CN114323548B - Calibration method for pressure-sensitive paint coating suitable for different reference states - Google Patents
Calibration method for pressure-sensitive paint coating suitable for different reference states Download PDFInfo
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Abstract
The invention discloses a calibration method of a pressure-sensitive paint coating suitable for different reference states, which comprises the following steps of firstly, before a wind tunnel test, obtaining a pre-test calibration fitting relational expression and a fitting curved surface of the pressure-sensitive paint coating under the conditions that atmospheric pressure and ambient temperature at the calibration moment are used as reference pressure and temperature based on parameter setting of a calibration box and paint calibration software; and secondly, during the wind tunnel test, reversely calculating the coating light intensity ratio under the real reference condition based on the pre-test calibration fitting relational expression by actually measuring the atmospheric pressure and the ambient temperature in the tunnel, so as to obtain the post-test calibration fitting relational expression and the fitting curved surface of the pressure-sensitive paint coating under the condition that the atmospheric pressure and the ambient temperature in the tunnel during the wind tunnel test are taken as the reference conditions. The invention provides a pressure-sensitive paint calibration method suitable for different reference states, which is used for optimizing the existing pressure-sensitive paint calibration method and simplifying the preparation processes before a pressure-sensitive paint calibration test and a wind tunnel test, thereby improving the pressure-sensitive paint calibration precision.
Description
Technical Field
The invention relates to the technical field of wind tunnel tests. More particularly, the present invention relates to a method for calibrating pressure sensitive paint coatings suitable for use in different reference conditions.
Background
The Pressure Sensitive Paint (Pressure Sensitive Paint-PSP) technology is an optical Pressure measurement test technology, which is a measuring method that utilizes photoluminescence characteristics of high molecular organic matters and 'oxygen quenching' effect of deactivating excited probe molecules by oxygen molecules, irradiates a tested object surface fully covered with probe molecule Pressure Sensitive Paint with an excitation light source with proper wavelength, captures a coating surface gray level image by a light intensity acquisition device, and obtains a tested object surface Pressure distribution map through image processing and gray level and Pressure conversion. The technology measures the continuous change pressure map of the whole domain of the model surface in a non-contact mode, can more intuitively, comprehensively and accurately reflect the pressure structure condition of the tested object surface in the air flow, makes up and avoids the inherent defects and shortcomings of the traditional pressure measurement method taking a pressure sensor as a measurement original, and embodies the irreplaceable unique advantages. In recent ten years, the pressure sensitive paint pressure measuring technology based on the light intensity method is rapidly developed in various scientific research institutions and colleges at home and abroad, and the pressure sensitive paint pressure measuring technology enters the engineering application stage at present and becomes a necessary test means for various production type wind tunnels at home and abroad.
The schematic diagram of a light intensity method PSP wind tunnel measurement system is shown in FIG. 1. The specific test flow of the PSP test technology is as follows: firstly, before a wind tunnel test, obtaining a calibration relational expression (Stern-Volmer relational expression) of pressure-sensitive paint light intensity and pressure through a pressure-sensitive paint calibration test; in the wind tunnel test, the surface of an object to be tested containing the probe molecule pressure sensitive paint is fully irradiated by exciting light with proper wavelength, and a CCD camera acquires a light intensity image of the surface coating of the model and transmits the light intensity image to a computer; and thirdly, after the wind tunnel test, converting the light intensity image into a pressure image by using image post-processing software and a Stern-Volmer relational expression calibrated before the test, thereby obtaining a model surface pressure map.
Compared with the traditional PSI pressure measuring method, the PSP pressure measuring technology has the unique advantages of non-contact flow field non-disturbance, high spatial resolution and the like, but the number of error sources involved in the test technology is large, and the accumulated superposition of errors can bring great influence on the uncertainty of the test result, so that the pressure measurement accuracy of the test technology is influenced. The PSP technique generally includes a number of error sources such as model deformation motion due to loading, reference pressure measurement error, photodegradation and impurity deposition of paint, instability of excitation light, spectral leakage of filter, camera noise, coating convection field interference, and paint calibration error. The quantitative relation between the luminous intensity of the coating and the surface pressure of the model is obtained through a calibration experiment, and therefore, the coating calibration error is one of important error sources in the pressure-sensitive paint test technology. The method for improving the coating calibration accuracy starts from two aspects, on one hand, hardware equipment with good performance and applicability is selected, such as a light source with high output light intensity stability, a filter with small spectrum leakage amount, temperature and pressure control equipment with good stability and high accuracy, a calibration box with good sealing performance and the like, and on the other hand, the calibration method needs to be researched systematically so as to optimize the calibration technical details. The technical details involved in the paint calibration process are many, and the final calibration accuracy may be affected to different degrees by adjusting the light intensity of the collected images, the number of average images, selecting image-taking regions, selecting filtering, adjusting the image definition, selecting the analog-to-digital conversion digits and the like. At present, a high-stability ultraviolet source and a low-noise scientific CCD camera are selected as pressure-sensitive paint calibration hardware equipment used in engineering, the pressure tightness of a calibration box is good, the pressure and temperature are controlled accurately, in addition, a large amount of fine researches are carried out on a paint calibration method and details, a set of scientific and feasible paint calibration method and standard are formed, and the calibration accuracy of the whole pressure-sensitive paint is high.
