for measuring total pressure after a wave, and during temperature field calibration, a conventional data acquisition system is used for measuring a temperature field, and the conventional data acquisition system are mutually independent two systems, so that strict synchronization on data cannot be maintained, and time domain correlation is lacked.
Disclosure of Invention
An object of the present invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.
In order to achieve the objects and other advantages of the present invention, a synchronous parallel data acquisition system for speed field and temperature field is provided, which is characterized in that the system comprises a speed field calibration time-wave total pressure measurement subsystem, a stable section total pressure and temperature field dynamic data acquisition subsystem which are independent of each other;
in the test section, a measurement bent frame for measuring total pressure and total temperature is integrally arranged;
the system comprises a plurality of subsystems, a phase-locked loop and a clock signal acquisition unit, wherein each subsystem is respectively provided with at least one acquisition terminal, each acquisition unit in each acquisition terminal uses an independent AD digital instrument with the same type and is phase-locked through a phase-locked loop, and a processor of the AD digital instrument is integrated with a timestamp counter;
each subsystem provides a phase-locked synchronous clock for each acquisition terminal through a matched external synchronous control module;
and each acquisition terminal of each system is communicated with the central processing unit through a matched synchronous trigger.
An application method of a speed field and temperature field data synchronous parallel acquisition system comprises the following steps:
s10, the synchronous control module provides a phase-locked common clock for each acquisition terminal of the speed field calibration time-post total pressure measurement subsystem and the stable section total pressure and temperature field dynamic data acquisition subsystem so as to ensure that each AD digital instrument is in the same state to be triggered;
s11, 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 digital instrument of each acquisition module after receiving the trigger instruction, the acquisition of a pressure signal and a temperature signal is started, and the clock frequency of each AD digital instrument is synchronized through a phase-locked loop in the acquisition process;
and the pressure signals acquired by the AD digital instruments are used for recording the sampling period number of each AD digital instrument before the current synchronous trigger event occurs through a timestamp counter, and identifying and correcting trigger time errors among different acquisition terminals.
Preferably, the method further comprises: s13, the central processing unit eliminates the delay error of the total pressure of the stable section and the total pressure data after the test section, and the elimination mode comprises the following steps:
s130, during each wind tunnel test, the time scale of each group of data is determined through the synchronous measurement of total pressure and flow field static pressure;
s131, by time scale t corresponding to the total pressure peak value 1 Time scale t corresponding to flow field static pressure peak value 2 To find the delay of the calculated fluctuation and the steady-state pressure fluctuation in the flow fieldTime Δ t = t 1 -t 2 ；
S132, when the central processing unit processes the data of the ith moment, t is selected i Steady state pressure value P corresponding to + Δ t moment k (t i + Δ t) as the total pressure P 0 (t i ) And (4) correspondingly, the steady-state pressure value is used for eliminating the delay error.
Preferably, the method further comprises:
s133, taking P k (t i + Δ t) is P 0 (t i ) P corresponding to time ti The values are subjected to a velocity field Mach number calculation, where P ti Represents the total pressure after the ith point wave, P k Representing a kth post-wave total pressure measurement point;
in the computation of the Mach number of the velocity field, based on the total pressure of the antechamber and the total pressure after each measuring point, the Mach number M of the velocity field of the measuring point is solved by adopting a normal shock wave iterative formula of a formula I;
in the formula I, the first step is carried out,
，
，P 0 indicating the total pressure of the front chamber, P ti Represents the total pressure after the ith point wave, M i The mach number that participates in the iteration is represented,
is to M i The function of the iteration is performed as a function,
is at M i Increasing step values on an iterative basis
The latter iteration function.
