Sensitised paint window based compressor casing wall pressure measurement system and method

Abstract

The present application relates to the technical field of pressure measurement of impeller machinery, and particularly relates to a compressor casing wall pressure measurement system and method based on sensitive paint window. The measurement system comprises optical pressure sensitive paint, optical window, CCD camera, optical filter, LED light source, digital signal generator, lock-in sensor and the like. An optical window is opened on the casing, and a transparent primer is sprayed on the inner wall of the window, and then a luminous finish is sprayed. The excitation light of the optical pressure sensitive paint first transmits through the optical window, then passes through the transparent primer, and finally reaches the paint finish, so as to realize the excitation of the paint. After the optical pressure sensitive paint is excited, the emitted light first transmits through the primer, then passes through the optical window, and finally is captured by the camera, so as to realize the image acquisition. Two image acquisition methods based on the reverse of the optical window are proposed, which can realize the measurement of transient and circumferential average pressure of the compressor casing wall with full domain, high spatial resolution and high signal-to-noise ratio.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pressure measurement of impeller machinery. BACKGROUND

[0002] The compressor casing is an envelope component of an aero-engine, and its surface contains rich flow information, which can represent the development of the boundary layer flow state, identify the trajectory of the tip leakage flow, the intensity and position of the shock wave, and distinguish the flow instability of the compressor. Therefore, obtaining the pressure distribution on the surface of the compressor blade can provide key data support for the aerodynamic design of the aero-engine, the analysis of the flow mechanism, and the verification of the accuracy of CFD, and is an important way to improve the performance of the compressor.

[0003] Traditional pressure measurement methods include pressure holes and pressure sensors for contact measurement. Both of these measurement methods are single-point measurement methods, and only single-point pressure data at fixed positions can be obtained. Therefore, multiple sensors are usually arranged during testing to obtain more and larger range of pressure field data.

[0004] The structure of the aero-engine compressor test bench is compact, and the measurement space is small. Due to the limitation of the small space and the volume of the test element, the installation of the test element is difficult, which greatly limits the number of pressure measurement points, and only a small number of sensors can be arranged, so that the spatial resolution of the measured flow information is very limited. The traditional pressure measurement method lacks data in the important measurement area, and it is difficult to capture the flow details of the flow field. And the space limitation of the test bench makes it difficult to lay out the signal leads of the sensors. At the same time, a series of pre-test preparations require a large amount of manual and time costs, and the pressure sensor is high in cost, easy to damage and short in service life.

[0005] With the continuous development of pressure measurement technology, the optical pressure sensitive paint (PSP) pressure measurement technology provides a realizable means for the fine measurement of the global pressure on the surface of the aero-engine component, has the advantages of high spatial resolution, non-invasive and non-destructive measurement, and makes the PSP measurement technology continuously develop and improve. This technology uses the photodynamic characteristics of organic fluorescent molecules under different oxygen partial pressures to make the chemical sensor array of molecular scale in the paint reflect the air pressure acting on the solid wall. When the optical pressure sensitive paint is excited by a light source of a specific wavelength, the luminous intensity and lifetime of the paint show sensitivity to the pressure on the model surface, and thus the quantitative relationship between the pressure on the model surface and the luminous intensity of the PSP can be obtained. By using a camera to shoot the PSP luminous image, the global pressure distribution on the model surface can be obtained after image processing and calibration.

[0006] Therefore, in view of the pressure measurement requirements and problems of the compressor casing wall, a compressor casing wall pressure measurement method of pressure sensitive paint in a limited test space is needed to provide theoretical support and technical reserves for fine pressure measurement of the compressor casing wall of the aero-engine. SUMMARY

[0007] The present application aims to avoid the deficiencies of the prior art and provide a compressor casing wall pressure measurement system and method based on sensitive coating windows, which considers the measurement requirements of the casing wall pressure, adopts optical pressure sensitive paint pressure measurement technology, realizes the measurement and acquisition of the compressor casing wall pressure with full domain, high spatial resolution and high signal-to-noise ratio, effectively solves the problems of limited number of pressure measurement points, insufficient spatial resolution and unmeasurable pressure, and is not limited by the light path.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a compressor casing wall pressure measurement system based on sensitive coating windows, comprising a compressor casing to be measured, a rotating shaft and a rotor blade in the compressor casing;

[0009] An optical window is opened on the compressor casing, and an optical pressure sensitive paint is sprayed on the inner wall surface of the optical window;

[0010] A CCD camera for shooting and collecting images and an LED light source for exciting the optical pressure sensitive paint are fixedly installed on the corresponding side of the optical window, a camera lens is installed on the CCD camera, a narrow-band filter is installed in front of the camera lens for filtering out the excitation light of the LED light source;

[0011] The LED light source is electrically connected to a digital signal generator through a second data transmission line, and the digital signal generator is used to send a pulse signal to control the LED light source to emit excitation light;

[0012] The CCD camera is electrically connected to a computer through a first data transmission line, and the CCD camera sends the collected images to the computer;

[0013] The collected images are the luminescence images of the optical pressure sensitive paint on the compressor casing wall, and the pressure of the compressor casing wall corresponding to the luminescence images is obtained.

