CN112326184A - Frequency-variable high-precision wind tunnel test data acquisition method - Google Patents

Frequency-variable high-precision wind tunnel test data acquisition method Download PDF

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CN112326184A
CN112326184A CN202011338707.5A CN202011338707A CN112326184A CN 112326184 A CN112326184 A CN 112326184A CN 202011338707 A CN202011338707 A CN 202011338707A CN 112326184 A CN112326184 A CN 112326184A
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frequency
acquisition
data
sampling rate
collection
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CN112326184B (en
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唐亮
周润
李平
黄叙辉
蒋鸿
高鹏
王博文
蒋靖妍
汤宏宇
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Ultra High Speed Aerodynamics Institute China Aerodynamics Research and Development Center
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Abstract

The invention discloses a frequency-variable high-precision wind tunnel test data acquisition method, which comprises the following steps: carrying out sampling rate and acquisition point coarse screening, generating a plurality of groups of sampling rate and acquisition point schemes according to data storage frequency and acquisition card performance, and carrying out acquisition calibration to obtain the precision result of each group of sampling rate and acquisition point; carrying out sampling rate and acquisition point fine screening, selecting two groups of sampling rates with highest precision and acquisition points to form an upper limit and a lower limit, generating a plurality of groups of sampling rate and acquisition point schemes, carrying out acquisition calibration to obtain precision results of each group of sampling rates and acquisition points, and selecting the scheme with highest precision as the optimal sampling rate and acquisition points of the storage frequency; storing filtering data at low frequency when the wind tunnel is in a turning state; and when the wind tunnel is in a test state, storing filtering data and non-filtering data at high frequency respectively. The invention improves the accuracy of data acquisition, expands the data storage quantity and improves the utilization rate of the stored data.

Description

Frequency-variable high-precision wind tunnel test data acquisition method
Technical Field
The invention belongs to the technical field of wind tunnel experiment data acquisition, and particularly relates to a frequency-variable high-precision wind tunnel experiment data acquisition method.
Background
At present, the data acquisition method applied to the wind tunnel test mainly comprises two methods of single-point acquisition and continuous acquisition.
Single point acquisition is the test data acquisition mode adopted by most wind tunnels at present. The specific method is that after a wind tunnel test is started, the wind tunnel reaches a preset state (total pressure, Mach number, model attack angle and the like reach preset values), single-point data is collected, and the single-point data is generally average in collection values for 10-50 times. After the collection is finished, the wind tunnel is adjusted to the next preset state, and then single-point data are collected. Typically 10 single points of data are stored for a single experiment. The single-point data has the defects that firstly, data samples are few, only a preset state has a collection value, the test data condition cannot be monitored in real time, secondly, the collection time is short, and if a data collection time period model vibrates, the attack angle is over large in deviation, and the data collection precision is influenced.
At present, part of wind tunnels adopt a continuous acquisition method. The method comprises the steps of starting continuous acquisition after a wind tunnel test is started, and marking data positions of preset state time periods in continuous data when the wind tunnel reaches preset states (total pressure, Mach number, model attack angle and the like). The method has the advantages that a plurality of data samples are stored, and the test data condition can be monitored in real time; the method has the disadvantages that the conventional method adopts fixed frequency acquisition, for example, the sampling rate is set to be 2kHz, the number of acquisition points is set to be 200, and 200 points of data are acquired every 0.1s to obtain an average data. The method is not suitable for storing data for a long time and is difficult to be applied to the continuous wind tunnel. And the sampling rate is set according to manual experience, and the influence of the setting of the sampling rate and the collection point number on the collection precision is not verified.
Regardless of a single-point acquisition scheme and a continuous acquisition method, acquired data are data subjected to low-frequency filtering by hardware equipment, and the filtering data are difficult to analyze state information such as model vibration frequency.
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.
