A pressure sensitive coating dynamic characteristic measuring device and measuring method

Abstract

The present invention discloses a device for measuring the dynamic characteristics of pressure-sensitive coatings, including a PSP sample, a dynamic pressure sensor, an oscilloscope, a light source, a photomultiplier tube, a bandpass filter, a loudspeaker, a power amplifier and a signal generator; the outer surface of the PSP sample is sprayed with PSP coating; the dynamic pressure sensor is installed at the center of the PSP sample, and the output end of the dynamic pressure sensor is connected to the input end of the oscilloscope; the emission end of the light source faces the inner surface of the PSP sample; the detection end of the photomultiplier tube is installed with a bandpass filter, and the output end of the photomultiplier tube is connected to the input end of the oscilloscope; the loudspeaker faces the outer surface of the PSP sample, and the loudspeaker, the power amplifier and the signal generator are connected in sequence. The present invention also discloses a method for measuring the dynamic characteristics of pressure-sensitive coatings. The beneficial effects of the present invention are as follows: the measuring device of the present invention can generate continuous sinusoidal pressure waves of any frequency, the frequency accuracy does not exceed 0.01Hz, the optical path is not blocked, the stability is high, and the pressure frequency amplitude and phase characteristics of the PSP coating can be accurately captured.

Description

Technical Field

[0001] The invention relates to the technical field of instruments and meters, and in particular to a device and method for measuring dynamic characteristics of pressure sensitive coatings. Background Art

[0002] As one of the three thermal parameters (pressure, temperature, and flow) of automatic control, pressure plays a very important role in measurement and control. The research on pressure sensitive paint (PSP paint) pressure measurement technology based on computer vision and image processing technology is an important breakthrough in non-contact flow display technology. Compared with the traditional dot matrix measurement technology in China, the pressure sensitive paint measurement technology can make up for the damage to the model and the interference to the flow field caused by the pressure probe hole layout and pressure sensor, as well as the complexity of the traditional data transmission method. In addition, this measurement technology can greatly improve the measurement range, has the advantages of non-contact, continuous measurement, relatively low test cost, and time saving, and is favored by the majority of experimental workers.

[0003] The basic principle of pressure sensitive coating pressure measurement technology is: evenly cover the surface of the model to be tested with pressure sensitive coating, which is composed of photosensitive molecules and oxygen-permeable matrix. When excited by light of a specific wavelength, the photosensitive molecules in the coating gain energy from the originally stable ground state and transition to a high-energy excited state. The photosensitive molecules in the unstable excited state are collided with oxygen molecules diffused from the measured surface, lose the energy of the excited state and deactivate back to the ground state. This process does not produce radiation light, resulting in a decrease in luminescence intensity, forming an "oxygen quenching" phenomenon. The greater the concentration of oxygen molecules, that is, the greater the pressure in the atmosphere, the stronger the oxygen quenching effect, and the darker the light emitted by the coating under a certain light. Therefore, under light irradiation, the luminescence intensity of the pressure sensitive coating can reflect the pressure value on the surface of the model to be tested. By taking an image of the surface of the model to be tested under light irradiation, the pressure distribution on the surface of the model to be tested can be obtained by analyzing the image, which also provides a new idea for measuring the pressure distribution on the surface of the rotating model.