[0014] Further, the optical window is quartz glass to improve the transmittance of the excitation light of the optical pressure sensitive paint;

[0015] The optical pressure sensitive paint is composed of a transparent primer and a luminescent finish, the transparent primer is first sprayed on the inner wall surface of the optical window, baked and dried, then the luminescent finish is sprayed on the transparent primer, and then image registration mark points are made on the luminescent finish for image registration;

[0016] The excitation light of the LED light source first transmits through the optical window, then passes through the transparent primer, and finally reaches the luminous finish, so that the optical pressure sensitive paint is excited; when the optical pressure sensitive paint is excited, the emission light of the optical pressure sensitive paint first transmits through the transparent primer, then transmits through the optical window, and finally is captured by the CCD camera, so that the collection of the luminescent image of the optical pressure sensitive paint is realized.

[0017] Further, the camera lens is installed on the CCD camera through an adapter ring.

[0018] Further, the bandwidth of the narrow bandpass filter is 650+15nm, and the peak wavelength of the LED light source is 405+17nm.

[0019] Further, the optical platform is further provided, and the optical platform is arranged at the optical window.

[0020] Further, the optical platform is further provided, and the optical platform is arranged at the optical window.

[0021] The phase-locked patch is attached to the rotating shaft at the inlet of the compressor, and a phase-locked sensor is arranged on the corresponding side of the phase-locked patch; the phase-locked sensor is electrically connected to the external trigger port of the digital signal generator through a third data transmission line, and the digital signal generator controls the LED light source to emit excitation light through the external trigger signal emitted by the phase-locked sensor.

[0022] Further, the phase-locked sensor is fixed on the tripod at a position more than 2m away from the inlet of the compressor, and the phase-locked sensor is arranged opposite to the phase-locked patch.

[0023] At the same time, the exposed area of the rotating shaft outside the phase-locked patch is blackened to ensure the normal triggering of the phase-locked patch.

[0024] The application also provides a measurement method realized by the compressor casing wall pressure measurement system based on the sensitive paint window, and the measurement method is realized by collecting the luminescent image of the optical pressure sensitive paint after the phase-locked sensor is phase-locked, and the transient pressure measurement of the compressor casing wall is realized, and the specific steps include:

[0025] The actual working condition of the compressor is taken as the measurement actual working condition, and in the actual working condition:

[0026] Firstly, the LED light source is set to pulse working mode, the pulse width time of the light source is determined according to the tip speed in the experimental working condition, and the pulse width time of the pulse signal for controlling the light emission of the LED light source is set on the digital signal generator;

[0027] The pulse width time is the time when the light source irradiates the optical pressure sensitive paint at the same phase of the compressor rotor, and the image captured when the pulse width time is too long will be blurred.

[0028] Secondly, the photoelectric lock-in sensor emits laser light, and when the lock-in patch sweeps across the laser light emitted by the lock-in sensor each time, the photoelectric lock-in sensor receives the reflected light signal of the lock-in patch, and then converts the external trigger excitation signal into an external trigger excitation signal, which is transmitted to the external trigger port of the digital signal generator as an external trigger signal for controlling the LED light source to perform pulsed stroboscopic light;

[0029] Subsequently, the actual working condition of the environmental light is turned off, and the LED light source is turned on to pulse the optical pressure sensitive paint, and the CCD camera continuously collects, and when the image gray value reaches 1 / 2~3 / 4 of the camera full well value, the exposure time of the CCD camera is determined to prevent overexposure.

[0030] Finally, during the excitation of the optical pressure sensitive paint by the excitation light, the CCD camera works continuously, and the shutter is in an open state. Each time the optical pressure sensitive paint is excited by the excitation light, the CCD camera records the light emission image. After continuous pulsed excitation of the optical pressure sensitive paint for multiple times, the light emission images are continuously superimposed, and finally, the first light emission image of the compressor casing wall surface with high signal-to-noise ratio is obtained.

