CN110542535A - Normalization method for pulse wind tunnel multi-sensor negative pressure test system - Google Patents
Normalization method for pulse wind tunnel multi-sensor negative pressure test system Download PDFInfo
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Abstract
the invention provides a normalization method of a pulse wind tunnel multi-sensor negative pressure test system, which comprises the following steps: (1) calibrating and tracing a standard vacuum absolute pressure sensor: the vacuum absolute pressure sensor is sent to more than two levels of metering stations with vacuum pressure calibration quality for calibration; (2) the multi-sensor negative pressure test system is calibrated on site: calibrating the pressure values of all line sensors of the whole test system by taking the vacuum absolute pressure sensor as an intermediary for magnitude transmission, and obtaining the field sensitivity ki (i is 1, 2, … …, n) of each sensor; (3) the actual pressure increment value Δ pi is calculated by multiplying the field sensitivity ki by the output voltage difference Δ Ui during the test. The normalization method can effectively eliminate the system error of each channel of the multi-sensor negative pressure test system, and can greatly improve the reliability and the overall accuracy of the negative pressure test system.
Description
Technical Field
The invention belongs to the technical field of pulse wind tunnel testing, and particularly relates to a normalization method of a pulse wind tunnel multi-sensor negative pressure testing system.
background
In a wind tunnel test multi-channel pressure test system, the electronic pressure scanning valve is widely applied to steady-state pressure test by virtue of excellent performance and has high precision. However, in the pulse wind tunnel, the pressure changes rapidly, the pressure measuring pipeline with a long input end of the electronic pressure scanning valve has long balance time and slow response, and may cause large measurement errors, so the electronic pressure scanning valve is not suitable for a pulse wind tunnel pressure testing system.
in a pulse wind tunnel multi-channel negative pressure (lower than ambient atmospheric pressure) test system, in order to improve the pressure measurement response speed, a high-frequency dynamic absolute pressure sensor needs to be configured for each test channel, the length of a pressure measurement pipe is shortened as much as possible, and even the sensor is directly installed at the near end of a model pressure measurement hole, so that the multi-sensor negative pressure test system is formed.
For the multi-sensor negative pressure test system, the data conversion and transmission process is shown in fig. 2, and each channel includes a plurality of signal conversion and transmission links such as a pressure sensor, a transmission line, a conditioner, and an acquisition instrument. The pressure sensor converts the physical pressure quantity P into a circuit analog quantity A, the circuit analog quantity A is converted into a digital quantity D by the acquisition instrument through signal conditioning processes such as filtering, amplification and the like, and finally the digital quantity D is transmitted to computer test software. For a multi-sensor negative pressure test system, links such as a sensor, a contact/transmission resistance, a conditioning process and the like of each channel cannot be completely consistent, and therefore, the system error epsilon of each channel cannot be completely consistent. This is one of the main error sources of the multi-sensor negative pressure test system, which seriously affects the reliability and the overall accuracy of the multi-sensor negative pressure test system and needs to be solved urgently.
disclosure of Invention
In view of the above disadvantages of the prior art, the present invention aims to eliminate the system error of each channel of the multi-sensor negative pressure test system to the maximum extent, greatly improve the reliability and the overall accuracy of the negative pressure test system, and provide a normalization method for a pulse wind tunnel multi-sensor negative pressure test system.
In order to achieve the purpose, the technical scheme of the invention is as follows:
A normalization method of a pulse wind tunnel multi-sensor negative pressure test system comprises the following steps:
(1) Calibrating and tracing a standard vacuum absolute pressure sensor: the vacuum absolute pressure sensor is sent to more than two levels of metering stations with vacuum pressure calibration quality for calibration;
(2) the multi-sensor negative pressure test system is calibrated on site: calibrating the pressure values of all line sensors of the whole test system by taking the vacuum absolute pressure sensor as an intermediary for magnitude transmission, and obtaining the field sensitivity ki (i is 1, 2, … …, n) of each sensor;
(3) the actual pressure increment value Δ pi is calculated by multiplying the field sensitivity ki by the output voltage difference Δ Ui during the test.
