CN112484906A - Gas pressure optical measurement temperature compensation method - Google Patents
Gas pressure optical measurement temperature compensation method Download PDFInfo
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- CN112484906A CN112484906A CN202011422516.7A CN202011422516A CN112484906A CN 112484906 A CN112484906 A CN 112484906A CN 202011422516 A CN202011422516 A CN 202011422516A CN 112484906 A CN112484906 A CN 112484906A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/04—Means for compensating for effects of changes of temperature, i.e. other than electric compensation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
- G01L11/02—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means
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Abstract
The invention relates to a temperature compensation method for optical measurement of gas pressure, and belongs to the technical field of metering test. The invention utilizes a double-spectrum method in the absorption spectrum method to measure the accurate gas temperature value in real time, and realizes the temperature correction of the pressure measurement in a gas pressure measurement model with an optical refractivity method. The invention can compensate the influence of temperature change on the measurement result in the gas pressure optical measurement in real time and improve the measurement precision of pressure.
Description
Technical Field
The invention relates to a temperature compensation method for optical measurement of gas pressure, and belongs to the technical field of metering test.
Background
Pressure is one of important parameters for mechanical measurement and testing, and is widely applied in the fields of aviation, aerospace, nuclear industry, ships, weapons and the like. In the process of testing the national defense industry, the accuracy of the pressure value directly influences the safety and the development of various fields of the national defense industry. By utilizing the advantages of high precision, high resolution, high dynamic and the like of optical measurement, the established optical pressure measurement technology is becoming a new hot spot and trend in the pressure measurement field, and important technical support is provided for realizing high-precision pressure test, high-precision pressure standard, on-site self-calibration pressure test and on-site standard in the future. The currently common optical pressure measurement method is mainly based on two methods, namely a refractive index method and an absorption spectrum method, pressure measurement results of the two methods are influenced by gas temperature changes, and how to realize effective compensation of the temperature influence is a prominent problem in the current gas pressure optical measurement.
Disclosure of Invention
The invention aims to provide a temperature compensation method in gas pressure optical measurement, which is used for realizing gas pressure optical high-precision measurement or establishing a high-precision pressure standard in a variable-temperature environment.
The purpose of the invention is realized by the following technical scheme:
a gas pressure optical measurement temperature compensation method comprises the following steps:
measuring a gas refractive index change value by using a refractive index method, and establishing the relationship among the gas refractive index, the pressure and the temperature by using a gas state equation as follows:
p＝ρRT[1+Bρ+Cρ2+Dρ3+...]
in the formula: p is gas pressure, R is an ideal gas constant, T is temperature, B, C and D are first, second and third density Viry coefficients respectively, rho is medium density, and the calculation formula is as follows:
in the formula: n is the refractive index of the gas, Aε，bεThe first and second dielectric Viry coefficients, respectively.
Step two, measuring the temperature value of the measured gas by using a double-spectral-line method in the absorption spectroscopy:
in the formula: sv1(T0) And Sv2(T0) Is composed ofReference temperature T0The intensity of the two measured absorption lines at 296K; h is Planck constant, c is speed of light, k is Boltzmann constant, E ″)1、E″2Low level energy, R, of transitions of two absorption lines, respectivelypIs the ratio of the intensities of the two absorption lines.
Step three, substituting the measured temperature value into a relation model obtained by a refractive index method, and calculating a pressure value;
advantageous effects
The invention relates to a temperature compensation method in gas optical pressure measurement, which utilizes a double-spectrum method in an absorption spectrum method to measure an accurate gas temperature value in real time and realizes temperature correction of pressure measurement in a gas pressure measurement model with an optical refractivity method. The invention can compensate the influence of temperature change on the measurement result in the gas pressure optical measurement in real time and improve the measurement precision of pressure.
Drawings
FIG. 1 is a schematic flow chart of the method of the present invention.
Detailed Description
The invention will be further described in detail with reference to the accompanying fig. 1 and examples. The present embodiment is based on the technical solution of the present invention and provides a specific implementation manner, but the scope of the present invention is not limited to the following embodiments.
The atmospheric data sensing system is used as an important airborne device of the current air vehicle, and is widely applied to important fields of unmanned aerial vehicles, fighters and the like at home and abroad. The atmospheric data sensor system is mainly used for accurately determining the atmospheric data such as the flying height, the airspeed meter, the Mach number and the like of the aircraft in real time in the whole flying process, the parameters are important information for controlling the flying attitude of the aircraft in the air, the parameters are essential information for maintaining the normal operation of the aircraft and the systems such as automatic control, navigation, fire control, air control, alarm and the like of the engine, and the atmospheric data sensor system has important significance for the flight safety. The aircraft measures the full pressure and static pressure of the altitude of the aircraft through a pressure sensor arranged in an airspeed tube near the aircraft nose, and the important data such as the altitude, the Mach number, the lifting speed, the speed and the like required in real time during flight are calculated according to the measured full pressure and static pressure. Therefore, the measurement accuracy of the pressure sensor in the air data sensing system directly influences the accuracy of other air and flight parameters, and influences the evaluation of the whole flight state.
At present, with the continuous improvement of the performance requirements of aircrafts such as unmanned planes, fighters and the like, the measurement accuracy requirements of atmospheric data sensor systems, particularly pressure sensors, are also continuously improved. The main factors influencing the further improvement of the measurement accuracy of the pressure measurement of the atmospheric data system at present are the influence of field measurement environments such as temperature and the like. Because the calibration mode of the pressure sensor of the prior aircraft airspeed head is periodically removed, calibration is carried out in a laboratory environment, and no technology and means for field calibration are provided, the temperature change of the pressure measurement position in the flight process of the aircraft inevitably affects the accuracy of pressure measurement, and even finally affects the accurate judgment of the flight state of the aircraft.