[0031] The state of the compressor after shutdown is taken as the reference state for measurement, and in the reference state:

[0032] First, the experimental environment light is turned off, and the LED light source is turned on to keep the pulse width time consistent with that of the light source in the actual working condition. The CCD camera is used to continuously collect, and the exposure time is consistent with that in the actual working condition. The first reference image is obtained by shooting, and the corresponding compressor casing wall surface pressure is the atmospheric pressure in the experimental environment, which is recorded as the first windless pressure P0. P ref1 ;

[0033] Next, the environmental light source and the LED light source are turned off, and the first dark background image is captured by using the CCD camera.

[0034] Finally, the light emission intensity of the first light emission image and the light emission intensity of the first reference image are used to subtract the first intensity value of the first dark background image I d1 ;

[0035] Further, according to the pressure-light intensity calibration relationship obtained by calibration:

[0036]

[0037] In the formula, I ref1 Subtract the first intensity valueI d1 the first reference image luminous intensity; I 1 is the first intensity value I d1 the first luminous image luminous intensity; T is the temperature of the optical window wall surface, A , B is the temperature coefficient, P 1 is the first transient pressure of the compressor casing wall surface corresponding to the first luminous image.

[0038] Further, before the measurement method starts, the blade, the blade tip and the casing area around the optical window are sprayed with black paint.

[0039] The application also provides another measurement method implemented by the compressor casing wall surface pressure measurement system based on the sensitive paint window as described above, and the measurement method is the circumferential average pressure distribution of the compressor casing wall surface obtained by the long-time exposure of the CCD camera to collect the luminous image of the optical pressure sensitive paint, comprising the following steps:

[0040] The compressor shutdown state is taken as the reference state of the measurement, and in the reference state:

[0041] Firstly, the exposure time of the CCD camera is determined to prevent overexposure;

[0042] Then, the ambient light source and the LED light source are turned off, and the second dark background image is captured by the CCD camera;

[0043] Finally, the LED light source is set to the constant light mode, and the CCD camera is set to the long exposure mode; then, the excitation light emitted by the LED light source continuously excites the optical pressure sensitive paint, and the second reference image is captured by the CCD camera, and the corresponding compressor casing wall surface pressure is the atmospheric pressure in the experimental environment, which is recorded as the second windless pressure P ref2 ;

[0044] The running working state of the compressor is taken as the actual working condition state of the measurement, and in the actual working condition state:

[0045] The LED light source is set to the constant light mode, and the CCD camera is set to the long exposure mode, that is, the setting is consistent with that in the reference state, the excitation light of the LED light source continuously excites the optical pressure sensitive paint, and the second luminous image is captured by the CCD camera;

[0046] Finally, the luminous intensity of the second luminous image and the luminous intensity of the second reference image are used to subtract the second intensity value I d2 of the second dark background image, respectively.

[0047] Further, according to the pressure-light intensity calibration relation obtained by calibration:

[0048]

[0049] In the formula, I ref2 The second reference image luminous intensity is subtracted from the second intensity value I d2 The second luminous image luminous intensity is subtracted from the second intensity value I 2 The second luminous image luminous intensity is subtracted from the second intensity value I d2 The temperature of the optical window wall surface is T , A ,The temperature coefficient is B 2 The second circumferential average pressure of the compressor casing wall surface is P

[0050] The beneficial effects of the present application are:

[0051] (1) The compressor casing wall surface pressure measurement system and method provided by the present application can realize the measurement and acquisition of the compressor casing wall surface pressure with full domain, high spatial resolution and high signal-to-noise ratio;

[0052] (2) The two pressure measurement methods proposed can realize the acquisition of the transient and circumferential average pressure of the compressor casing wall surface, and can also be extended to the unsteady measurement of the casing wall surface pressure;

[0053] (3) The problems of limited number of pressure measurement points, insufficient spatial resolution and undetectable pressure can be effectively solved;

[0054] (4) Not limited by the light path, the light path layout is easy, and the test cycle can be shortened;

[0055] (5) Reusable, simple optical window structure, easy to process, low cost, and does not damage the aerodynamic layout, has the advantages of non-destructive measurement;

[0056] (6) The high-precision phase-locked system adopted can realize long-distance data transmission and phase locking, has high precision and good economy. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 is a schematic diagram of the pressure measurement system of the present application;

[0058] Figure 2 is a schematic diagram of the optical pressure sensitive coating measurement principle of the reverse side of the optical window of the present application;

[0059] Figure 3 is a timing diagram of the working of the LED light source and the CCD camera in the measurement method of embodiment 5 of the present application;

[0060] Figure 4 A timing diagram of the working of the LED light source and the CCD camera in the method of measuring embodiment 6 of the present application.