In the calibration of the pressure-sensitive paint, a calibration relation between the ratio of the light intensity of the sample coating under different pressures and temperatures and the light intensity of the sample coating under the conditions of pressure and temperature determined in advance (the state is called as a reference state) and the pressure and temperature of the sample coating at the station needs to be finally obtained, the pressure and the temperature of the reference state are set to be the atmospheric pressure and the ambient temperature during the actual wind tunnel test, and if the pressure and the temperature of the reference state are set inaccurately, a system error is brought to the final pressure result conversion. The pressure-sensitive calibration test is generally completed before the wind tunnel test, the reference pressure and temperature of the general flow of the current pressure-sensitive paint calibration test are set as the atmospheric pressure and the ambient temperature during the calibration test, and the atmospheric pressure and the ambient temperature during the calibration test are considered to be generally not completely consistent with those during the subsequent wind tunnel test, so that a calibration error is introduced, and finally, a pressure measurement error of the pressure-sensitive paint test is caused.
Taking the reference pressure as an example, the atmospheric pressure is related to the ambient altitude, temperature and humidity. As altitude increases, the air pressure decreases accordingly, in the three kilometer range, by 133 pa for every 12 meters rise. The altitude of each place is greatly different in China, for example, the altitude of Beijing is 31 meters, the atmospheric pressure is about 99.8 kilopascals, the altitude of Shanghai is 4.5 meters, the atmospheric pressure is about 100.5 kilopascals, Kunming is on a plateau, the altitude is about 1891 meters, the atmospheric pressure is about 80.8 kilopascals, and the difference of the atmospheric pressure of the three is 19.7 kilopascals at most. Considering that the measurement precision of the conventional pressure-sensitive paint technology is within 1 kilopascal, the pressure-sensitive paint calibration test result carried out in a certain area cannot be applied to the pressure-sensitive paint wind tunnel test in other places, and the paint calibration test must be carried out again in the local place. Meanwhile, the temperature also has great influence on the atmospheric pressure, and in one year, the temperature is low in winter, the temperature is high in summer, and the air pressure in winter is higher than the air pressure in summer. Even in the same day, the air pressure still has great change, and the atmospheric pressure change range that the temperature arouses has 400 pa or so, and for the pressure sensitive paint technique that measurement accuracy is within 1 kilopascal, the coating calibration error that the reference pressure change arouses within a day is also ignorable.
In a word, the existing calibration method for the pressure-sensitive paint coating cannot accurately set the pressure and the temperature of the reference state, the atmospheric pressure and the ambient temperature in different regions and different seasons in the same region are greatly different, the setting errors of the pressure and the temperature of the reference state in a calibration test and a wind tunnel test are large, so that the calibration results in different regions and seasons cannot be adopted at all, and the calibration must be carried out again in real time locally. Meanwhile, even if the calibration test and the wind tunnel test are in the same region and season, the reference state pressure and temperature of the calibration test completed before the test still have obvious deviation from those of the wind tunnel test, and the final measurement deviation is still not negligible. In order to simplify the preparation process before the pressure-sensitive paint calibration test and the wind tunnel test, the existing pressure-sensitive paint calibration method and process need to be optimized, and the applicability and the calibration precision of the pressure-sensitive paint calibration result are improved.
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 method for calibrating a pressure-sensitive paint coating adapted for use in different reference states, comprising:
Firstly, before a wind tunnel test, obtaining a pre-test calibration fitting relational expression and a fitting curved surface of the pressure-sensitive paint coating under the conditions that atmospheric pressure and ambient temperature at the calibration moment are used as reference pressure and temperature based on parameter setting of a calibration box and coating calibration software;
and step two, during wind tunnel test, reversely calculating the coating light intensity ratio under the real reference condition based on the pre-test calibration fitting relational expression by actually measuring the atmospheric pressure and the ambient temperature in the tunnel, so as to obtain the post-test calibration fitting relational expression and the fitting curved surface of the pressure-sensitive paint coating under the condition that the atmospheric pressure and the ambient temperature in the tunnel during the wind tunnel test are used as the reference conditions.
Preferably, in the first step, the obtaining manner of the pre-test calibration fitting relation is configured to include:
s10, preparing a test sample with pressure-sensitive paint, and arranging the test sample in a calibration box;
s11, obtaining coating light intensity sequence images under each station and coating surface light intensity images under a reference state based on hardware in the calibration box and corresponding coating calibration software;
s12, obtaining a light intensity ratio sequence under each station based on the processing of the light intensity images of the coating surface under the reference state and the light intensity sequence images of the coating under each station;
And S13, fitting the pressure value sequence, the temperature sequence and the light intensity ratio sequence set by each station to obtain a pre-test calibration fitting relational expression of the pressure, the temperature and the light intensity ratio and a fitting curved surface.
Preferably, in S10, the preparing step of the test piece is configured to include:
s101, polishing a sample wafer, cleaning the surface of the sample wafer by using alcohol or acetone, and volatilizing a surface cleaning solvent in a clean environment until the surface of the sample wafer is dried;
s102, stirring the pressure-sensitive paint primer and the acetone until the pressure-sensitive paint primer and the acetone are completely and uniformly dispersed, and uniformly spraying the pressure-sensitive paint primer to the surface of the sample wafer by using a spray gun;
s103, placing the sample wafer sprayed with the pressure-sensitive paint primer in an oven for baking until the primer coating solvent is completely volatilized, and curing the primer;
s104, polishing the sample wafer primer by using abrasive paper, cleaning the surface of the primer by using alcohol, and volatilizing a surface cleaning solvent in a clean environment until the surface of the sample wafer primer is dried;
s105, stirring the pressure-sensitive paint finish and the acetone until the pressure-sensitive paint finish and the acetone are completely and uniformly dispersed, and uniformly spraying the pressure-sensitive paint finish to the surface of the sample primer by using a spray gun;
s106, placing the sample wafer coated with the pressure-sensitive paint finish in an oven for baking until the solvent of the finish coating is completely volatilized, and curing the finish, wherein the surface of the cured finish is not polished;
S107, smearing heat-conducting silica gel on the surface of the sample without the pressure-sensitive paint, adhering and fixing the sample on a base of the calibration box, closing and sealing the calibration box, and ensuring that the calibration box is good in sealing.