To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided a frequency-variable high-precision wind tunnel test data acquisition method, including:
step one, when the continuous wind tunnel operates, variable frequency data are stored according to the rotating speed of a compressor, namely when the compressor operates in a turning gear mode, the wind tunnel is not in a test state at the moment, and filtering data are stored by adopting low frequency; when the wind tunnel enters a test state, storing filtering data by adopting high frequency, and storing non-filtering data at the same time; the collected and stored data is one or more of force, pressure and temperature;
step two, testing to obtain the optimal sampling rate and the optimal number of the acquisition points according to the data storage frequency and the sampling rate capability of the acquisition card, and the specific steps comprise:
step S21, roughly screening the sampling rate and the collection points, generating a plurality of groups of sampling rates and collection point schemes of the storage frequency according to the relationship that the data storage frequency and the sampling rate capability of the collection card and the storage frequency are equal to the sampling rate divided by the collection points, collecting and calibrating by using a standard signal source as an input signal, and obtaining the accuracy of each group of sampling rate and collection points;
s22, obtaining the accuracy of each group of sampling rate and collection point through S21, selecting two groups of sampling rate and collection point with the highest accuracy to form an upper limit and a lower limit, setting a plurality of groups of sampling rate and collection point schemes of the storage frequency between the upper limit and the lower limit of the sampling rate and the collection point, and finely screening the sampling rate and the collection point; using a standard signal source as an input signal, carrying out acquisition calibration, and selecting a scheme of sampling rate with highest precision and acquisition points as the sampling rate and the acquisition points of the storage frequency;
step S23, obtaining the optimal sampling rate and the collection points in the low-frequency storage mode and the high-frequency storage mode;
step three, when the wind tunnel compressor is in low-speed turning operation, acquiring data according to a scheme of optimal sampling rate and acquisition points corresponding to low-frequency storage frequency, and continuously storing filtering data according to the frequency; in the high-rotating-speed test state of the wind tunnel, the scheme of the optimal sampling rate and the collection point number corresponding to the high-frequency storage frequency is used for collecting data, filtering data are stored, and meanwhile, non-filtering data are stored at a frequency higher than a specific frequency.
Preferably, the frequency of the low-frequency preservation filtering data is 1Hz to 5 Hz; the frequency of the high-frequency stored filtering data is 10 Hz-60 Hz; the specific frequency is 100Hz or higher.
Preferably, the specific method for roughly screening the sampling rate and the number of collected points in step S21 is as follows: taking the number of the acquisition points 1 as a lower limit, the highest sampling rate of the acquisition card as an upper limit, and the target storage frequency as xHz, then for the set N groups of the acquisition points: p is a radical of1,p2,...,pnWherein p is11, N is more than or equal to 1, and each group of collection points is provided with a corresponding sampling rate: p is a radical of1x,p2x·,...,pnx, wherein pnx is equal to the highest sampling rate of the acquisition card; obtaining N groups of collection point number and sampling rate schemes: (p)1,p1x),(p2,p2x),...,(pn,pnx) carrying out acquisition calibration by using the standard signal source according to the N schemes to obtain respective accuracy.
Preferably, the specific method for performing the sampling rate and the collection point number fine screening in step S22 includes: selection (p)1,p1x),(p2,p2x),...,(pn,pnx) two groups of collection point number schemes with highest precision: (p)i,pix),(pj,pjx),pi<pjTo (p)i,pix) is a lower limit, in (p)j,pjx) is an upper limit, and N is automatically generated1Group sampling rate and collection point numberA scheme: (p)i,pix),(pi1,pi1x),...,(pj,pjAnd x), correcting the N sets of schemes by using a standard signal source to carry out acquisition calibration so as to obtain respective acquisition accuracy, and taking the scheme with the highest accuracy as the frequency sampling rate and the acquisition points.
Preferably, the step of performing acquisition calibration using a standard signal source comprises:
step A, outputting a standard voltage signal to an acquisition card by using a standard signal source, wherein the range of the acquisition card is Vl~VhOutput voltage of VlAt a lower limit of VhAs an upper limit, sequentially recording t +1 equal-difference voltage values with equal intervals: vl,Vl+d,...,Vl+(t-1)d,VhWhere t > 10, d ═ Vh-Vl) T; when the voltage value is stably output, the acquisition card acquires and stores data for 5 times;
step B, the standard signal source is reversed in the direction Vh,Vl+(t-1)d,...,Vl+d,VlThe interval sequence stably outputs voltage signals, and a collection card collects and stores data;
c, repeating the step A and the step B, and completing data acquisition and storage of more than two times of positive and negative strokes;
and D, calculating sampling accuracy by taking the standard output voltage value of the standard signal source and the actual acquisition voltage value of the acquisition card as comparison.