[0061] In the figure, 1, compressor casing; 2, rotor blade; 3, rotating shaft; 4, phase-locked sensor; 5, phase-locked patch; 6, optical platform; 7, optical pressure-sensitive paint; 8, optical window; 9, narrow band-pass filter; 10, camera lens; 11, CCD camera; 12, LED light source; 13, digital signal generator; 14, second data transmission line; 15, third data transmission line; 16, first data transmission line; 17, computer; 18, transparent primer; 19, luminous finish; 20, airflow direction; 21, working timing of the LED light source in embodiment 5; 22, working timing of the CCD camera in embodiment 5; 23, working timing of the LED light source in embodiment 6; 24, working timing of the CCD camera in embodiment 6. DETAILED DESCRIPTION

[0062] The principles and features of the present application are described below in conjunction with the accompanying drawings, and the examples are used only to explain the present application and are not intended to limit the scope of the present application.

[0063] The compressor casing wall pressure-sensitive paint pressure measurement system and method based on the optical window can realize the measurement and acquisition of the compressor casing wall pressure with full domain, high spatial resolution and high signal-to-noise ratio. The two pressure measurement methods can realize the acquisition of the transient and circumferential average pressure of the compressor casing wall, effectively solve the problems of limited number of pressure measurement points, insufficient spatial resolution and unmeasurable pressure, and are not limited by the optical path, and the optical path layout is easy, which can shorten the test cycle.

[0064] In addition, the compressor casing wall pressure-sensitive paint pressure measurement system and method based on the optical window can be reused, the optical window has a simple structure, is easy to process, has low cost, does not damage the aerodynamic layout, can be popularized to the measurement of unsteady pressure of the casing wall and the internal rotor of the aero-engine, and has wide application prospect and measurement advantage in the field of aerospace.

[0065] In order to achieve the above-mentioned purpose, the present application provides the following specific embodiments:

[0066] Embodiment 1: as shown in Figure 1 , Figure 2 , a compressor casing wall pressure measurement system based on a sensitive paint window, as shown in Figure 1 , comprising a compressor casing to be measured 1, and a rotating shaft 3 and a rotor blade 2 in the compressor casing 1.

[0067] An optical window 8 is provided on the compressor casing 1, and the optical window 8 is made of quartz glass to improve the transmittance of the excitation light of the optical pressure sensitive paint;

[0068] As shown in the figure, the optical pressure sensitive paint 7 is sprayed on the inner wall surface of the optical window 8, and the optical pressure sensitive paint 7 is composed of a transparent primer 18 and a luminescent finish 19. The transparent primer is first sprayed on the inner wall surface of the optical window 8, and then the luminescent finish is sprayed on the transparent primer after baking. Then, the mark points for image registration are made on the luminescent finish 19 for image registration. Figure 2

[0069] The excitation light of the LED light source 12 first transmits through the optical window 8, then passes through the transparent primer 18, and finally reaches the luminescent finish 19, so as to realize the excitation of the optical pressure sensitive paint. After the optical pressure sensitive paint is excited, the emitted light of the optical pressure sensitive paint 7 first transmits through the transparent primer 18, then transmits through the optical window 8, and finally is captured by the CCD camera 11, so as to realize the collection of the luminescent image of the optical pressure sensitive paint.

[0070] The CCD camera 11 for shooting and collecting images and the LED light source 12 for exciting the optical pressure sensitive paint are fixedly installed on the optical platform 6 corresponding to the side of the optical window 8. The camera lens 10 is installed on the CCD camera 11 through an adapter ring, and a narrow band filter 9 is installed in front of the camera lens 10 for filtering out the excitation light of the LED light source 12.

[0071] The LED light source 12 is electrically connected to the digital signal generator 13 through the second data transmission line 14, and the digital signal generator 13 is used to send a pulse signal to control the LED light source 12 to emit excitation light.

[0072] The CCD camera 11 is electrically connected to the computer 17 through the first data transmission line 16, and the CCD camera 11 sends the collected images to the computer 17.

[0073] The collected images are the luminescent images of the optical pressure sensitive paint on the compressor casing wall surface, and then the pressure of the compressor casing wall surface corresponding to the luminescent images is obtained.

[0074] A phase-locked patch 5 is attached to the rotating shaft 3 at the inlet of the compressor, and a phase-locked sensor 4 is arranged on the corresponding side of the phase-locked patch 5.