Preferably, the method further comprises the following steps before the step (2):
(2.1) configuring a high-frequency dynamic absolute pressure sensor for each test channel, limiting the length of the pressure measuring pipe to be within 200mm, or directly installing the sensor at the near end of a pressure measuring hole of a model, thus forming a multi-sensor negative pressure test system, wherein each channel comprises a pressure sensor, a transmission line, a conditioner and an acquisition instrument and is used for a plurality of signal conversion and transmission links; the pressure sensor converts the physical pressure quantity P into a circuit analog quantity A, the circuit analog quantity A is converted into a digital quantity D by the acquisition instrument through the processes of filtering, amplifying and signal conditioning, and finally the digital quantity D is transmitted to computer test software.
preferably, the step (1) is specifically:
(1) Standard vacuum absolute pressure sensor calibration tracing source
The calibration of a vacuum absolute pressure sensor requires that the vacuum absolute pressure sensor have an accuracy of better than 0.25%, a response frequency above 500Hz, and be calibrated at least by a national secondary metering station.
Preferably, the step (2) is specifically:
(2) the multi-sensor negative pressure test system is calibrated on site:
Under the condition of field test wiring, introducing absolute vacuum with absolute error less than +/-10 < -1 > Pa into the pressure inlet end of the standard vacuum absolute pressure sensor, obtaining the system error of the standard vacuum absolute pressure sensor and the test line thereof through field zero calibration, and correcting the system error of the standard vacuum absolute pressure sensor and the test line thereof, wherein the correction refers to the translation zero clearing of the output pressure numerical values of the vacuum absolute pressure sensor and the test line thereof.
Preferably, the step (2) is specifically:
(2) the multi-sensor negative pressure test system is calibrated on site:
after the calibration of the standard vacuum absolute pressure sensor used in the field is completed, output voltage discrete point data Uij (j is 1, 2, 3, 4, 5, … …) of each sensor in the test line of each sensor is obtained by taking the output pressure value of the standard vacuum absolute pressure sensor and the test line thereof as a standard, a fitted straight line of the real-time calibration data Uij least square method of the pressure sensor in the range to be measured is obtained, and the ki value of the test line corresponding to each sensor is calculated, wherein ki is the field sensitivity of the ith sensor, namely the slope value of the corresponding fitted straight line, and P0 is the pressure variation of the standard vacuum absolute pressure sensor.
Preferably, the negative pressure test system is a pulse wind tunnel multi-channel test system with the pressure lower than the ambient atmospheric pressure.
For a sensor with linearity better than 0.25%, the linear fitting sensitivity of the sensor can be obtained by the above steps. For sensors with linearity less than 0.5%, a non-linear quadratic curve least squares fit must be used, which can make the fit residuals significantly smaller than the linear fit residuals.
For a multi-sensor negative pressure test system, the sensor, the contact/transmission resistance and the conditioning process of each channel are not completely consistent, and the system error epsilon of each channel is not completely consistent. The method can eliminate the system error.
the invention has the beneficial effects that: the normalization method can effectively eliminate the system error of each channel of the multi-sensor negative pressure test system, and can greatly improve the reliability and the overall accuracy of the negative pressure test system.
drawings
FIG. 1 is a schematic diagram of a data conversion and transmission process of a multi-sensor negative pressure test system according to the present invention;
FIG. 2 is a data conversion and transmission flow of a conventional multi-sensor negative pressure test system;
FIG. 3 is a real-time calibration data and a fitting curve of a partial pressure sensor in a range to be measured (e.g., absolute pressure of 0-1000 Pa).
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
example 1
A normalization method for a pulse wind tunnel multi-sensor negative pressure test system comprises the following three steps:
(1) calibrating and tracing a standard vacuum absolute pressure sensor: the vacuum absolute pressure sensor is sent to more than two levels of metering stations with vacuum pressure calibration quality for calibration;
(2) the multi-sensor negative pressure test system is calibrated on site: calibrating the pressure values of all line sensors of the whole test system by taking the vacuum absolute pressure sensor as an intermediary for magnitude transmission, and obtaining the field sensitivity ki (i is 1, 2, … …, n) of each sensor;
(3) the actual pressure increment value Δ pi is calculated by multiplying the field sensitivity ki by the output voltage difference Δ Ui during the test.
example 2
a normalization method of a pulse wind tunnel multi-sensor negative pressure test system comprises the following steps:
(1) standard vacuum absolute pressure sensor calibration tracing source
The vacuum absolute pressure sensor is sent to more than two levels of metering stations with vacuum pressure calibration quality for calibration; the vacuum absolute pressure sensor is required to have the precision of better than 0.25% and the response frequency of more than 500 Hz;
(2.1) configuring a high-frequency dynamic absolute pressure sensor for each test channel, limiting the length of the pressure measuring pipe to be within 200mm, or directly installing the sensor at the near end of a pressure measuring hole of a model, thus forming a multi-sensor negative pressure test system, wherein each channel comprises a pressure sensor, a transmission line, a conditioner and an acquisition instrument and is used for a plurality of signal conversion and transmission links; the pressure sensor converts the physical pressure quantity P into a circuit analog quantity A, the circuit analog quantity A is converted into a digital quantity D by the acquisition instrument through the processes of filtering, amplifying and signal conditioning, and finally the digital quantity D is transmitted to computer test software.