Preferably, the process of collecting the voltage signal by the collecting card is as follows: after the sensor measures and obtains a wind tunnel test force signal, a pressure signal or a temperature signal, the sensor transmits a weak voltage signal to the signal conditioner, the signal conditioner outputs a filtering voltage signal and a non-filtering voltage signal respectively after isolating and amplifying the weak voltage signal through the signal conditioner, the filtering voltage signal and the non-filtering voltage signal are collected by the collection card, and finally the collection card outputs a digital signal to the computer.
Preferably, the method for calculating the accuracy of the acquisition card in the step D comprises: the positive direction output voltage value sequence of the standard signal source is as follows:
Vl,Vl+d,...,Vl+(t-1)d,Vh,Vl+(t-1)d,...,Vl+d,Vl,Vl+d,...,Vl+(t-1)d,Vh,Vl+(t-1)d,...,Vl+d,Vl
when each sequence value is output, the standard signal source and the acquisition card simultaneously record data for 5 times, and the data recorded by the standard signal source is recorded as x1,...x20t+5Data recorded as y for the acquisition card1,...y20t+5And performing linear fitting on the data record values by using a least square method, wherein the slope k and the intercept b are calculated according to the following formula:
Figure BDA0002798001150000041
Figure BDA0002798001150000042
calculating the sample variance S of the acquired data on a least square normal linear fitting line according to the following formula2. By sample variance S2To judge the data accuracy, S, of the sequence acquisition card2The smaller the acquisition card precision is, the higher:
Figure BDA0002798001150000043
the method comprises the steps of firstly, selecting two groups of schemes with the highest sampling precision as upper and lower limits of a sampling rate and a collection point fine screen, automatically generating multiple groups of sampling rates and collection point schemes, then, using a standard signal source to carry out collection calibration, calculating the collection precision of each group of schemes, and taking the scheme with the highest precision as the optimal sampling rate and collection point of the given storage frequency.
The invention at least comprises the following beneficial effects:
(1) the sampling rate/the number of the acquisition points are set through an experimental method to improve the accuracy of the acquired data; different from the traditional method of configuring the sampling rate and the collection points through manual experience, the scheme obtains the accurate setting of the sampling rate and the collection points in two steps through an experiment verification precision method, and the accurate collection of data is guaranteed.
(2) The test data is detailed and complete; the data under the wind tunnel turning state is used for monitoring the state of the system; and the filtered data in the wind tunnel test state is used for real-time monitoring and test result calculation, and the non-filtered data is used for later analysis application such as later spectrum calculation.
(3) The utilization rate of stored data is improved while the quality and the quantity of the data are ensured; and storing data at a low frequency in a wind tunnel turning gear state and storing data at a high frequency in a test state.
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.
Description of the drawings:
FIG. 1 is a flow chart of setting and calibrating sampling rate and collection point number of the frequency-variable high-precision wind tunnel test data collection method provided by the invention;
FIG. 2 is a flow chart of a frequency-variable high-precision wind tunnel test data acquisition method provided by the invention;
FIG. 3 is a schematic flow chart of a collection card for collecting wind tunnel test data.
The specific implementation mode is as follows:
the present invention is further described in 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.
It is to be understood that in the description of the present invention, the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are used only for convenience in describing the present invention and for simplification of the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, unless otherwise specifically stated or limited, the terms "mounted," "disposed," "sleeved/connected," "connected," and the like are used broadly, and for example, "connected" may be a fixed connection, a detachable connection, or an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, or a communication between two elements, and those skilled in the art will understand the specific meaning of the terms in the present invention specifically.