[0075] The phase-locked sensor 4 is electrically connected to the external trigger port of the digital signal generator 13 through the third data transmission line 15, and the digital signal generator 13 controls the LED light source 12 to emit excitation light through the external trigger signal sent by the phase-locked sensor 4.

[0076] ​The phase-locked sensor 4 is fixed by a tripod at a position more than 2m away from the compressor inlet, and the phase-locked sensor 4 is positioned directly opposite the phase-locked patch 5;

[0077] Meanwhile, the exposed area of ​​the rotating shaft 3 outside the phase-locked patch 5 is sprayed black to ensure normal triggering of the phase-locked circuit.

[0078] Example 2: Same as Example 1, except that the bandwidth of the narrowband filter 9 is 650±15nm and the peak wavelength of the LED light source 12 is 405±17nm.

[0079] Example 3: As Figure 1 , Figure 2 A compressor casing wall pressure measurement system based on a sensitive coating window, such as Figure 1 The test includes the compressor casing 1 to be tested, and the rotating shaft 3 and rotor blades 2 inside the compressor casing 1.

[0080] An optical window 8 is provided on the compressor housing 1. The optical window 8 is made of quartz glass and is used to improve the transmittance of the light excitation by the optical pressure-sensitive coating.

[0081] Optical pressure-sensitive coating 7 is sprayed onto the inner wall of optical window 8. Optical pressure-sensitive coating 7 consists of transparent primer 18 and luminescent topcoat 19. First, the transparent primer is sprayed onto the inner wall of optical window 8 and baked dry. Then, the luminescent topcoat is sprayed onto the transparent primer. Then, image registration markers are made on the luminescent topcoat 19 for image registration.

[0082] like Figure 2 As shown, the excitation light from the LED light source 12 first passes through the optical window 8, then through the transparent primer 18, and finally reaches the luminescent topcoat 19, thereby realizing the excitation of the optical pressure-sensitive coating. When the optical pressure-sensitive coating 7 is excited, the emitted light of the optical pressure-sensitive coating 7 first passes through the transparent primer 18, then through the optical window 8, and is finally captured by the CCD camera 11, thereby realizing the acquisition of the luminescent image of the optical pressure-sensitive coating.

[0083] A CCD camera 11 for capturing and acquiring images and an LED light source 12 for exciting optical pressure-sensitive coating are fixedly mounted on the corresponding side of the optical window 8. The camera lens 10 is mounted on the CCD camera 11 via an adapter ring. A narrow bandpass filter 9 is installed in front of the camera lens 10 to filter out the excitation light from the LED light source 12.

[0084] LED light source 12 is electrically connected to digital signal generator 13 via second data transmission line 14. Digital signal generator 13 is used to send pulse signals to control LED light source 12 to emit excitation light.

[0085] The CCD camera 11 is electrically connected with the computer 17 through the first data transmission line 16, and the CCD camera 11 sends the collected image to the computer 17;

[0086] The collected image is the luminescence image of the optical pressure sensitive paint on the compressor casing wall surface, and the pressure of the compressor casing wall surface corresponding to the luminescence image is obtained;

[0087] The optical platform 6 is further included, and the optical platform 6 is arranged at the optical window 8, and the CCD camera 11 and the LED light source 12 are fixedly installed on the optical platform 6.

[0088] In example 4, the bandwidth of the narrow band filter 9 is 650±15 nm, and the peak wavelength of the LED light source 12 is 405±17 nm.

[0089] In example 5, as shown in the figure, the application further provides a measurement method realized by the pressure measurement system in examples 1 and 2. Figure 3 The measurement method is used for measuring the transient pressure of the compressor casing wall surface by collecting the luminescence image of the optical pressure sensitive paint after the phase-locked sensor 4 is phase-locked, and the specific steps include:

[0090] The actual working state of the compressor is taken as the actual working state of the measurement, and the actual working state is:

[0091] The casing area around the blade, the blade tip and the optical window 8 is sprayed with black paint.

[0092] Firstly, the LED light source 12 is set to the pulse working mode, the pulse width time of the light source is determined according to the blade tip speed under the experimental working condition, and the pulse width time of the pulse signal for controlling the light emission of the LED light source 12 is set on the digital signal generator 13;

[0093] The pulse width time is the time for the light source to irradiate the optical pressure sensitive paint 7 at the same phase of the compressor rotor, and the image taken when the pulse width time is too long will be blurred.