Preferably, in S11, the method for acquiring the coating light intensity sequence images at each station includes:
s110, setting pressures and temperatures under different stations through coating calibration software, and adjusting the pressures and temperatures in the calibration box based on a pressure controller and a temperature controller in the calibration box so as to enable the pressures and temperatures in the calibration box to be matched with the pressures and temperatures set by each station;
s111, turning on a light source in a calibration box to irradiate the pressure-sensitive coating on the surface of the sample wafer, and collecting a light intensity image on the surface of the sample wafer coating under each station through a camera to obtain a coating light intensity sequence image corresponding to each station;
the acquisition mode of the light intensity image of the coating surface in the reference state comprises the following steps:
s112, setting reference state pressure and temperature according to atmospheric pressure and ambient temperature during a calibration test, and regulating and controlling the pressure and temperature in the calibration box through a pressure controller and a temperature controller so as to enable the pressure and temperature in the calibration box to be matched with the set reference state pressure and temperature;
S113, turning on a light source to irradiate the pressure-sensitive coating on the surface of the sample wafer, and acquiring a light intensity image of the surface of the sample wafer coating in a reference state through a camera.
Preferably, in S12, the obtaining manner of the light intensity ratio sequence is configured to include:
s120, selecting a partial area in the image as a calibration area, and averaging the image light intensity in the reference state and the light intensity image under each station in the calibration area to obtain the reference light intensity of the image light intensity in the reference state in the calibration area and the light intensity of the image light intensity sequence under each station in the calibration area;
and S121, comparing the reference light intensity with the light intensity of each station to obtain a light intensity ratio sequence under each station.
Preferably, in S13, the pre-trial calibration fitting relation is expressed as:
wherein, P is the pressure under each station,
the ratio of the light intensity of each station image to the light intensity of the reference image, T is the temperature under each station,
and n is the fitting order of the fitting relation.
Preferably, in the second step, during the wind tunnel test, the real-time atmospheric pressure P 'and the ambient temperature T' in the wind tunnel test section are measured by a pressure sensor and a temperature sensor arranged in the wind tunnel, and the P 'and the T' are substituted into the pre-test calibration fitting relation to obtain the ratio of the coating light intensity under the atmospheric pressure and the ambient temperature during the test to the coating light intensity under the atmospheric pressure and the ambient temperature during the pre-test calibration, and further calculate the coating light intensity under the atmospheric pressure and the ambient temperature during the test;
The method comprises the following steps of taking coating light intensity under atmospheric pressure and ambient temperature during testing as reference image light intensity, obtaining light intensity value under different stations obtained during calibration before testing and reference image light intensity to be compared again, obtaining station light intensity ratio sequences taking the atmospheric pressure and the ambient temperature under the actual wind tunnel test state as reference conditions, and re-fitting pressure value sequences, the light intensity ratio sequences and the temperature sequences set by the stations to obtain a calibration fitting relational expression after testing and a fitting curved surface of the pressure-sensitive paint coating, wherein the calibration fitting relational expression after testing is a polynomial and can be expressed as follows:
wherein, P is the pressure under each station,
the ratio of the light intensity of the image of each station to the light intensity of the reference image, T is the temperature under each station,
and n is the fitting order of the fitting relation for the calibration coefficient to be solved.
The invention at least comprises the following beneficial effects: firstly, the method actually measures the atmospheric pressure and the ambient temperature in the tunnel during the wind tunnel test, and reversely calculates the coating light intensity value under the real reference condition by using the pressure-sensitive paint calibration relational expression obtained before the test, thereby obtaining the accurate pressure-sensitive paint calibration relation taking the atmospheric pressure and the ambient temperature in the tunnel as the reference condition during the wind tunnel test, reducing the calibration error and improving the pressure measurement accuracy of the pressure-sensitive paint technology.
Secondly, aiming at certain pressure-sensitive paint and measuring equipment, the method can meet the use requirements of pressure-sensitive paint wind tunnel tests in different regions and seasons by only carrying out coating calibration once, so that the method optimizes the conventional pressure-sensitive paint calibration method, simplifies the pressure-sensitive paint calibration test and the preparation process before the wind tunnel test, improves the applicability and the calibration precision of the pressure-sensitive paint calibration result, and has higher popularization and application values.
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 PSP wind tunnel measurement system in the prior art;
FIG. 2 shows the internal structure of the calibration tank according to the present invention;
FIG. 3 is a schematic diagram of a calibration apparatus according to embodiment 1 of the present invention;
FIG. 4 is a flow chart of a method for calibrating a pressure sensitive paint coating suitable for use in different reference states according to the present invention;
FIG. 5 is a calibration curve obtained by the method of the present invention, using the test parameters in example 1 as an example;
FIG. 6 is a calibration curve obtained by a conventional PSP calibration method, taking the test parameters in example 1 as an example;
FIG. 7 is a surface pressure coefficient map of the model of example 1 obtained by the method provided by the present invention;
FIG. 8 is a comparison of the measurement accuracy of the pressure coefficient obtained in example 1 using the calibration method provided by the present invention and a conventional calibration method;
wherein, in FIG. 1, 1-paint model, 2-marker points, 3-paint model surface after partial enlargement, 4-substrate, 5-polymer layer, 6-pressure sensitive probes in polymer, 7-computer, 8-CCD camera, 9-camera filter, 10-excitation light;
in FIG. 2, 11-heat sink, 12-heater, 13 is a copper plate made of aluminum, and 14 is a pressure sensitive paint layer;
in fig. 3, 15-switching valve one, 16-CPC3, 17-relay one, 18-relay two, 19-switching valve two.