(2) The multi-sensor negative pressure test system is calibrated on site:
Under the condition of field test wiring, introducing absolute vacuum with absolute error less than +/-10 < -1 > Pa into the pressure inlet end of the standard vacuum absolute pressure sensor, obtaining the system error of the standard vacuum absolute pressure sensor and the test line thereof through field zero calibration, and correcting the system error of the standard vacuum absolute pressure sensor and the test line thereof, wherein the correction refers to the translation zero clearing of the output pressure numerical values of the vacuum absolute pressure sensor and the test line thereof.
Calibrating the pressure values of all line sensors of the whole test system by taking the vacuum absolute pressure sensor as an intermediary for magnitude transmission, and obtaining the field sensitivity ki (i is 1, 2, … …, n) of each sensor;
(3) The actual pressure increment value Δ pi is calculated by multiplying the field sensitivity ki by the output voltage difference Δ Ui during the test.
Example 3
A normalization method of a pulse wind tunnel multi-sensor negative pressure test system comprises the following steps:
(1) Standard vacuum absolute pressure sensor calibration tracing source
The vacuum absolute pressure sensor is sent to more than two levels of metering stations with vacuum pressure calibration quality for calibration; the vacuum absolute pressure sensor is required to have the precision of better than 0.25% and the response frequency of more than 500 Hz;
(2.1) configuring a high-frequency dynamic absolute pressure sensor for each test channel, limiting the length of the pressure measuring pipe to be within 200mm, or directly installing the sensor at the near end of a pressure measuring hole of a model, thus forming a multi-sensor negative pressure test system, wherein each channel comprises a pressure sensor, a transmission line, a conditioner and an acquisition instrument and is used for a plurality of signal conversion and transmission links; the pressure sensor converts the physical pressure quantity P into a circuit analog quantity A, the circuit analog quantity A is converted into a digital quantity D by the acquisition instrument through the processes of filtering, amplifying and signal conditioning, and finally the digital quantity D is transmitted to computer test software.
(2) The multi-sensor negative pressure test system is calibrated on site:
Under the condition of field test wiring, introducing absolute vacuum with absolute error less than +/-10 < -1 > Pa into the pressure inlet end of the standard vacuum absolute pressure sensor, obtaining the system error of the standard vacuum absolute pressure sensor and the test line thereof through field zero calibration, and correcting the system error of the standard vacuum absolute pressure sensor and the test line thereof, wherein the correction refers to the translation zero clearing of the output pressure numerical values of the vacuum absolute pressure sensor and the test line thereof.
The calibration result of the on-site standard vacuum absolute pressure sensor SJ-1 from a certain secondary metering station is shown in Table 1, and it can be seen that the original error of the calibration value is within + 1%, the other distribution deviations are consistent except for a slightly larger deviation caused by converting the standard sensor at 3000Pa, and the average deviation value is about 33Pa, so that the linear translation correction can be performed. After correction, the error of the corrected value is within +/-0.25%, and the corrected value is consistent with the nominal precision value. The sensor meets the precision requirement of a field standard vacuum absolute pressure sensor.
TABLE 1 calibration results of a standard vacuum absolute pressure sensor SJ-1 in situ
After the calibration of the standard vacuum absolute pressure sensor used in the field is finished, obtaining output voltage discrete point data Uij (j is 1, 2, 3, 4, 5, … …) of each sensor in the test line thereof by taking the output pressure value of the standard vacuum absolute pressure sensor and the test line thereof as a standard, obtaining a fitted straight line of real-time calibration data Uij least square method of the pressure sensor in a range to be measured, and calculating a ki value of the test line corresponding to each sensor, wherein ki is the field sensitivity of the ith sensor, namely the slope value of the corresponding fitted straight line, and P0 is the pressure variation of the standard vacuum absolute pressure sensor;
(3) the actual pressure increment value Δ pi is calculated by multiplying the field sensitivity ki by the output voltage difference Δ Ui during the test.