[0094] Secondly, the photoelectric phase-locked sensor 4 emits laser light, and when the phase-locked patch 5 sweeps the laser light emitted by the phase-locked sensor 4 each time, the photoelectric phase-locked sensor 4 receives the reflected light signal of the phase-locked patch 5, and then converts the reflected light signal into an external trigger excitation signal, and then transmits the external trigger excitation signal to the external trigger port of the digital signal generator 13 as an external trigger signal for controlling the LED light source 12 to perform pulse stroboscopic;

[0095] Subsequently, the actual working condition ambient light is turned off, the LED light source 12 is turned on to pulse excite the optical pressure sensitive paint, the CCD camera 11 continuously acquires, and when the image gray value reaches 1 / 2-3 / 4 of the camera full well value, the exposure time of the CCD camera 11 is determined, so as to prevent overexposure;

[0096] Finally, during the excitation light excitation of the optical pressure sensitive paint 7, the CCD camera 11 continuously works, the shutter is in an open state, and the CCD camera 11 records the luminescence image each time the optical pressure sensitive paint 7 is excited by the excitation light. At this time, the LED light source 12 and the CCD camera 11 work according to the working time sequence as shown in Figure 3 , wherein the reference numerals 21 and 22 in the figure are the working time sequence lines of the LED light source 12 and the CCD camera 11 in the embodiment;

[0097] After the optical pressure sensitive paint 7 is continuously excited by multiple times of pulse excitation, the luminescence images are continuously superimposed, and finally, the first luminescence image of the compressor casing wall surface with high signal-to-noise ratio is obtained;

[0098] The state after the compressor is stopped is taken as the reference state of measurement, and in the reference state:

[0099] First, the experimental ambient light is turned off, the LED light source 12 is turned on, the pulse width time of the light source is consistent with that in the actual working condition, the CCD camera 11 is continuously acquired, the exposure time is consistent with that in the actual working condition, and the first reference image is obtained by shooting, and the corresponding compressor casing wall surface pressure is the atmospheric pressure in the experimental environment, which is recorded as the first windless pressure P0. P ref1 At this time, the LED light source 12 and the CCD camera 11 still work according to the working time sequence as shown in Figure 3 ;

[0100] Then, the ambient light source and the LED light source are turned off, and the first dark background image is shot by using the CCD camera;

[0101] Finally, the luminescence intensity of the first luminescence image and the luminescence intensity of the first reference image are respectively subtracted by the first intensity value I0 of the first dark background image I d1 ;

[0102] Further, according to the pressure-luminescence intensity calibration relationship obtained by calibration:

[0103]

[0104] In the formula, I ref1 The first reference image luminescence intensity is subtracted by the first intensity value I0 I d1 ; and I1 is the first intensity value I d1 the first luminous image luminous intensity; T is the temperature of the optical window wall surface, A , B is the temperature coefficient, P 1 is the first transient pressure of the compressor casing wall surface corresponding to the first luminous image;

[0105] that is, the first transient pressure of the compressor casing wall surface corresponding to the first luminous image is calculated through the pressure-luminous intensity calibration relationship P 1.

[0106] Embodiment 6: The present application also provides a measurement method realized by the sensitive coating window-based compressor casing wall surface pressure measurement system as described in Embodiments 3 and 4, which is the compressor casing wall surface circumferential average pressure distribution obtained by the long-time exposure of the CCD camera 11 to collect the luminous image of the optical pressure sensitive coating, comprising the following steps:

[0107] Taking the compressor shutdown state as the reference state of measurement, and in the reference state:

[0108] First, determine the exposure time of the CCD camera 11 to prevent overexposure;

[0109] Next, turn off the ambient light source and the LED light source 12, and use the CCD camera 11 to take a second dark background image;

[0110] Finally, set the LED light source 12 to a constant light mode and the CCD camera 11 to a long exposure mode; then, use the excitation light emitted by the LED light source 12 to continuously excite the optical pressure sensitive coating 7, and use the CCD camera 11 to take a first reference image, corresponding to the compressor casing wall surface pressure is the atmospheric pressure in the experimental environment, denoted as the second windless pressure P ref2 ; At this time, the LED light source 12 and the CCD camera 11 work according to the working time sequence as shown in Figure 4 , in which the labels 23 and 24 are the working time sequence lines of the LED light source 12 and the CCD camera 11 in this embodiment;

[0111] Taking the running working state of the compressor as the actual working condition state of measurement, and in the actual working condition state:

[0112] Set the LED light source 12 to a constant light mode and the CCD camera 11 to a long exposure mode, that is, consistent with the setting in the reference state, use the excitation light of the LED light source 12 to continuously excite the optical pressure sensitive coating 7, and use the CCD camera 11 to take a second luminous image, at this time, the LED light source 12 and the CCD camera 11 still work according to the working time sequence as shown inFigure 4 The working timing shown is used for working;