[0004] With the advancement of coating preparation technology, PSP measurement technology has expanded from steady-state measurement to dynamic measurement. The dynamic characteristics of pressure-sensitive coatings are important indicators for evaluating the dynamic range of coatings to adapt to flow fields, and are a necessary prerequisite for dynamic PSP measurement. At present, the measurement devices for dynamic characteristics of coatings mainly include oscillating ejectors, shock tubes, and acoustic standing wave tubes. The oscillating ejector requires not only a continuous supply of high-pressure airflow, but also the pulsating airflow generated by the oscillator is not a standard sine wave, and the pressure stability is difficult to guarantee. The principle of the shock tube is to continuously compress the air in the tube. When the air pressure is large enough, it will break through the film, causing the pressure wave to impact the PSP sample. The response time of the coating is estimated based on the PSP pressure rise time, but this device cannot measure the amplitude-frequency characteristics and phase-frequency characteristics of continuously changing pressure. The acoustic standing wave tube makes up for the shortcomings of the shock wave tube and can generate continuous sinusoidal pressure. However, due to the principle of standing wave formation, the length of the acoustic standing wave tube needs to be extended (usually more than 1m) to generate relatively low-frequency pressure waves. When the pressure wave generated by the speaker passes through the long tube to the other end of the tube, there will be pressure loss along the way, and the reflected wave of the tube wall will cause the pressure wave reaching the surface of the PSP to contain some harmonic pressure or other frequency pressure. More importantly, the acoustic standing wave tube can only be measured at the harmonic frequency of the fundamental frequency. Assuming that the fundamental frequency of the acoustic standing wave tube is 100Hz, the acoustic standing wave tube emits pressure waves of 100Hz, 200Hz, 300Hz..., and the measured frequency accuracy is equal to the fundamental frequency of the acoustic standing wave tube, and it is not possible to accurately capture the amplitude and phase characteristics of the PSP coating with pressure frequency.

[0005] Therefore, it is necessary to design a pressure sensitive coating dynamic characteristics measurement device to achieve high frequency accuracy PSP amplitude-frequency characteristics and phase-frequency characteristics measurement. Summary of the invention

[0006] The purpose of the present invention is to provide a pressure sensitive coating dynamic characteristic measuring device and measuring method in view of the deficiencies in the prior art.

[0007] The technical solution adopted by the present invention is: a device for measuring the dynamic characteristics of pressure sensitive coatings, including a PSP sample, a dynamic pressure sensor, an oscilloscope, a light source, a photomultiplier tube, a bandpass filter, a loudspeaker, a power amplifier and a signal generator; the outer surface of the PSP sample is sprayed with PSP coating; the dynamic pressure sensor is installed at the center of the PSP sample, and the output end of the dynamic pressure sensor is connected to the input end of the oscilloscope; the emitting end of the light source is facing the inner surface of the PSP sample; the detection end of the photomultiplier tube is installed with a bandpass filter, and the output end of the photomultiplier tube is connected to the input end of the oscilloscope; the loudspeaker is facing the outer surface of the PSP sample, and the loudspeaker, the power amplifier and the signal generator are connected in sequence.

[0008] According to the above scheme, the PSP sample comprises an optical glass sheet, the outer surface of which is sprayed with PSP coating; the optical glass sheet can be transparent to the light of the PSP coating and the light source.

[0009] According to the above scheme, the optical glass sheet is provided with a central hole, the dynamic pressure sensor is installed in the central hole, and the output end of the dynamic pressure sensor extends from the central hole and is electrically connected to the input end of the oscilloscope.

[0010] According to the above solution, the light source is a point laser light source.

[0011] According to the above scheme, the wavelength of the light emitted by the light source is consistent with the excitation wavelength of the PSP coating.

[0012] According to the above scheme, the bandpass filter only allows the light-emitting band of the PSP coating to pass through, and prevents the ambient light and the light emitted by the light source from entering the photomultiplier tube.

[0013] According to the above scheme, the light detection frequency range of the photomultiplier tube covers the maximum response frequency of the PSP coating.

[0014] According to the above scheme, the signals measured by the photomultiplier tube and the dynamic pressure sensor are synchronously recorded by an oscilloscope.

[0015] According to the above scheme, the loudspeaker is facing the outer surface of the PSP sample, and sends pressure waves to the outer surface of the PSP sample, and the pressure wave range covers the PSP sample.