Preferably, the method further comprises the following steps:
s134, calculating a temperature field temperature value based on the Mach number M of the measuring point obtained by calculation in S133;
when the Mach number =5 and 6, the measuring point temperature T _ i is calculated according to the following fitting formula:
T_i=273.745612+k_1*e+k_2*e^2-k_3*e^3+k_4*e^4-k_5*e^5+k_6*e^6-k_7*e^7+k_8*e^8-k_9*e^9-T_0；
in the first fitting formula, e is a temperature sensor signal output value, k _1 to k _9are temperature fitting coefficients, and T _0 is a reference temperature;
when the Mach number is more than 6, the measuring point temperature T _ i is calculated according to the following fitting mode:
T_i=273.745612-131.8058+k_1*e-k_2*e^2+k_3*e^3-k_4*e^4+k_5*e^5-k_6*e^6-T_0。
the invention at least comprises the following beneficial effects: the system can synchronously and parallelly acquire the test speed field data and the dynamic data of the temperature field of different acquisition systems in the hypersonic wind tunnel test, and can effectively ensure the acquisition accuracy and the time domain correlation of the data.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
FIG. 1 is a schematic diagram of a velocity field calibration of a hypersonic wind tunnel in the prior art;
FIG. 2 is a schematic diagram of a data acquisition delay error of an electronic pressure scanning valve in the prior art;
FIG. 3 is a schematic diagram of the triggering time difference between different acquisition terminals of a pressure scanning valve in the prior art;
FIG. 4 is a schematic diagram of the present invention for eliminating total pressure of the stable section and total pressure conduction delay error after the test section;
FIG. 5 is a block diagram of the system of the present invention;
FIG. 6 is a block diagram of the components of one of the subsystems of the present invention;
FIG. 7 is a diagram illustrating the time delay of data acquisition by different systems in the prior art;
FIG. 8 is a schematic diagram of the present invention during data acquisition in a different system;
the system comprises a wave-backward total pressure measurement subsystem-1, a stable section total pressure and temperature field dynamic data acquisition subsystem-2, an acquisition terminal-10, an acquisition unit-11, an AD digital instrument-12, a phase-locked loop-13, an external synchronous control module-3, a central processing unit-4 and a pressure controller-5.
Detailed Description
The present invention is described in further detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.
It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.
As shown in fig. 5-6, a system for synchronously acquiring data of a velocity field and a temperature field comprises a velocity field calibration time-wave rear total pressure measurement subsystem 1 and a stable section total pressure and temperature field dynamic data acquisition subsystem 2 which are independent of each other;
in the test section, a measurement bent frame (not shown) for measuring total pressure and total temperature is integrally arranged, and in the structure, the total temperature and the total pressure are measured at one position so as to reduce measurement result deviation caused by measurement time sequence and position;
the system comprises at least one acquisition terminal 10, an AD (analog-digital) instrument 12 with an independent and same type and a phase-locked loop 13, wherein each acquisition unit 11 in each acquisition terminal is provided with the AD digitizer 12, and a time stamp counter is integrated in a processor of the AD digitizer;
the external synchronous control module 3 which is matched with each subsystem provides a synchronous clock after phase locking for each acquisition terminal;
the acquisition terminals of the systems communicate with the central processing unit 4 through cooperating synchronization triggers (not shown).
In the specific implementation of the post-wave total pressure measurement subsystem of the scheme, each acquisition unit is configured to include:
at least one pressure sensor matched with the point to be detected on the air path connecting assembly;
the signal conditioning circuit is in communication connection with each pressure sensor to construct a corresponding measuring channel;
the pressure measurement assembly is in communication connection with each first signal conditioning circuit so as to realize synchronous acquisition of each pressure sensor, and the modular design is adopted, so that the interface is expandable and the overall technical index of the system is not influenced;
each acquisition terminal is configured to include:
a pressure measurement machine case (not shown) for carrying out the integration to each pressure measurement subassembly, be provided with the first controller of taking operating system in it, each pressure measurement subassembly inserts pressure measurement machine case, accomplish pressure measurement's modularization integration, the machine case is 4U standard frame machine cases, join in marriage a core control ware slot, can insert 8 collection integrated boards at most, first machine case plug-in card adopts fast inserting structure, the panel has locking screw, can consolidate the integrated board installation after screwing up, core control ware is steady state pressure measurement system's core component, be equivalent to collection equipment's CPU and mainboard, can accomplish functions such as data acquisition management, acquisition command send, data transmission. The operating system of the core controller is an RT real-time operating system. When the real-time operating system interacts with external data, the real-time operating system can process the data at a high enough speed, the processing result can control the production process or make a quick response to the processing system within a specified time, all available resources are scheduled to complete real-time tasks, and all the real-time tasks are controlled to be coordinated and operated in a consistent manner. Compared with a time-sharing operating system, the system has the advantages of timely response and high reliability. For the data acquisition processing server, the synchronous acquisition component is like a black box, a preset program in the core controller automatically calls and operates a synchronous acquisition function, an acquisition instruction sent by the server is received by adopting a driving program, and acquired data are sent to the data acquisition processing server;