Detailed Description
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.
The invention aims to solve the problem of providing a pressure-sensitive paint calibration method suitable for different reference states, which can obtain accurate pressure-sensitive paint calibration relation under different reference pressure conditions by utilizing a paint calibration test once in the calibration process so as to optimize the conventional pressure-sensitive paint calibration method, simplify the preparation processes before the pressure-sensitive paint calibration test and the wind tunnel test, improve the preparation efficiency before the pressure-sensitive paint test, and further improve the applicability and the calibration precision of a pressure-sensitive paint calibration result.
The technical problem is solved by the following technical scheme: a method for calibrating a pressure-sensitive paint coating suitable for use in different reference states, comprising the steps of:
s1, polishing the sample wafer, cleaning the surface of the sample wafer by using alcohol or acetone, volatilizing the surface cleaning solvent in a clean environment until the surface of the sample wafer is dried, and in the step S1, using an aluminum sample wafer with the thickness of 2 mm in order to avoid processing deformation and take account of rapid heat conduction and temperature balance;
s2, stirring the pressure-sensitive paint primer and the solvent until the pressure-sensitive paint primer and the solvent are completely and uniformly dispersed, uniformly spraying the pressure-sensitive paint primer on the surface of the sample wafer by using a spray gun, and in the step S2, uniformly mixing the pressure-sensitive paint primer and the solvent by using an automatic stirrer, wherein the thickness of the primer is 20 microns;
s3, placing the sample wafer sprayed with the pressure-sensitive paint primer into a baking oven for baking until the primer coating solvent is completely volatilized, curing the primer, setting the baking temperature of the baking oven in the step S3 to be 90 ℃, and setting the baking time to be 5 hours;
s4, grinding the priming paint of the sample wafer by using abrasive paper, cleaning the surface of the priming paint by using alcohol, volatilizing a surface cleaning solvent in a clean environment until the surface of the priming paint of the sample wafer is dried, and grinding the surface of the priming paint by using 1500-mesh abrasive paper in the step S4 until the surface roughness is less than 0.8;
S5, stirring the pressure-sensitive paint finish and the solvent until the two are completely and uniformly dispersed, uniformly spraying the pressure-sensitive paint finish on the surface of the sample piece primer by using a spray gun, and in the step S5, uniformly mixing the pressure-sensitive paint finish and the solvent by using an automatic stirrer, wherein the thickness of the finish is 20 micrometers;
s6, placing the sample wafer sprayed with the pressure-sensitive paint finish into a baking oven for baking until the solvent of the finish coating is completely volatilized, curing the finish, and not polishing the surface of the cured finish, wherein in the step S6, the baking temperature of the baking oven is 65 ℃ and the baking time is 5 hours;
and S7, smearing heat-conducting silica gel on one surface of the sample without the pressure-sensitive paint, adhering the sample to a base of a calibration box, closing and sealing the calibration box to ensure that the calibration box is well sealed, wherein in the step S7, the internal structure of the calibration box is as shown in figure 2, the calibration box is a copper base, the other end of the base is fixed with a thermoelectric heater, and a gap between the base and the heater is filled with the heat-conducting silica gel. The semiconductor temperature controller is utilized to change the current direction input by the thermoelectric heater, so that the brass plate can be heated or cooled, the temperature of the sample wafer is further changed, and the adjustment of the temperature of the sample wafer is realized. The temperature control range of the calibration box is-10 ℃ to 100 ℃, and the control error is as follows: plus or minus 0.5 ℃. Wherein, the function of heat conduction silicone oil and brass plate is to make the heater heat the sample wafer evenly.