[0016] The present invention also adopts a method for measuring dynamic characteristics of pressure sensitive coatings, which comprises the following steps:

[0017] Step 1: providing the measuring device as described above;

[0018] Step 2: Turn on the light source, and the light emitted by the light source passes through the optical glass sheet and irradiates the PSP coating, making the PSP coating glow;

[0019] Step 3: Turn on the signal generator and the speaker. The signal generator sends out a sine wave electrical signal with a lower frequency Fref, which is amplified by the power amplifier and then sent to the speaker, causing it to send out a pressure wave with the same frequency.

[0020] Step 4: The photomultiplier tube collects the fluctuating PSP paint luminescence signal, the dynamic pressure sensor synchronously collects the fluctuating PSP paint pressure signal, the oscilloscope measures the amplitude Iref of the PSP luminescence signal and the amplitude Pref of the pressure signal, and calculates the phase difference Vref through the waveforms of the two signals;

[0021] Step 5: Adjust the frequency of the signal generator with a step size of 1 Hz so that the speaker emits a sinusoidal pressure wave with a frequency of Fi, and adjust the power amplifier so that the pressure amplitude emitted by the speaker remains at Pref; the oscilloscope measures the amplitude Ii and phase difference Vi of the PSP paint luminous signal at this time;

[0022] Step 6. Repeat step 5. When the amplitude Ii drops to half of Iref, the corresponding frequency is recorded as the cutoff frequency of the PSP coating; when the amplitude Ii is close to 0, the corresponding frequency is recorded as the maximum frequency of the PSP coating, and the phase difference of the corresponding frequency is Vi-Vref.

[0023] The beneficial effects of the present invention are as follows: the measuring device of the present invention can generate continuous sinusoidal pressure waves of any frequency, the frequency accuracy does not exceed 0.01 Hz, the optical path is not blocked, the stability is high, and the pressure frequency amplitude and phase characteristics of the PSP coating can be accurately captured; the measuring device has a simple structure, and the required equipment is a common instrument and does not need to be customized; the measuring distance is short, space is saved, and pressure loss along the way is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of a specific embodiment of the present invention.

[0025] Among them: 1. Speaker; 2. PSP coating; 3. Optical glass; 4. Light source; 5. Photomultiplier tube; 6. Bandpass filter; 7. Dynamic pressure sensor; 8. Oscilloscope; 9. Power amplifier; 10. Signal generator. DETAILED DESCRIPTION

[0026] In order to better understand the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0027] like Figure 1 A pressure sensitive coating dynamic characteristic measuring device shown in the figure includes a PSP sample, a dynamic pressure sensor 7, an oscilloscope 8, a light source 4, a photomultiplier tube 5, a bandpass filter 6, a loudspeaker 1, a power amplifier 9 and a signal generator 10; the outer surface of the PSP sample is sprayed with PSP coating 2; the dynamic pressure sensor 7 is installed at the center of the PSP sample, and the output end of the dynamic pressure sensor 7 is connected to the input end of the oscilloscope 8; the emitting end of the light source 4 is facing the inner surface of the PSP sample; the detection end of the photomultiplier tube 5 is installed with a bandpass filter 6, and the output end of the photomultiplier tube 5 is connected to the input end of the oscilloscope 8; the loudspeaker 1 is facing the outer surface of the PSP sample, and the loudspeaker 1, the power amplifier 9 and the signal generator 10 are connected in sequence.

[0028] Preferably, the PSP sample comprises three pieces of optical glass, and the outer surfaces of the three pieces of optical glass are sprayed with PSP coating 2 ; the three pieces of optical glass can be transparent to light emitted by the PSP coating 2 and the light source 4 .

[0029] Preferably, the optical glass 3 is provided with a central hole, and the dynamic pressure sensor 7 is installed in the central hole. The output end of the dynamic pressure sensor 7 extends out from the central hole and is electrically connected to the input end of the oscilloscope 8 .