and the pressure controller 5 is connected with each pressure measurement component to provide standard pressure, and the portable pressure controller mainly outputs one standard pressure to provide a standard pressure source so as to conveniently finish the checking and troubleshooting work of the pressure scanning valve module. In the scheme, the parameter indexes of the pressure measurement components need to meet the requirements of table 1, and the parameter indexes of the total pressure and temperature field dynamic data acquisition subsystem of the stable section need to meet the requirements of table 2, so that the capability of phase synchronization high-precision acquisition between measuring points and between the pressure measurement components and the total pressure and temperature field dynamic data acquisition subsystem of the stable section is achieved;
TABLE 1
TABLE 2
Each pressure measurement assembly is configured to include:
the first FPGA is used for processing and outputting the signal input by the signal conditioning circuit;
the first phase-locked loop PLL is in communication connection with the first FPGA, the first clock management module and the CPU;
the external communication interface, the synchronous clock signal and the synchronous trigger signal are in communication connection with the first clock management module and the CPU through a control bus;
the central processing unit (also referred to as a control unit) is configured to include:
the frame is provided with a front panel with a signal interface;
the second FPGA is arranged inside the rack;
the second phase-locked loop PLL is in communication connection with the second FPGA, the second clock management module and the synchronous signal generator;
the control unit is in communication connection with each pressure measurement component and each dynamic data acquisition component in the total pressure and temperature field dynamic data acquisition subsystem of the stabilization section through a shunt, the overall structural design of the control unit adopts a 1U rack type structure, a signal interface is configured on a front panel and can be accessed to input and output signals, a synchronization module is in communication with an upper computer through a USB port, hardware equipment in the system adopts an embedded type framework based on FPGA, and the hardware framework based on FPGA + AD has high real-time performance meeting test conditions, can realize acquisition and storage of signals, and has the advantages of strong synchronism, low power consumption, high reliability and the like; the control unit is used as an external trigger source and synchronously accessed to a plurality of acquisition terminals through a splitter to realize the layout of synchronous triggering of a plurality of devices;
each measuring unit of the scheme adopts a modular design, and the modules have independent functions and are not coupled. The modular design is easy to expand the system capacity and improve the maintenance efficiency.
The FGPA realizes the operations of data acquisition, data processing, data transmission and the like in the FPGA through a standard PCIe interface. The method is divided into the following steps according to functions: the data exchange system comprises an interface unit, a processing unit, an output unit and the like, wherein a data flow driving mode is adopted among the units, and after the data processing of the unit is completed, the data are packaged and sent to the next level, so that the data exchange is realized inside the framework.
The FPGA design elements comprise interface design, clock design, reset design, function design and the like. The interface design criteria are: excessive logic is not added, and the influence on the interface time sequence after the added logic is jammed is avoided; clocks include logic clocks, interface clocks, memory clocks, and the like. The logic clock depends on the critical path of the logic, and the product performance is improved. When the FPGA realizes the synchronous signal time sequence, the synchronous adoption of the interface is realized by adopting a fixed and accurate interface clock. The memory clock realizes the data synchronous cache, and the data loss or instability caused by the refreshing frequency is avoided during the design; the internal reset of the FPGA comprises hard reset, logic reset, soft reset and the like. The hard reset is introduced into the external pin and is given in when the power is on, so that the whole FPGA reaches a stable state after the logic configuration is completed. The logic reset is generated by the internal logic of the FPGA and is used for setting the preparation state of signals such as synchronous control and the like. The soft reset is used in a debugging stage, and the soft reset is inserted into a point to be tested, a fault locating point and the like, so that the problem of segmentation can be quickly positioned, and the debugging speed is accelerated. The function design comprises the functions of signal acquisition, signal conditioning, synchronous control, data transmission and the like through the FPGA. The principle of functional design is stable and efficient, and the required circuit realization function and the constraint conditions for realizing the circuit, such as speed, power consumption, circuit type and the like, are comprehensively considered.
And a further stable section total pressure and temperature field dynamic data acquisition subsystem is used for measuring dynamically changed data, an acquisition terminal of the subsystem is similar to a corresponding acquisition unit and a speed field calibration time wave total pressure measurement subsystem, in different acquisition units, in order to realize acquisition of different data, a pressure sensor of a pressure measurement assembly in the wave-rear total pressure measurement subsystem is replaced by a temperature sensor of a dynamic data acquisition assembly in the stable section total pressure and temperature field dynamic data acquisition subsystem, and therefore, the structure of the dynamic data acquisition assembly is not further described.