S8, starting coating calibration software, setting pressures and temperatures of different stations, regulating and controlling the pressure and the temperature in the calibration box to the set pressure and temperature of each station through a pressure controller and a temperature controller, starting a light source to irradiate the pressure-sensitive coating on the surface of the sample wafer, and acquiring the surface light intensity image of the coating of the sample wafer by adopting a camera under each station to obtain the coating light intensity sequence image under each station;
further, in the step S8, the pressure controller is a high-precision digital pressure controller, the pressure control range is 0 to 500kPa, and the control precision is 0.05% FS. The light source is an ultraviolet light source with a spectrum peak value of 405 nanometers, the continuous excitation mode and the pulse excitation mode are provided, and the irradiation intensity, the pulse duty ratio, the period and the pulse number can be automatically adjusted through light source control software. The camera is a scientific grade color CCD, the camera is provided with a backboard for refrigeration, the resolution is at least 1600 multiplied by 800, and the bit depth is more than 8 bits;
s9, setting reference state pressure and temperature according to atmospheric pressure and environmental temperature during calibration test, regulating and controlling the pressure and temperature in the calibration box to the set reference state pressure and temperature through a pressure controller and a temperature controller, starting a light source to irradiate the pressure-sensitive coating on the surface of the sample wafer, and acquiring a surface light intensity image of the sample wafer coating by adopting a camera in the reference state;
S10, selecting a partial image area as a calibration image post-processing area, averaging the image light intensity in the reference state of the area with the light intensity image in each station to obtain the image light intensity in the reference state and the image light intensity sequence in each station, and comparing the reference light intensity with the light intensity of each station to obtain the light intensity ratio sequence (value) in each station, wherein in the step S10, the light intensity of the selected image area is more than 70% of the full-well light intensity of the camera, and has high light intensity uniformity and image signal to noise ratio;
s11, fitting the pressure value sequence, the temperature sequence and the light intensity ratio sequence set by each station to obtain a pre-test calibration fitting relational expression and a fitting curved surface of the pressure, the temperature and the light intensity ratio, wherein the specific fitting mode is as follows: the form of the pre-test calibration fitting relation adopted is a polynomial and can be expressed as follows:
wherein, P is the pressure under each station,
is the ratio of the light intensity of the image of each site to the light intensity of the reference image, T is the temperature under each site, n is the fitting order of the fitting relation, P,
T is a known quantity, and T is a known quantity,
for calibrating the coefficients, for the values to be evaluated, a least squares fit polynomial is obtained
Thus, a fitting relational expression and a fitting curved surface of the ratio of the atmospheric pressure and the ambient temperature at the coating calibration time before the test are taken as reference pressure and temperature under the temperature condition are obtained. In specific implementation, the following second-order fitting polynomial can be adopted:
So far, completing the paint calibration process before the wind tunnel test;
S12、during the wind tunnel test, a pressure sensor and a temperature sensor are adopted to measure and obtain real-time atmospheric pressure and ambient temperature in a wind tunnel test section, and the real-time atmospheric pressure and the ambient temperature are substituted into a pre-test calibration relational expression obtained by S11:
；
the ratio of the coating light intensity under atmospheric pressure and ambient temperature during the test to the coating light intensity under atmospheric pressure and ambient temperature during the calibration before the test can be obtained
And the coating light intensity under the atmospheric pressure and the ambient temperature during calibration before the test is acquired during calibration, so that the coating light intensity under the atmospheric pressure and the ambient temperature during the test can be calculated.
S13, the light intensity of the coating under atmospheric pressure and ambient temperature during the test obtained in S12 is used as the light intensity of the reference image, the light intensity values under different stations obtained during the calibration before the test are compared with the light intensity of the reference image obtained in S12 again, the light intensity ratio sequence of each station taking the atmospheric pressure and the ambient temperature under the actual wind tunnel test state as the reference condition is obtained, the pressure value sequence set by each station is fitted with the light intensity ratio sequence and the temperature sequence again, the calibration fitting relational expression and the fitting curved surface after the test of the pressure-light intensity ratio and the temperature are obtained, and the calibration fitting relational expression after the test is a polynomial and can be expressed as:
In specific implementation, the following second-order fitting polynomial can be adopted: (ii) a
Wherein, P is the pressure under each station,
is the ratio of the light intensity of the image of each site to the light intensity of the reference image, T is the temperature under each site, n is the fitting order of the fitting relation, P,
T is a known quantity, and T is a known quantity,
for calibrating the coefficients, for the values to be evaluated, it is likewise obtained by fitting a polynomial by the least-squares method
. And finishing all pressure-sensitive paint calibration processes to obtain an accurate calibration fitting relational expression and a fitting curved surface which take atmospheric pressure and ambient temperature as reference conditions during an actual wind tunnel test.
Example 1
The pressure-sensitive paint calibration sample is an aluminum round sample with the thickness of 2mm, the pressure-sensitive paint is two-component pressure-sensitive paint, and the pressure-sensitive probe is a platinum polymer. The paint calibration device is mainly composed of a UVLED excitation light source, an image data acquisition and processing subsystem, a calibration box, a temperature regulation and control subsystem, a pressure regulation and control subsystem, an automatic filtering wheel, an air supply and vacuum device and the like, as shown in FIG. 3. The UVLED excitation light source adopts a portable air-cooling ultraviolet LED light source, the image data acquisition system adopts a PCO1600 type 14-bit high-resolution scientific grade CCD color camera, the temperature regulation control subsystem is a semiconductor temperature controller, and the pressure regulation control subsystem adopts a high-precision digital pressure controller.
A method for calibrating a pressure-sensitive paint coating suitable for use in different reference conditions, as shown in fig. 4, comprising the steps of:
s1, polishing the calibration sample wafer, cleaning the surface of the sample wafer by adopting alcohol, and volatilizing a surface cleaning solvent in a clean environment until the surface of the sample wafer is dried;