[0030] In the present invention, the dynamic pressure sensor 7 is used to detect the dynamic pressure of the PSP coating 2 on the PSP sample. In order to reduce light path obstruction and measurement error, the head size of the dynamic pressure sensor 7 is as small as possible; in order to cover the possible maximum response frequency of the PSP coating 2, the dynamic pressure sensor 7 can detect a pressure frequency range as large as possible.

[0031] Preferably, the light source 4 is a point laser light source, the wavelength of the light emitted by the light source 4 is consistent with the excitation wavelength of the PSP coating 2, and the light power stability should be good enough.

[0032] Preferably, the bandpass filter 6 allows only the light-emitting wavelength band of the PSP coating 2 to pass through, and prevents ambient light and light emitted by the light source 4 from entering the photomultiplier tube 5 .

[0033] Preferably, the light detection frequency range of the photomultiplier tube 5 covers the maximum response frequency of the PSP coating 2 .

[0034] Preferably, the signals measured by the photomultiplier tube 5 and the dynamic pressure sensor 7 are synchronously recorded by an oscilloscope 8 .

[0035] Preferably, the speaker 1 faces the outer surface of the PSP sample (i.e., the side sprayed with the PSP coating 2), and sends pressure waves to the outer surface of the PSP sample, and the pressure wave range covers the PSP sample. In the present invention, in order to reduce the loss of pressure wave capacity, the distance between the PSP sample and the speaker 1 is as small as possible, which can be 5 cm to 10 cm.

[0036] In the present invention, the signal generator 10 generates a sinusoidal signal, which is amplified by the power amplifier 9 and transmitted to the speaker 1, so that the speaker 1 emits a sinusoidal pressure wave of a specific frequency, and the pressure amplitude and frequency generated by the speaker 1 are as high as possible.

[0037] A method for measuring dynamic characteristics of a pressure sensitive coating, the method comprising the following steps:

[0038] Step 1: Provide the measuring device as described above and ensure that the measuring environment is a dark environment without stray light;

[0039] Step 2, turn on the light source 4, the light emitted by the light source 4 passes through the optical glass 3 and then irradiates the PSP coating 2, so that the PSP coating 2 emits light;

[0040] Step 3: Turn on the signal generator 10 and the speaker 1. The signal generator 10 sends a sine wave electrical signal with a reference frequency Fref=10 Hz, which is amplified by the power amplifier 9 and sent to the speaker 1 to make it send a pressure wave with the same frequency.

[0041] Step 4, the photomultiplier tube 5 collects the fluctuating luminescence signal of the PSP coating 2, the dynamic pressure sensor 7 synchronously collects the fluctuating pressure signal of the PSP coating 2, the oscilloscope 8 measures the amplitude Iref of the PSP luminescence signal and the amplitude Pref of the pressure signal, and calculates the phase difference Vref through the waveforms of the two signals;

[0042] Step 5: Adjust the frequency of the signal generator 10 with a step size of 1 Hz, so that the speaker 1 emits a sinusoidal pressure wave with a frequency of Fi, and adjust the power amplifier 9 so that the pressure amplitude emitted by the speaker 1 is still Pref; the oscilloscope 8 measures the amplitude Ii and the phase difference Vi of the luminous signal of the PSP coating 2 at this time;

[0043] Step 6: Repeat step 5. When the amplitude Ii drops to half of Iref, the corresponding frequency is recorded as the cutoff frequency of PSP coating 2; when the amplitude Ii is close to 0, the corresponding frequency is recorded as the maximum frequency of PSP coating 2, and the phase difference of the corresponding frequency is Vi-Vref.

[0044] After testing, the measuring device of the present invention can generate continuous sinusoidal pressure waves of any frequency, and the frequency accuracy does not exceed 0.01 Hz. The contents not described in detail in this specification belong to the prior art known to professionals in this field.