Further, in the present invention, unless otherwise explicitly specified or limited, a first feature "on" or "under" a second feature may be directly contacted with the first and second features, or indirectly contacted with the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
As shown in fig. 1-2: the invention discloses a frequency-variable high-precision wind tunnel test data acquisition method, which comprises the following steps:
step one, when the continuous wind tunnel operates, variable frequency data are stored according to the rotating speed of a compressor, namely when the compressor operates in a turning gear mode, the wind tunnel is not in a test state at the moment, and filtering data are stored by adopting low frequency; when the wind tunnel enters a test state, storing filtering data by adopting high frequency, and storing non-filtering data at the same time; the collected and stored data is one or more of force, pressure and temperature;
step two, testing to obtain the optimal sampling rate and the optimal number of the acquisition points according to the data storage frequency and the sampling rate capability of the acquisition card, and the specific steps comprise:
step S21, roughly screening the sampling rate and the collection points, generating a plurality of groups of sampling rates and collection point schemes of the storage frequency according to the relationship that the data storage frequency and the sampling rate capability of the collection card and the storage frequency are equal to the sampling rate divided by the collection points, collecting and calibrating by using a standard signal source as an input signal, and obtaining the accuracy of each group of sampling rate and collection points;
s22, obtaining the accuracy of each group of sampling rate and collection point through S21, selecting two groups of sampling rate and collection point with the highest accuracy to form an upper limit and a lower limit, setting a plurality of groups of sampling rate and collection point schemes of the storage frequency between the upper limit and the lower limit of the sampling rate and the collection point, and finely screening the sampling rate and the collection point; using a standard signal source as an input signal, carrying out acquisition calibration, and selecting a scheme of sampling rate with highest precision and acquisition points as the sampling rate and the acquisition points of the storage frequency;
step S23, obtaining the optimal sampling rate and the collection points in the low-frequency storage mode and the high-frequency storage mode;
step three, when the wind tunnel compressor is in low-speed turning operation, acquiring data according to a scheme of optimal sampling rate and acquisition points corresponding to low-frequency storage frequency, and continuously storing filtering data according to the frequency; in the high-rotating-speed test state of the wind tunnel, the scheme of the optimal sampling rate and the collection point number corresponding to the high-frequency storage frequency is used for collecting data, filtering data are stored, and meanwhile, non-filtering data are stored at a frequency higher than a specific frequency.
In the technical scheme, the frequency of the low-frequency stored filtering data is 1 Hz-5 Hz; the frequency of the high-frequency stored filtering data is 10 Hz-60 Hz; the specific frequency is 100Hz or higher.
In the above technical solution, the specific method for coarse screening the sampling rate and the number of the collection points in step S21 includes: taking the number of the acquisition points 1 as the lower limit, the highest sampling rate of the acquisition card as the upper limit and the target storage frequency as xHz, setting the target storage frequencyN sets of collection points: p is a radical of1,p2,...,pnWherein p is11, N is more than or equal to 1, and each group of collection points is provided with a corresponding sampling rate: p is a radical of1x,p2x·,...,pnx, wherein pnx is equal to the highest sampling rate of the acquisition card; obtaining N groups of collection point number and sampling rate schemes: (p)1,p1x),(p2,p2x),...,(pn,pnx) carrying out acquisition calibration by using the standard signal source according to the N schemes to obtain respective accuracy.
In the above technical solution, the specific method for performing fine screening on the sampling rate and the number of the collected points in the step S22 includes: selection (p)1,p1x),(p2,p2x),...,(pn,pnx) two groups of collection point number schemes with highest precision: (p)i,pix),(pj,pjx),pi<pjTo (p)i,pix) is a lower limit, in (p)j,pjx) is an upper limit, and N is automatically generated1Group sampling rate and acquisition point number scheme: (p)i,pix),(pi1,pi1x),...,(pj,pjAnd x), correcting the N sets of schemes by using a standard signal source to carry out acquisition calibration so as to obtain respective acquisition accuracy, and taking the scheme with the highest accuracy as the frequency sampling rate and the acquisition points.