The pressure measurement technology is developed by utilizing an optical means, the pressure parameters can be directly traced to the quantum, and the pressure measurement with higher precision of field calibration and self calibration is realized. The embodiment provides an effective and feasible temperature compensation method in optical pressure measurement, can eliminate the influence caused by temperature change in optical pressure measurement, is applied to field pressure measurement of an atmospheric data system, and solves the problem that the measurement accuracy of a pressure sensor of the existing atmospheric data test system is difficult to improve. The detailed measurement procedure analysis is as follows:
the method comprises the following steps: and establishing a gas pressure measurement model based on a refractive index method by using an optical refractive index pressure measurement method.
According to the theory of electromagnetic wave propagation in space, the refractive index of gas has the following relationship with the relative permeability and dielectric constant (i.e., relative conductivity) of gas
n2＝εrμr (1)
In the formula:n is the refractive index of the gas to be measured, epsilonrIs a relative dielectric constant, murIs the relative permeability, mu in most casesr1, therefore: n is2＝εr。
According to the Clausius-Mossotti equation and the Lorentz-Lorenz equation, the relative permittivity and the relative permeability of the nonpolar gas can be respectively expanded into the form of Viley equation according to the density:
where ρ is the density of the medium, Aε，bεAnd cεFirst, second and third dielectric virial coefficients, respectively. Substituting the relational formula of the refractive index and the electromechanical constant and neglecting high-order terms, the following are:
further advancing to:
bερ2+Aερ-(n2-1)/(n2+2)＝0 (4)
solving to obtain:
according to the ideal gas state equation, the following steps are provided:
p＝ρRT[1+Bρ+Cρ2+Dρ3+...] (6)
where p is the measured gas pressure, R is the ideal gas constant, T is the temperature, and B, C, and D are the first, second, and third density Viry coefficients, respectively. And (5) bringing the density formula (5) into formula (6), and establishing a relation model between the pressure p of the gas, the temperature T and the refractive index n.
Step two: and measuring the temperature value of the gas to be measured by using a double-spectral-line method in the absorption spectroscopy.
After the laser passes through the gas medium, the light intensity changes according to the Beer-Lambert law, and the following conditions are provided:
in the formula I0Is the intensity of the laser beam, ItIs the detector's received light intensity, p is the measured gas pressure, C is the gas volume ratio, S (T) is the line intensity of the absorption spectrum, which is a function of Kelvin temperature T, L is the effective length of the gas cavity, and Φ (v) is a linear function.
In the laser absorption path L, the absorption rate A is integratediComprises the following steps:
Ai＝∫S(T)Φ(v)pCLdv＝S(T)pCL (8)
when the gas temperature is measured by adopting a double-line temperature measurement method, two gas absorption lines are obtained by scanning the same gas in the same absorption path for one time, parameters such as gas volume ratio, pressure intensity and the like can be eliminated by operation, and the ratio R of the intensities of the two absorption spectral lines is obtainedpComprises the following steps:
the average temperature on the optical path can then be found to be
And step three, combining the formulas (6) and (10), namely substituting the measured temperature value into a model obtained by a refractive index method, and calculating an accurate pressure value after temperature compensation.
Through the measurement process and the analysis and calculation, the refractive index method and the absorption spectrum method in the optical pressure measurement are combined, the temperature compensation in the high-precision pressure optical measurement is realized, and a feasible scheme can be provided for the field pressure accurate calibration and measurement of an atmospheric data system.
The above detailed description is intended to illustrate the objects, aspects and advantages of the present invention, and it should be understood that the above detailed description is only exemplary of the present invention and is not intended to limit the scope of the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (1)
1. A gas pressure optical measurement temperature compensation method is characterized in that: the method comprises the following steps:
measuring a gas refractive index change value by using a refractive index method, and establishing the relationship among the gas refractive index, the pressure and the temperature by using a gas state equation as follows:
p＝ρRT[1+Bρ+Cρ2+Dρ3+...]
in the formula: p is gas pressure, R is an ideal gas constant, T is temperature, B, C and D are first, second and third density Viry coefficients respectively, rho is medium density, and the calculation formula is as follows:
in the formula: n is the refractive index of the gas, Aε，bεFirst and second dielectric Viry coefficients, respectively;
step two, measuring the temperature value of the measured gas by using a double-spectral-line method in the absorption spectroscopy:
in the formula: sv1(T0) And Sv2(T0) Is a reference temperature T0The intensity of the two measured absorption lines at 296K; h is PlanckConstant, c is the speed of light, k is the Boltzmann constant, E "1、E"2Low level energy, R, of transitions of two absorption lines, respectivelypIs the ratio of the intensities of the two absorption lines;
step three, substituting the measured temperature value into a relation model obtained by a refractive index method, and calculating a pressure value;
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109459411A (en) * | 2018-12-29 | 2019-03-12 | 云南电网有限责任公司电力科学研究院 | A kind of detection platform for spectral type fibre optical sensor |
| CN109580546A (en) * | 2018-12-19 | 2019-04-05 | 天津大学 | A kind of Fabry-perot optical fiber gas refracting index and temperature sensor and system, measurement method |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109580546A (en) * | 2018-12-19 | 2019-04-05 | 天津大学 | A kind of Fabry-perot optical fiber gas refracting index and temperature sensor and system, measurement method |
| CN109459411A (en) * | 2018-12-29 | 2019-03-12 | 云南电网有限责任公司电力科学研究院 | A kind of detection platform for spectral type fibre optical sensor |
Non-Patent Citations (2)
| Title |
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| 孙冬远 等: "基于激光双吸收谱线的氨气温度测量研究", 《激光与红外》 * |
| 许玉蓉 等: "基于气体折射率方法的真空计量", 《物理学报》 * |
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