[0113] Finally, using the light emission intensity of the second light emission image and the light emission intensity of the second reference image, the second intensity value of the second dark background image is subtracted respectively I d2 ;

[0114] Further, according to the pressure-light intensity calibration relation obtained by calibration:

[0115]

[0116] In the formula, I ref2 The second intensity value is subtracted I d2 The light emission intensity of the second reference image, I 2 The second intensity value is subtracted I d2 The light emission intensity of the second light emission image, T The temperature of the optical window wall surface, A , B The temperature coefficient, P 2 The second circumferential average pressure of the compressor casing wall surface;

[0117] That is, the second circumferential average pressure of the compressor casing wall surface P 2 is calculated by the pressure-light intensity calibration relation.

[0118] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A sensitive paint window based compressor casing wall pressure measurement system, characterized by, The compressor casing to be measured, a rotating shaft and a rotor blade in the compressor casing; An optical window is arranged on the compressor casing, and an optical pressure-sensitive coating is sprayed on the inner wall surface of the optical window; A CCD camera for shooting and collecting images and an LED light source for exciting the optical pressure-sensitive coating are fixedly installed on the corresponding sides of the optical window, a camera lens is installed on the CCD camera, a narrow-band filter is installed in front of the camera lens for filtering out the excitation light of the LED light source; The LED light source is electrically connected with a digital signal generator through a second data transmission line, and the digital signal generator is used to send a pulse signal to control the LED light source to emit excitation light; The CCD camera is electrically connected with a computer through a first data transmission line, and the CCD camera sends the collected images to the computer; The collected images are the luminescence images of the optical pressure-sensitive coating on the wall surface of the compressor casing, and the pressure of the wall surface of the compressor casing corresponding to the luminescence images is obtained; The optical window is made of quartz glass to improve the transmittance of the excitation light of the optical pressure-sensitive coating; The optical pressure-sensitive coating is composed of a transparent primer and a luminescent finish, the transparent primer is first sprayed on the inner wall surface of the optical window, then the luminescent finish is sprayed on the transparent primer after baking, and then mark points for image registration are made on the luminescent finish for image registration; The excitation light of the LED light source first transmits through the optical window, then passes through the transparent primer, and finally reaches the luminescent finish, so as to realize the excitation of the optical pressure-sensitive coating; when the optical pressure-sensitive coating is excited, the emission light of the optical pressure-sensitive coating first transmits through the transparent primer, then transmits through the optical window, and finally is captured by the CCD camera, so as to realize the collection of the luminescence images of the optical pressure-sensitive coating; A phase-locked patch is also attached to the rotating shaft at the inlet of the compressor, a phase-locked sensor is arranged on the corresponding side of the phase-locked patch, the phase-locked sensor is electrically connected with an external trigger port of the digital signal generator through a third data transmission line, and the digital signal generator controls the LED light source to emit excitation light through the external trigger signal sent by the phase-locked sensor.

2. The sensitive paint window based compressor casing wall pressure measurement system as claimed in claim 1, wherein, The camera lens is installed on the CCD camera through an adapter ring.

3. The sensitive paint window based compressor casing wall pressure measurement system as claimed in claim 1, wherein, The bandwidth of the narrow-band filter is 650±15nm, and the peak wavelength band of the LED light source is 405±17nm.

4. The sensitive paint window based compressor casing wall pressure measurement system as claimed in claim 1, wherein, An optical platform is also provided, which is arranged at the optical window, and the CCD camera and the LED light source are fixedly installed on the optical platform.

5. The sensitive paint window based compressor case wall pressure measurement system as claimed in claim 1, wherein, The phase-locked sensor is fixed on a tripod at a position more than 2m away from the inlet of the compressor, and the phase-locked sensor is arranged opposite to the phase-locked patch; At the same time, the exposed area of the rotating shaft outside the phase-locked patch is blackened to ensure the normal triggering of the phase-locked patch.