s2, uniformly mixing the pressure-sensitive paint primer and acetone by using an automatic stirrer, and uniformly spraying the pressure-sensitive paint primer to the surface of the sample wafer by using a spray gun, wherein the spraying thickness of the primer is 20 microns;
s3, placing the sample wafer sprayed with the pressure-sensitive paint primer into an oven for baking, wherein the baking temperature is set to 90 ℃, and the baking time is set to 5 hours until the primer coating solvent is completely volatilized, and the primer is cured;
s4, polishing the sample wafer primer by 1500-mesh abrasive paper, detecting the roughness of the coating by a roughness meter until the surface roughness is less than 0.8, cleaning the surface of the primer by alcohol, and volatilizing a surface cleaning solvent in a clean environment until the surface of the sample wafer primer is dried;
s5, stirring the pressure-sensitive paint finish and the acetone by using an automatic stirrer until the pressure-sensitive paint finish and the acetone are completely dispersed and uniformly mixed, and uniformly spraying the pressure-sensitive paint finish onto the surface of the sample wafer by using a spray gun, wherein the spraying thickness of the finish is 20 microns;
s6, placing the sample wafer coated with the pressure-sensitive paint finish into a baking oven for baking, wherein the baking temperature is set to 65 ℃, the baking time is set to 5 hours, until the finish coating solvent is completely volatilized, the finish is cured, and the surface of the cured finish is not polished;
S7, coating heat-conducting silica gel on the surface of the sample without the pressure-sensitive paint, adhering the sample to the base of the calibration box, closing and sealing the calibration box to ensure that the calibration box is well sealed;
s8, starting coating calibration software, setting pressures and temperatures of different stations, regulating and controlling the pressure and the temperature in the calibration box to the set pressure and temperature of each station through a pressure controller and a temperature controller, starting a light source to irradiate the pressure-sensitive coating on the surface of the sample wafer, and acquiring the surface light intensity image of the coating of the sample wafer by adopting a camera under each station to obtain the coating light intensity sequence image under each station;
s9, setting reference state pressure and temperature according to atmospheric pressure and environmental temperature during calibration test, regulating and controlling the pressure and temperature in the calibration box to the set reference state pressure and temperature through a pressure controller and a temperature controller, starting a light source to irradiate the pressure-sensitive coating on the surface of the sample wafer, and acquiring a surface light intensity image of the sample wafer coating by adopting a camera in the reference state;
s10, selecting a partial area of the image with the light intensity larger than 70% of the full-well light intensity of the camera as a calibration image post-processing area, averaging the image light intensity in the reference state of the area with the light intensity image in each station to obtain the image light intensity in the reference state and the image light intensity sequence in each station, and comparing the reference light intensity with the light intensity of each station to obtain the light intensity ratio sequence (value) in each station;
S11, fitting the pressure value sequence, the light intensity ratio sequence and the temperature sequence set by each station to obtain a fitting relational expression of pressure, light intensity ratio and temperature and a fitting curved surface, and thus completing the paint calibration process before the wind tunnel test;
s12, during wind tunnel test, a pressure sensor and a temperature sensor are adopted to measure and obtain atmospheric pressure and ambient temperature in a wind tunnel test section, the light intensity ratio under the conditions of pressure and temperature in the wind tunnel body at the moment is obtained through inverse calculation according to the fitting relational expression of the pressure to light intensity ratio and temperature obtained before test, because the light intensity of the reference image in the reference state before test is known, the coating light intensity value under the atmospheric pressure and the ambient temperature during wind tunnel test can be obtained, then the light intensity value is taken as the light intensity of the reference image, the light intensity values under different stations obtained before test and the light intensity of the reference image are re-compared to obtain the light intensity ratio sequence of each station taking the atmospheric pressure and the ambient temperature under the actual wind tunnel test state as the reference condition, the pressure value sequence set by each station is re-fitted with the light intensity ratio sequence and the temperature sequence to obtain the fitting relational expression and the fitting curved surface of the pressure to the light intensity ratio and the temperature, so far, all pressure-sensitive paint calibration processes are completed, and a calibration fitting relational expression taking atmospheric pressure and ambient temperature as reference conditions during an actual wind tunnel test is obtained.
The atmospheric pressure changes by about 1 kPa in a day, and under the condition that the reference pressure changes by 1 kPa, the calibration contrast curved surface obtained by the method provided by the invention and the conventional PSP calibration method is shown in figures 5 and 6,
specifically, the relevant parameters of fig. 5 are as follows:
Linear model Poly33：
f(x,y)=p00+p10*x+p01*y+p20*x∧2+p11*x*y+p02*y ∧2+p30*X∧3+p21* x∧2*y+p12*x*y ∧2+p03*y∧3；
Coefficients(with 95% confidence bounds)：
P00=-33.51（-57.93，-9.081），P10=102.8（33.26，172.3）；
P01=-1.328（-2.739，0.08214），P20=-72.8（-142.6，-3.026）；
P11=1.51（-0.3868，3.406），P02=0.05928（-0.0005566，0.1191）；
P30=77.94（53.94，101.9），P21=-0.4512（-1.224，0.3214）；
P12=-0.02896（-0.05697，-0.0009413）；
P03=-0.0009157（-0.002223，0.0003916）；
the relevant parameters of fig. 6 are as follows:
Linear model Poly33：
f(x,y)=p00+p10*x+p01*y+p20*x∧2+p11*x*y+p02*y ∧2+p30*X∧3+p21* x∧2*y+p12*x*y ∧2+p03*y∧3；
Coefficients(with 95% confidence bounds)：
P00=-33.51（-57.93，-9.081），P10=103（33.34，172.7）；
P01=-1.328（-2.739，0.08214），P20=-73.16（-143.3，-3.041）；
P11=1.513（-0.3877，3.415），P02=0.05928（-0.0005566，0.1191）；
P30=78.52（54.34，102.7），P21=-0.4534（-1.23，0.3229）；
P12=-0.02903（-0.05711，-0.0009436）；
P03=-0.0009157（-0.002223，0.0003916）；
fig. 7 shows a model surface pressure coefficient map obtained by applying the calibration method of the present invention to a PSP test of a train locomotive model, and fig. 8 is a comparison of measurement accuracy of pressure coefficient of a locomotive model surface obtained by applying the calibration method of the present invention to a conventional calibration method, and it can be seen that the calibration curve and the calibration relationship obtained by the calibration method are slightly different from those obtained by the conventional method, and the error of the pressure coefficient finally obtained by applying the calibration method of the present invention is substantially less than 0.02, while the calibration error of the conventional calibration method is relatively large, so that the error of the pressure coefficient finally obtained is as high as about 0.05.