In the above technical solution, the step of using the standard signal source to perform the acquisition calibration includes:
step A, outputting a standard voltage signal to an acquisition card by using a standard signal source, wherein the range of the acquisition card is Vl~VhOutput voltage of VlAt a lower limit of VhAs an upper limit, sequentially recording t +1 equal-difference voltage values with equal intervals: vl,Vl+d,...,Vl+(t-1)d,VhWhere t > 10, d ═ Vh-Vl) T; when the voltage value is stably output, the acquisition card acquires and stores data for 5 times;
step B, the standard signal source is reversed in the direction Vh,Vl+(t-1)d,...,Vl+d,VlSpacer sequenceStably outputting voltage signals, and acquiring and storing data by an acquisition card;
c, repeating the step A and the step B, and completing data acquisition and storage of more than two times of positive and negative strokes;
and D, calculating sampling accuracy by taking the standard output voltage value of the standard signal source and the actual acquisition voltage value of the acquisition card as comparison.
In the above technical solution, as shown in fig. 3, the process of acquiring the voltage signal by the acquisition card is as follows: after the sensor measures and obtains a wind tunnel test force signal, a pressure signal or a temperature signal, the sensor transmits a weak voltage signal to the signal conditioner, the signal conditioner outputs a filtering voltage signal and a non-filtering voltage signal respectively after isolating and amplifying the weak voltage signal through the signal conditioner, the filtering voltage signal and the non-filtering voltage signal are collected by the collection card, and finally the collection card outputs a digital signal to the computer.
In the above technical solution, the method for calculating the accuracy of the acquisition card in step D comprises: the positive direction output voltage value sequence of the standard signal source is as follows:
Vl,Vl+d,...,Vl+(t-1)d,Vh,Vl+(t-1)d,...,Vl+d,Vl,Vl+d,...,Vl+(t-1)d,Vh,Vl+(t-1)d,...,Vl+d,Vl
when each sequence value is output, the standard signal source and the acquisition card simultaneously record data for 5 times, and the data recorded by the standard signal source is recorded as x1,...x20t+5Data recorded as y for the acquisition card1,...y20t+5And performing linear fitting on the data record values by using a least square method, wherein the slope k and the intercept b are calculated according to the following formula:
Figure BDA0002798001150000081
Figure BDA0002798001150000082
calculating the sample variance S of the acquired data on a least square normal linear fitting line according to the following formula2. By sample variance S2To judge the data accuracy, S, of the sequence acquisition card2The smaller the acquisition card precision is, the higher:
Figure BDA0002798001150000083
the method comprises the steps of firstly, selecting two groups of schemes with the highest sampling precision as upper and lower limits of a sampling rate and a collection point fine screen, automatically generating multiple groups of sampling rates and collection point schemes, then, using a standard signal source to carry out collection calibration, calculating the collection precision of each group of schemes, and taking the scheme with the highest precision as the optimal sampling rate and collection point of the given storage frequency.
Example (b):
taking the target storage frequency of 10Hz as an example, taking the number of acquisition points 1 as a lower limit, taking the highest sampling rate of 500Ks/s of the acquisition card as an upper limit, and automatically generating 6 groups of sampling rate and acquisition point schemes by a method of multiplying the number of acquisition points each time by 10, as shown in table 1:
TABLE 1 coarse screening scheme for sampling rate and number of collected points
Sampling rate 10 100 1000 10000 100000 500000
Number of collected points 1 10 100 1000 10000 50000
Using a standard signal source to carry out acquisition and calibration on the scheme in the 6, and calculating to obtain respective sampling precision;
selecting two groups of sampling rates and collection point number settings with highest precision, automatically generating 6 groups of sampling rates and collection point numbers by taking the two groups of sampling rates and collection point numbers as upper and lower limits, and performing collection and calibration by using a standard signal source as an input signal to obtain the corresponding precision of each group; for example, if the two sets of sampling rates and collection point schemes with the highest accuracy in table 1 are (100,1000) and (1000,10000), respectively, with 100 collection point lower limits and 1000 as collection point upper limits, 6 sets of collection schemes are generated, as shown in table 2:
TABLE 2 fine screening scheme for sampling rate and number of collection points
Sampling rate 1000 2800 4600 6400 8200 10000
Number of collected points 100 280 460 640 820 1000
And (4) carrying out acquisition calibration according to the 6 sets of schemes to obtain respective accuracy, and saving the sampling rate and the acquisition points under the frequency of 10Hz according to the scheme with the highest accuracy.