6. A method of measurement as claimed in any one of claims 1 to 5, characterised in that, The measurement method is to collect the luminescence images of the optical pressure-sensitive coating to measure the transient pressure of the wall surface of the compressor casing after phase-locked by the phase-locked sensor, and the specific steps include: The running state of the compressor is taken as the actual working condition for measurement, and the actual working condition is as follows: Firstly, the LED light source is set to pulse mode, and the pulse width time of the light source is determined according to the tip speed of the blade in the actual working condition, and the pulse width time of the pulse signal for controlling the light emission of the LED light source is set on the digital signal generator; The pulse width time is the time when the light source emits light to irradiate the optical pressure sensitive coating at the same phase of the compressor rotor, and the image captured when the pulse width time is too long will be blurred; Secondly, the photoelectric phase-locked sensor emits laser light, and when the phase-locked patch sweeps across the laser light emitted by the phase-locked sensor, the photoelectric phase-locked sensor receives the reflected light signal of the phase-locked patch, and then converts the external trigger excitation signal into an external trigger excitation signal, and then transmits the external trigger excitation signal to the external trigger port of the digital signal generator as an external trigger signal for controlling the LED light source to pulse flash; Subsequently, the actual working condition light is turned off, and the LED light source is turned on to pulse excite the optical pressure sensitive coating, and the CCD camera continuously collects, and when the image gray value reaches 1 / 2~3 / 4 of the camera full well value, the exposure time of the CCD camera is determined to prevent overexposure; Finally, during the excitation of the optical pressure sensitive coating by the excitation light, the CCD camera works continuously, and the shutter is in an open state. Each time the optical pressure sensitive coating is excited by the excitation light, the CCD camera records the light emission image. After continuous pulse excitation of the optical pressure sensitive coating, the light emission images are continuously superimposed, and finally, the first light emission image of the compressor casing wall surface with high signal-to-noise ratio is obtained. The state of the compressor after shutdown is taken as the reference state for measurement, and in the reference state: First, the experimental environment light is turned off, the LED light source is turned on, the pulse width time is consistent with that of the actual working condition, the CCD camera is continuously collected, the exposure time is consistent with that of the actual working condition, the first reference image is obtained by shooting, and the corresponding compressor casing wall pressure is the atmospheric pressure in the experimental environment, which is recorded as the first windless pressure. P ref1 ; Then, the environmental light source and the LED light source are turned off, and the first dark background image is captured by the CCD camera; Finally, using the luminescence intensity of the first luminescence image and the luminescence intensity of the first reference image, the first intensity value of the first dark background image is subtracted, respectively I d1 ; Further, according to the pressure-light intensity calibration relationship obtained by calibration: ， wherein I ref1 is the first reference image luminous intensity minus the first intensity value I d1 ; I 1is the first luminous image luminous intensity minus the first intensity value I d1 ; T is the temperature of the optical window wall surface, A , B is the temperature coefficient, P 1is the first transient pressure of the compressor casing wall surface corresponding to the first luminous image.

7. The measurement method implemented by the compressor casing wall pressure measurement system based on a sensitive coating window as described in claim 6, characterized in that, Before the measurement method starts, the blade, the blade tip and the casing area around the optical window are sprayed with black paint.

8. A method of measuring as claimed in any one of claims 1 to 5, wherein the method is implemented by a sensitive paint window based compressor casing wall pressure measurement system, characterised in that, The measurement method is to obtain the circumferential average pressure distribution of the compressor casing wall surface by long-time exposure of the CCD camera to collect the light emission image of the optical pressure sensitive coating, including the following steps: The state of the compressor after shutdown is taken as the reference state for measurement, and in the reference state: Firstly, the exposure time of the CCD camera is determined to prevent overexposure; Then, the environmental light source and the LED light source are turned off, and the second dark background image is captured by the CCD camera; Finally, the LED light source is set to a constant light mode, and the CCD camera is set to a long exposure mode; subsequently, the optical pressure-sensitive paint is continuously excited using the excitation light emitted by the LED light source, and the second reference image is captured using the CCD camera, and the corresponding compressor casing wall surface pressure is the atmospheric pressure in the experimental environment, which is recorded as the second windless pressure P ref2 ; The running state of the compressor is taken as the actual working condition for measurement, and in the actual working condition: The LED light source is set to constant mode, and the CCD camera is set to long exposure mode, i.e. consistent with the setting in the reference state. The excitation light of the LED light source continuously excites the optical pressure sensitive coating, and the CCD camera captures the second light emission image; Finally, using the luminescence intensity of the second luminescence image and the luminescence intensity of the second reference image, the second intensity value of the second dark background image is subtracted, respectively I d2 ; Further, according to the pressure-light intensity calibration relationship obtained by calibration: ， wherein I ref2 is the second reference image luminance value, I d2 is the second reference image luminance value, I 2 is the second luminance value, I d2 2 is the second luminance value, T is the temperature of the optical window wall surface, A , B is the temperature coefficient, P 2 is the second circumferential average pressure of the compressor casing wall surface.

Images