The implementation mode of the invention is as follows:
1. realize the simultaneous collection of total pressure and temperature after wave
The total pressure bent frame and the total temperature bent frame are combined into one, and the measurement of the total pressure and the temperature after wave-comparing is realized on one bent frame;
2. high-precision synchronization of electronic pressure scanning valve and voltage signal acquisition system
1. Each acquisition unit in each acquisition terminal in the electronic pressure scanning valve measurement system and the voltage signal data acquisition system uses an independent AD (analog-to-digital) digitizer and performs phase locking, so that the clock frequencies of the AD digitizers of all the acquisition units are completely consistent, and the phases of the AD digitizers do not deviate along with time;
2. the external synchronous control module provides a phase-locked synchronous clock for each acquisition terminal of the electronic pressure scanning valve measurement system and the voltage signal acquisition system, and is used for ensuring that an AD (analog-digital) instrument of each acquisition unit in each acquisition terminal of the two systems is in the same state to be triggered;
3. providing a synchronous trigger for each acquisition terminal of the two systems through an external synchronous control module, and determining the starting point of data recorded by the AD digitizer of each acquisition unit in each acquisition terminal;
4. a time stamp counter is introduced into each AD digital instrument, and the time stamp counter records the sampling period number of the AD digital instrument in each acquisition unit before the synchronous trigger event occurs so as to identify and correct the trigger time error among different acquisition units.
3. Eliminating total pressure of stable section and total pressure data delay after test section
Firstly, during each wind tunnel test, the time scale of each group of data is determined through the synchronous measurement of total pressure and flow field static pressure; secondly, the total pressure peak value is corresponding to a time scale t 1 Corresponding time scale t with flow field static pressure peak value 2 Determining the time delay delta t = t of total pressure fluctuation and steady-state pressure fluctuation in the flow field 1 -t 2 (ii) a Finally, in data processing, t is selected i Steady state pressure value P corresponding to + Δ t moment k (t i + Δ t) as the total pressure P 0 (t i ) The error of conduction delay between the total pressure and the flow field steady-state pressure can be effectively eliminated by the corresponding steady-state pressure value.
As shown in fig. 7-8, compared with the existing method, the synchronous acquisition system of the present invention can realize synchronous acquisition of different measurement data of different systems, control delay and error, and ensure that the measurement accuracy meets the test requirements.
4. Completing the calculation of the speed field and the temperature field of the test section
1. Velocity field mach number calculation
According to total pressure P of front chamber 0 And total pressure P after each measuring point wave measured by the total pressure bent frame ti And solving the Mach number (M) of the measuring point according to a normal shock wave iterative formula, wherein the iterative formula is as follows:
in the formula I, the first step is carried out,
，
，P 0 representing the total pressure of the front chamber, P ti Represents the total pressure after the ith point wave, M i The mach number of the participation in the iteration is indicated,
is to M pair i The function of the iteration is carried out as a function,
is at M i Increasing step values on an iterative basis
The latter iteration function.
Here, according to the method in the third item above, take P k (t i + Δ t) as P 0 (t i ) P corresponding to time ti The value is obtained. P is k Representing the kth post-wave total pressure measurement point.
2. Temperature field temperature value calculation
When mach number =5, 6, the measuring point temperature T _ i is calculated according to the following fitting formula:
T_i=273.745612+k_1*e+k_2*e^2-k_3*e^3+k_4*e^4-k_5*e^5+k_6*e^6-k_7*e^7+k_8*e^8-k_9*e^9-T_0；
in the formula: e is the temperature sensor signal output value, and the unit is millivolt (mV); k _1 to k \ u 9 are temperature fitting coefficients; t _0 is a reference temperature.
When the Mach number is more than 6, the measuring point temperature T _ i is calculated according to the following fitting mode:
T_i=273.745612-131.8058+k_1*e-k_2*e^2+k_3*e^3-k_4*e^4+k_5*e^5-k_6*e^6-T_0；
in the formula: e is the temperature sensor signal output value in millivolts (mV); k 1 to k \9are temperature fitting coefficients; t _0 is a reference temperature.
3. The model area temperature field distribution evaluation formula is as follows:
in the formula:
is the average temperature; n is the number of the measuring points; t is a unit of i The temperature of the measuring point is measured; delta T 0max Is the maximum deviation of temperature; σ is the mean square error of the temperature field. When the gradient of the temperature field is calculated, n represents the number of sections; x i Denotes the distance, T, of the i-th cross-section from the entrance of the test section i Representing the cross-sectional mach number.
4. Completing high ultrasonic speed hot complete gas correction when Mach number is more than 8
Calculating a correction coefficient f according to the following formula 1 And f 2 And finishing the correction of the incoming flow static pressure, the speed pressure and the Reynolds number according to the correction coefficient.
In the formula: gamma is the gas specific heat ratio; t is a unit of 0 Is the total temperature; m is Mach number.
The above scheme is merely illustrative of a preferred example, and is not limiting. In the implementation of the invention, appropriate replacement and/or modification can be carried out according to the requirements of users.