The real-time calibration data and the fitting curve of a part of pressure sensors in a range to be measured (such as absolute pressure of 0-1000 Pa) are shown in FIG. 3. For sensors with linearity less than 0.5%, a non-linear quadratic curve least squares fit must be used, which can make the fit residuals significantly smaller than the linear fit residuals. Therefore, all sensors and all test lines are normalized to the field standard vacuum absolute pressure sensor and the test line thereof, and the system error caused by individual difference and system change of each sensor and the test line thereof is eliminated to the maximum extent.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (6)
1. A normalization method for a pulse wind tunnel multi-sensor negative pressure test system is characterized by comprising the following steps:
(1) calibrating and tracing a standard vacuum absolute pressure sensor: the vacuum absolute pressure sensor is sent to more than two levels of metering stations with vacuum pressure calibration quality for calibration;
(2) The multi-sensor negative pressure test system is calibrated on site: calibrating the pressure values of all line sensors of the whole test system by taking the vacuum absolute pressure sensor as an intermediary for magnitude transmission, and obtaining the field sensitivity ki (i is 1, 2, … …, n) of each sensor;
(3) The actual pressure increment value Δ pi is calculated by multiplying the field sensitivity ki by the output voltage difference Δ Ui during the test.
2. the method for normalizing the negative pressure test system of the multiple sensors in the pulse wind tunnel according to claim 1, wherein the method comprises the following steps: the method also comprises the following steps before the step (2):
(2.1) configuring a high-frequency dynamic absolute pressure sensor for each test channel, limiting the length of the pressure measuring pipe to be within 200mm, or directly installing the sensor at the near end of a pressure measuring hole of a model, thus forming a multi-sensor negative pressure test system, wherein each channel comprises a pressure sensor, a transmission line, a conditioner and an acquisition instrument and is used for a plurality of signal conversion and transmission links; the pressure sensor converts the physical pressure quantity P into a circuit analog quantity A, the circuit analog quantity A is converted into a digital quantity D by the acquisition instrument through the processes of filtering, amplifying and signal conditioning, and finally the digital quantity D is transmitted to computer test software.
3. the method for normalizing the negative pressure test system of the multiple sensors in the pulse wind tunnel according to claim 1, wherein the method comprises the following steps: the step (1) is specifically as follows:
(1) standard vacuum absolute pressure sensor calibration tracing source
The calibration of a vacuum absolute pressure sensor requires that the vacuum absolute pressure sensor have an accuracy of better than 0.25%, a response frequency above 500Hz, and be calibrated at least by a national secondary metering station.
4. The method for normalizing the negative pressure test system of the multiple sensors in the pulse wind tunnel according to claim 1, wherein the method comprises the following steps: the step (2) is specifically as follows:
(2) the multi-sensor negative pressure test system is calibrated on site:
under the condition of field test wiring, introducing absolute vacuum with absolute error less than +/-10 < -1 > Pa into the pressure inlet end of the standard vacuum absolute pressure sensor, obtaining the system error of the standard vacuum absolute pressure sensor and the test line thereof through field zero calibration, and correcting the system error of the standard vacuum absolute pressure sensor and the test line thereof, wherein the correction refers to the translation zero clearing of the output pressure numerical values of the vacuum absolute pressure sensor and the test line thereof.
5. the method for normalizing the negative pressure test system of the multiple sensors in the pulse wind tunnel according to claim 1, wherein the method comprises the following steps: the step (2) is specifically as follows:
(2) The multi-sensor negative pressure test system is calibrated on site:
after the calibration of the standard vacuum absolute pressure sensor used in the field is completed, output voltage discrete point data Uij (j is 1, 2, 3, 4, 5, … …) of each sensor in the test line of each sensor is obtained by taking the output pressure value of the standard vacuum absolute pressure sensor and the test line thereof as a standard, a fitted straight line of the real-time calibration data Uij least square method of the pressure sensor in the range to be measured is obtained, and the ki value of the test line corresponding to each sensor is calculated, wherein ki is the field sensitivity of the ith sensor, namely the slope value of the corresponding fitted straight line, and P0 is the pressure variation of the standard vacuum absolute pressure sensor.
6. The method for normalizing the negative pressure test system of the multiple sensors in the pulse wind tunnel according to claim 1, wherein the method comprises the following steps: the negative pressure test system refers to a pulse wind tunnel multi-channel test system with the pressure lower than the atmospheric pressure of the environment.
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