The calibration method for the pressure-sensitive paint coating in different reference states has the beneficial effects that: the method comprises the steps of actually measuring the atmospheric pressure and the ambient temperature in the tunnel during the wind tunnel test, and reversely calculating the coating light intensity value under the real reference condition by using the pressure-sensitive paint calibration relational expression obtained before the test, so that the accurate pressure-sensitive paint calibration relation taking the atmospheric pressure and the ambient temperature in the tunnel as the reference condition during the wind tunnel test is obtained, the calibration error is reduced, and the pressure measurement accuracy of the pressure-sensitive paint technology is improved. Secondly, aiming at certain pressure-sensitive paint and measuring equipment, the method can meet the use requirements of the pressure-sensitive paint wind tunnel test in different regions and seasons only by carrying out paint calibration once. The invention optimizes the existing pressure-sensitive paint calibration method, simplifies the pressure-sensitive paint calibration test and the preparation process before the wind tunnel test, improves the applicability and the calibration precision of the pressure-sensitive paint calibration result, and has higher popularization and application values.
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. It is therefore intended that the invention not be limited to the exact details and illustrations described and illustrated herein, but fall within the scope of the appended claims and equivalents thereof.
Claims (6)
1. A method for calibrating a pressure sensitive paint coating suitable for use in different reference conditions, comprising:
firstly, before a wind tunnel test, obtaining a pre-test calibration fitting relational expression and a fitting curved surface of the pressure-sensitive paint coating under the conditions that atmospheric pressure and ambient temperature at the calibration moment are used as reference pressure and temperature based on parameter setting of a calibration box and paint calibration software;
Step two, during wind tunnel test, reversely calculating the coating light intensity ratio under the real reference condition based on the pre-test calibration fitting relational expression by actually measuring the atmospheric pressure and the ambient temperature in the tunnel to obtain a post-test calibration fitting relational expression and a fitting curved surface of the pressure-sensitive paint coating under the condition that the atmospheric pressure and the ambient temperature in the tunnel during the wind tunnel test are used as reference conditions;
in the second step, during the wind tunnel test, the real-time atmospheric pressure P 'and the ambient temperature T' in the wind tunnel test section are measured through a pressure sensor and a temperature sensor which are arranged in the wind tunnel, and the P 'and the T' are substituted into a pre-test calibration fitting relation formula, so that the ratio of the coating light intensity under the atmospheric pressure and the ambient temperature during the test to the coating light intensity under the atmospheric pressure and the ambient temperature during the pre-test calibration is obtained
Further calculating the coating light intensity under atmospheric pressure and ambient temperature during the test;
the method comprises the following steps of taking coating light intensity under atmospheric pressure and ambient temperature during testing as reference image light intensity, obtaining light intensity value under different stations obtained during calibration before testing and reference image light intensity to be compared again, obtaining station light intensity ratio sequences taking the atmospheric pressure and the ambient temperature under the actual wind tunnel test state as reference conditions, and re-fitting pressure value sequences, the light intensity ratio sequences and the temperature sequences set by the stations to obtain a calibration fitting relational expression after testing and a fitting curved surface of the pressure-sensitive paint coating, wherein the calibration fitting relational expression after testing is a polynomial and can be expressed as follows:
Wherein, P is the pressure under each station,
the ratio of the light intensity of the image of each station to the light intensity of the reference image, T is the temperature under each station,
and n is the fitting order of the fitting relation for the calibration coefficient to be solved.
2. The method for calibrating pressure-sensitive paint coating suitable for use in different reference conditions according to claim 1, wherein in step one, the obtaining of the pre-test calibration fit relation is configured to include:
s10, preparing a test sample with pressure-sensitive paint, and arranging the test sample in a calibration box;
s11, obtaining coating light intensity sequence images under each station and coating surface light intensity images under a reference state based on hardware in the calibration box and corresponding coating calibration software;
s12, obtaining a light intensity ratio sequence under each station based on the processing of the light intensity images of the coating surface under the reference state and the light intensity sequence images of the coating under each station;
and S13, fitting the pressure value sequence, the temperature sequence and the light intensity ratio sequence set by each station to obtain a pre-test calibration fitting relational expression of the pressure, the temperature and the light intensity ratio and a fitting curved surface.
3. The method for calibrating pressure-sensitive paint coating suitable for use in different reference states according to claim 2, wherein in S10, the step of preparing the test piece is configured to include:
S101, polishing a sample wafer, cleaning the surface of the sample wafer by adopting alcohol or acetone, and volatilizing a surface cleaning solvent in a clean environment until the surface of the sample wafer is dried;
s102, stirring the pressure-sensitive paint primer and the acetone solvent until the pressure-sensitive paint primer and the acetone solvent are completely and uniformly dispersed, and uniformly spraying the pressure-sensitive paint primer on the surface of the sample wafer by using a spray gun;
s103, placing the sample wafer sprayed with the pressure-sensitive paint primer in an oven for baking until the primer coating solvent is completely volatilized, and curing the primer;
s104, polishing the priming paint of the sample by using abrasive paper, cleaning the surface of the priming paint by using alcohol, and volatilizing a surface cleaning solvent in a clean environment until the surface of the priming paint of the sample is dried;
s105, stirring the pressure-sensitive paint finish and the acetone solvent until the pressure-sensitive paint finish and the acetone solvent are completely and uniformly dispersed, and uniformly spraying the pressure-sensitive paint finish onto the surface of the sample wafer primer by using a spray gun;
s106, placing the sample wafer coated with the pressure-sensitive paint finish in an oven for baking until the solvent of the finish coating is completely volatilized, and curing the finish, wherein the surface of the cured finish is not polished;
s107, smearing the heat-conducting silica gel on the surface, without the pressure-sensitive paint, of the sample wafer, adhering and fixing the sample wafer on the base of the calibration box, closing and sealing the calibration box, and ensuring that the calibration box is well sealed.