According to the method, the calibration obtains the optimal sampling rate and the collection point number of the low-frequency storage mode, such as 1Hz, 2Hz, 3Hz, 4Hz and 5Hz, and the high-frequency storage mode, such as 10Hz, 20Hz, 30Hz, 40Hz, 50Hz and 60 Hz.
A flow chart of setting sampling rate and accuracy of collection points is shown in fig. 1. According to the sampling rate and the collection point number obtained by calibration under each storage frequency, the optimal sampling rate and the collection point number of the respective high-frequency storage mode and low-frequency storage mode are set for wind tunnel test data collection, as shown in fig. 2.
In fig. 2, when the continuous wind tunnel is operated, variable frequency data is stored according to the rotating speed of the compressor, when the rotating speed of the compressor is below 70, the compressor is in turning operation, the wind tunnel is not in a test state at this time, and a low-frequency storage mode is adopted to store data at the frequency of 1Hz to 5 Hz. And when the rotation number of the compressor is more than 70, judging that the wind tunnel enters a test state, and storing data in a high-frequency storage mode at the frequency of 10Hz to 60 Hz.
In the wind tunnel test state, the non-filtering collected data is continuously stored at a collection frequency of more than 100Hz while ensuring the filtering data.
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 described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.

Claims (7)

1. A frequency-variable high-precision wind tunnel test data acquisition method is characterized by comprising the following steps:
step one, when the continuous wind tunnel operates, variable frequency data are stored according to the rotating speed of a compressor, namely when the compressor operates in a turning gear mode, the wind tunnel is not in a test state at the moment, and filtering data are stored by adopting low frequency; when the wind tunnel enters a test state, storing filtering data by adopting high frequency, and storing non-filtering data at the same time; the collected and stored data is one or more of force, pressure and temperature;
step two, testing to obtain the optimal sampling rate and the optimal number of the acquisition points according to the data storage frequency and the sampling rate capability of the acquisition card, and the specific steps comprise:
step S21, roughly screening the sampling rate and the collection points, generating a plurality of groups of sampling rates and collection point schemes of the storage frequency according to the relationship that the data storage frequency and the sampling rate capability of the collection card and the storage frequency are equal to the sampling rate divided by the collection points, collecting and calibrating by using a standard signal source as an input signal, and obtaining the accuracy of each group of sampling rate and collection points;
s22, obtaining the accuracy of each group of sampling rate and collection point through S21, selecting two groups of sampling rate and collection point with the highest accuracy to form an upper limit and a lower limit, setting a plurality of groups of sampling rate and collection point schemes of the storage frequency between the upper limit and the lower limit of the sampling rate and the collection point, and finely screening the sampling rate and the collection point; using a standard signal source as an input signal, carrying out acquisition calibration, and selecting a scheme of sampling rate with highest precision and acquisition points as the sampling rate and the acquisition points of the storage frequency;
step S23, obtaining the optimal sampling rate and the collection points in the low-frequency storage mode and the high-frequency storage mode;
step three, when the wind tunnel compressor is in low-speed turning operation, acquiring data according to a scheme of optimal sampling rate and acquisition points corresponding to low-frequency storage frequency, and continuously storing filtering data according to the frequency; in the high-rotating-speed test state of the wind tunnel, the scheme of the optimal sampling rate and the collection point number corresponding to the high-frequency storage frequency is used for collecting data, filtering data are stored, and meanwhile, non-filtering data are stored at a frequency higher than a specific frequency.
2. The variable-frequency high-precision wind tunnel test data acquisition method according to claim 1, wherein the frequency of the low-frequency stored filter data is 1Hz to 5 Hz; the frequency of the high-frequency stored filtering data is 10 Hz-60 Hz; the specific frequency is 100Hz or higher.
3. The frequency-variable high-precision wind tunnel test data acquisition method according to claim 1, wherein the specific method for performing rough screening on the sampling rate and the acquisition point number in step S21 is as follows: taking the number of the acquisition points 1 as a lower limit, the highest sampling rate of the acquisition card as an upper limit, and the target storage frequency as xHz, then for the set N groups of the acquisition points: p is a radical of1,p2,...,pnWherein p is11, N is more than or equal to 1, and each group of collection points is provided with a corresponding sampling rate: p is a radical of1x,p2x·,...,pnx, wherein pnx is equal to the highest sampling rate of the acquisition card; obtaining N groups of collection point number and sampling rate schemes: (p)1,p1x),(p2,p2x),...,(pn,pnx) carrying out acquisition calibration by using the standard signal source according to the N schemes to obtain respective accuracy.