The number of apparatuses and the scale of the process described herein are intended to simplify the description of the present invention. Applications, modifications and variations of the present invention will be apparent to those skilled in the art.
While embodiments of the invention have been disclosed above, it is not intended to be limited to the uses set forth in the specification and examples. It can be applied to all kinds of fields suitable for the present invention. Additional modifications will readily occur to those skilled in the art. Therefore, the invention is not to be limited to the specific details and illustrations shown and described herein, without departing from the general concept as defined by the claims and their equivalents.
Claims (3)
1. A synchronous parallel acquisition system for speed field and temperature field data is characterized by comprising a speed field calibration time-wave rear total pressure measurement subsystem, a stable section total pressure and temperature field dynamic data acquisition subsystem which are mutually independent;
in the test section, a measurement bent frame for measuring the total pressure and the total temperature after the wave is measured is integrally arranged;
the system comprises a plurality of subsystems, a phase-locked loop and a clock signal acquisition unit, wherein each subsystem is respectively provided with at least one acquisition terminal, each acquisition unit in each acquisition terminal uses an independent AD digital instrument with the same type and is phase-locked through a phase-locked loop, and a processor of the AD digital instrument is integrated with a timestamp counter;
each subsystem provides a phase-locked synchronous clock for each acquisition terminal through a matched external synchronous control module;
each acquisition terminal of each system is communicated with the central processing unit through a matched synchronous trigger;
the application method of the speed field and temperature field data synchronous parallel acquisition system comprises the following steps:
s10, the synchronous control module provides a phase-locked common clock for each acquisition terminal of the speed field calibration time-post total pressure measurement subsystem and the stable section total pressure and temperature field dynamic data acquisition subsystem so as to ensure that each AD digital instrument is in the same state to be triggered;
s11, 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 module after receiving the trigger instruction, the acquisition of pressure signals and temperature signals is started, and the clock frequency of each AD digitizer is synchronized through a phase-locked loop in the acquisition process;
the pressure signals acquired by the AD digital instruments are used for recording the sampling period number of each AD digital instrument before the current synchronous trigger event occurs through a timestamp counter, and identifying and correcting trigger time errors among different acquisition terminals;
further comprising:
s13, the central processing unit eliminates the delay error of the total pressure of the stable section and the total pressure data after the test section, and the elimination mode comprises the following steps:
s130, during each wind tunnel test, determining the time scale of each group of data through synchronous measurement of total pressure of the stable section and static pressure of the flow field;
s131, a time scale t corresponding to the total pressure peak value of the stable section is used 1 Time scale t corresponding to flow field static pressure peak value 2 Calculating the total pressure of the stable section and the time delay delta t = t of the steady-state pressure fluctuation in the flow field 1 -t 2 ；
S132, when the central processing unit processes the data of the ith moment, t is selected i Steady state pressure value P corresponding to + Δ t moment k (t i + Δ t) as the total pressure P 0 (t i ) And (4) correspondingly, the steady-state pressure value is used for eliminating the delay error.
2. The method for applying the system for synchronously and parallelly acquiring the data of the speed field and the temperature field according to claim 1, further comprising the following steps of:
in the computation of the Mach number of the velocity field, based on the total pressure of the antechamber and the total pressure after each measuring point, the Mach number M of the velocity field of the measuring point is solved by adopting a normal shock wave iterative formula of a formula I;
in the formula, the content of the active carbon is shown in the specification,
，
，P 0 representing the total pressure of the front chamber, P ti Denotes the ith Point-wave Total pressure, M i The mach number that participates in the iteration is represented,
is to M pair i The function of the iteration is performed as a function,
is at M i Increasing step values on an iterative basis
The latter iteration function.
3. The method for applying the system for synchronously and parallelly acquiring the data of the speed field and the temperature field according to claim 2, further comprising the following steps:
s134, calculating a temperature field temperature value based on the Mach number M of the measuring point obtained by calculation in S133;
when the Mach number =5 and 6, the measuring point temperature T _ i is calculated according to the following fitting formula:
T_i=273.745612+k_1*e+k_2*e^2-k_3*e^3+k_4*e^4-k_5*e^5+k_6*e^6-k_7*e^7+k_8*e^8-k_9*e^9-T_0；
in the first fitting formula, e is a temperature sensor signal output value, k _1 to k _9are temperature fitting coefficients, and T _0 is a reference temperature;
when the Mach number is larger than 6, the temperature T _ i of the measuring point is calculated according to the fitting formula below:
T_i=273.745612-131.8058+k_1*e-k_2*e^2+k_3*e^3-k_4*e^4+k_5*e^5-k_6*e^6-T_0。
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