4. The method for calibrating pressure-sensitive paint coating suitable for different reference states according to claim 2, wherein in S11, the coating light intensity sequence image acquisition mode at each station comprises:
S110, setting pressures and temperatures under different stations through coating calibration software, and adjusting the pressures and temperatures in the calibration box based on a pressure controller and a temperature controller in the calibration box so as to enable the pressures and temperatures in the calibration box to be matched with the pressures and temperatures set by each station;
s111, turning on a light source in a calibration box to irradiate the pressure-sensitive coating on the surface of the sample wafer, and collecting a light intensity image on the surface of the sample wafer coating under each station through a camera to obtain a coating light intensity sequence image corresponding to each station;
the acquisition mode of the light intensity image of the coating surface in the reference state comprises the following steps:
s112, setting reference state pressure and temperature according to atmospheric pressure and ambient temperature during a calibration test, and regulating and controlling the pressure and temperature in the calibration box through a pressure controller and a temperature controller so as to enable the pressure and temperature in the calibration box to be matched with the set reference state pressure and temperature;
s113, turning on a light source to irradiate the pressure-sensitive coating on the surface of the sample wafer, and acquiring a light intensity image of the surface of the sample wafer coating in a reference state through a camera.
5. The method for calibrating pressure-sensitive paint calibration at different reference conditions according to claim 2, wherein in S12, the obtaining of the sequence of light intensity ratios is configured to include:
S120, selecting a partial area in the image as a calibration area, and carrying out average processing on the image light intensity in the reference state and the light intensity image under each station in the calibration area to obtain the reference light intensity of the image light intensity in the reference state in the calibration area and the light intensity of each station of the image light intensity sequence under each station in the calibration area;
and S121, comparing the reference light intensity with the light intensity of each station to obtain a light intensity ratio sequence under each station.
6. The method for calibrating pressure-sensitive paint coatings for use under different reference conditions according to claim 2, wherein in S13 the pre-test calibration fit relation is expressed as:
wherein, P is the pressure under each station,
the ratio of the light intensity of each station image to the light intensity of the reference image, T is the temperature under each station,
and n is the fitting order of the fitting relation.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004070339A1 (en) * | 2003-02-04 | 2004-08-19 | Bae Systems Plc | Method of calibrating a pressure sensitive paint |
| JP2008249528A (en) * | 2007-03-30 | 2008-10-16 | Japan Aerospace Exploration Agency | Technique for correcting temperature dependency of pressure-sensitive coating measuring method by time-serial temperature change |
| CN110987360A (en) * | 2019-12-25 | 2020-04-10 | 中国空气动力研究与发展中心低速空气动力研究所 | Shock tube test system for PSP dynamic calibration device |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101290259B (en) * | 2008-06-13 | 2010-12-15 | 西北工业大学 | Optical pressure sensitive coating gauging pressure accuracy enhancing method |
| CN102928192B (en) * | 2012-10-10 | 2016-04-06 | 中国航空工业集团公司沈阳空气动力研究所 | A kind of pressure distribution modification method measured for pressure sensitive paint |
| CN105784220B (en) * | 2016-05-03 | 2018-10-09 | 中国空气动力研究与发展中心高速空气动力研究所 | A method of it improving pressure sensitive coating and measures precision |
| CN106872100B (en) * | 2017-01-12 | 2019-11-22 | 西北工业大学 | Standing wave cast optical pressure sensitive coating Dynamic pressure calibration cabin |
| CN108318215B (en) * | 2018-02-08 | 2019-09-13 | 中国空气动力研究与发展中心高速空气动力研究所 | A kind of determination method of pressure sensitive paint trial image acquisition width number |
| CN112837291B (en) * | 2021-02-03 | 2022-07-29 | 中国空气动力研究与发展中心高速空气动力研究所 | Laminar flow wing transition position measurement image processing method based on temperature-sensitive paint technology |
| CN112945501A (en) * | 2021-02-03 | 2021-06-11 | 中国空气动力研究与发展中心高速空气动力研究所 | Laminar flow wing transition position measurement test method |
| CN113155399B (en) * | 2021-04-06 | 2022-10-21 | 中国空气动力研究与发展中心高速空气动力研究所 | Synchronous measurement method for three-dimensional continuous distribution of surface pressure and deformation of high-speed aircraft |
| CN113092051B (en) * | 2021-06-07 | 2021-08-24 | 中国空气动力研究与发展中心低速空气动力研究所 | Measuring system and measuring method for dynamic pressure and flow field distribution of wind tunnel test |
-
2022
- 2022-03-14 CN CN202210244804.0A patent/CN114323548B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004070339A1 (en) * | 2003-02-04 | 2004-08-19 | Bae Systems Plc | Method of calibrating a pressure sensitive paint |
| JP2008249528A (en) * | 2007-03-30 | 2008-10-16 | Japan Aerospace Exploration Agency | Technique for correcting temperature dependency of pressure-sensitive coating measuring method by time-serial temperature change |
| CN110987360A (en) * | 2019-12-25 | 2020-04-10 | 中国空气动力研究与发展中心低速空气动力研究所 | Shock tube test system for PSP dynamic calibration device |
Non-Patent Citations (2)
| Title |
|---|
| D. Kurihara et al..Uncertainty analysis of motion-capturing pressure-sensitive paint method based on unsteady surface-pressure measurement on fluttering airfoil.《Aerospace Science and Technology》.2020,第103卷第1-7页. * |
| 李国帅 等.基于Stern－Volmer关系式的压力敏感涂料特性研究.《实验流体力学》.2012,第26卷(第3期),第76-80页. * |
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