[0045] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein with equivalents. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for measuring dynamic characteristics of pressure sensitive coatings, characterized in that: The method comprises the following steps: Step 1: Provide a pressure sensitive coating dynamic characteristic measurement device; Step 2: Turn on the light source, and the light emitted by the light source passes through the optical glass sheet and irradiates the PSP coating, making the PSP coating glow; Step 3: Turn on the signal generator and the speaker. The signal generator sends out a sine wave electrical signal with a lower frequency Fref, which is amplified by the power amplifier and then sent to the speaker, causing it to send out a pressure wave with the same frequency. Step 4: The photomultiplier tube collects the fluctuating PSP paint luminescence signal, the dynamic pressure sensor synchronously collects the fluctuating PSP paint pressure signal, the oscilloscope measures the amplitude Iref of the PSP luminescence signal and the amplitude Pref of the pressure signal, and calculates the phase difference Vref through the waveforms of the two signals; Step 5: Adjust the frequency of the signal generator with a step size of 1 Hz so that the speaker emits a sinusoidal pressure wave with a frequency of Fi, and adjust the power amplifier so that the pressure amplitude emitted by the speaker remains at Pref; the oscilloscope measures the amplitude Ii and phase difference Vi of the PSP paint luminous signal at this time; Step 6: Repeat step 5. When the amplitude Ii drops to half of Iref, the corresponding frequency is recorded as the cutoff frequency of the PSP coating. When the amplitude Ii is close to 0, the corresponding frequency is recorded as the maximum frequency of the PSP coating, and the phase difference of the corresponding frequency is Vi-Vref. The dynamic characteristic measuring device of pressure sensitive coating includes a PSP sample, a dynamic pressure sensor, an oscilloscope, a light source, a photomultiplier tube, a bandpass filter, a loudspeaker, a power amplifier and a signal generator; the outer surface of the PSP sample is sprayed with PSP coating; the dynamic pressure sensor is installed at the center of the PSP sample, and the output end of the dynamic pressure sensor is connected to the input end of the oscilloscope; the emitting end of the light source faces the inner surface of the PSP sample; the detection end of the photomultiplier tube is installed with a bandpass filter, and the output end of the photomultiplier tube is connected to the input end of the oscilloscope; the loudspeaker faces the outer surface of the PSP sample, and the loudspeaker, the power amplifier and the signal generator are connected in sequence.

2. The method for measuring dynamic characteristics of pressure sensitive coatings according to claim 1, characterized in that: The PSP sample comprises an optical glass sheet, the outer surface of which is sprayed with PSP coating; the optical glass sheet can be transparent to the light of the PSP coating and the light source.

3. The method for measuring dynamic characteristics of pressure sensitive coatings according to claim 2, characterized in that: The optical glass sheet is provided with a central hole, the dynamic pressure sensor is installed in the central hole, and the output end of the dynamic pressure sensor extends out from the central hole and is electrically connected to the input end of the oscilloscope.

4. The method for measuring dynamic characteristics of pressure sensitive coatings according to claim 2, characterized in that: The light source is a point laser light source.

5. The method for measuring dynamic characteristics of pressure sensitive coatings according to claim 4, characterized in that: The wavelength of light emitted by the light source is consistent with the excitation wavelength of the PSP coating.

6. The method for measuring dynamic characteristics of pressure sensitive coatings according to claim 2, characterized in that: The bandpass filter only allows the light-emitting band of the PSP paint to pass through, and blocks the ambient light and the light emitted by the light source from entering the photomultiplier tube.

7. The method for measuring dynamic characteristics of pressure sensitive coatings according to claim 1, characterized in that: The light detection frequency range of the photomultiplier tube covers the maximum response frequency of the PSP coating.

8. The method for measuring dynamic characteristics of pressure sensitive coatings according to claim 1, characterized in that: The signals measured by the photomultiplier tube and the dynamic pressure sensor are recorded synchronously by an oscilloscope.

9. The method for measuring dynamic characteristics of pressure sensitive coatings according to claim 1, characterized in that: The loudspeaker faces the outer surface of the PSP sample and sends pressure waves to the outer surface of the PSP sample, and the pressure wave range covers the PSP sample.

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