4. The frequency-variable high-precision wind tunnel test data acquisition method according to claim 3, wherein the specific method for performing sampling rate and acquisition point number fine screening in step S22 comprises: selection (p)1,p1x),(p2,p2x),...,(pn,pnx) two groups of collection point number schemes with highest precision: (p)i,pix),(pj,pjx),pi<pjTo (p)i,pix) is a lower limit, in (p)j,pjx) is an upper limit, and N is automatically generated1Group sampling rate and acquisition point number scheme: (p)i,pix),(pi1,pi1x),...,(pj,pjAnd x), correcting the N sets of schemes by using a standard signal source to carry out acquisition calibration so as to obtain respective acquisition accuracy, and taking the scheme with the highest accuracy as the frequency sampling rate and the acquisition points.
5. The method for collecting data of a variable frequency high precision wind tunnel test according to claim 1, wherein the step of collecting and calibrating the data using a standard signal source comprises:
step A, outputting a standard voltage signal to an acquisition card by using a standard signal source, wherein the range of the acquisition card is Vl~VhOutput voltage of VlAt a lower limit of VhAs an upper limit, sequentially recording t +1 equal-difference voltage values with equal intervals: vl,Vl+d,...,Vl+(t-1)d,VhWhere t > 10, d ═ Vh-Vl) T; when the voltage value is stably output, the acquisition card acquires and stores data for 5 times;
step B, the standard signal source is reversed in the direction Vh,Vl+(t-1)d,...,Vl+d,VlThe interval sequence stably outputs voltage signals, and a collection card collects and stores data;
c, repeating the step A and the step B, and completing data acquisition and storage of more than two times of positive and negative strokes;
and D, calculating sampling accuracy by taking the standard output voltage value of the standard signal source and the actual acquisition voltage value of the acquisition card as comparison.
6. The frequency-variable high-precision wind tunnel test data acquisition method according to claim 1, wherein the process of acquiring the voltage signal by the acquisition card is as follows: after the sensor measures and obtains a wind tunnel test force signal, a pressure signal or a temperature signal, the sensor transmits a weak voltage signal to the signal conditioner, the signal conditioner outputs a filtering voltage signal and a non-filtering voltage signal respectively after isolating and amplifying the weak voltage signal through the signal conditioner, the filtering voltage signal and the non-filtering voltage signal are collected by the collection card, and finally the collection card outputs a digital signal to the computer.
7. The frequency-variable high-precision wind tunnel test data acquisition method according to claim 5, wherein the method for calculating the accuracy of the acquisition card in the step D comprises: the positive direction output voltage value sequence of the standard signal source is as follows:
Vl,Vl+d,...,Vl+(t-1)d,Vh,Vl+(t-1)d,...,Vl+d,Vl,Vl+d,...,Vl+(t-1)d,Vh,Vl+(t-1)d,...,Vl+d,Vl
when each sequence value is output, the standard signal source and the acquisition card simultaneously record data for 5 times, and the data recorded by the standard signal source is recorded as x1,...x20t+5Data recorded as y for the acquisition card1,...y20t+5And performing linear fitting on the data record values by using a least square method, wherein the slope k and the intercept b are calculated according to the following formula:
Figure RE-FDA0002865315020000031
Figure RE-FDA0002865315020000032
calculating the sample variance S of the acquired data on a least square normal linear fitting line according to the following formula2By the sample variance S2To judge the data accuracy, S, of the sequence acquisition card2The smaller the acquisition card precision is, the higher:
Figure RE-FDA0002865315020000033
the method comprises the steps of firstly, selecting two groups of schemes with the highest sampling precision as upper and lower limits of a sampling rate and a collection point fine screen, automatically generating multiple groups of sampling rates and collection point schemes, then, using a standard signal source to carry out collection calibration, calculating the collection precision of each group of schemes, and taking the scheme with the highest precision as the optimal sampling rate and collection point of the given storage frequency.
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