Image acquisition system for tracking imaging of rotor blade

Abstract

The invention provides an image acquisition system for tracking imaging of a rotor blade. The image acquisition system comprises a light source tracking system, a high-speed imaging system and a synchronous control system, the light source tracking system comprises a light source tracking high-precision turntable, a light source tracking reflector group, a light source tracking protective cover and an excitation light source; the high-speed imaging system comprises an imaging high-precision turntable, an imaging reflector group, a high-speed imaging protective cover, a high-speed camera and a coaxial light splitting device; the synchronous control system comprises a photoelectric coded disc, a delay signal emitter and an image tracking correction plate. The device is reasonable in structural design, all-phase 2D temperature and pressure dynamic measurement of the surface of the rotor blade can be realized by combining the pressure-sensitive (PSP) / temperature-sensitive (TSP) coating, and image blurring can be eliminated, the signal-to-noise ratio of the image can be improved and high-precision temperature and pressure measurement results can be obtained under the condition of long exposure time based on the light source and the image tracking system of the high-speed rotating mirror.

Description

Technical Field

[0001] This invention relates to the field of dynamic image acquisition technology for high-speed moving objects, and specifically to an image acquisition system for rotor blade tracking imaging. Background Technology

[0002] Surface pressure measurement of helicopter rotor blades is crucial for blade structure and aerodynamic performance design. Traditional point measurement techniques measure blade surface pressure by placing miniature pressure sensors on the blade surface. However, point measurement sensors can only obtain single-point pressure values, resulting in insufficient spatial resolution. Furthermore, point measurement requires pre-drilling holes and slots on the blade, which not only compromises the blade's structural strength and frequency characteristics but also makes them prone to detachment during high-speed rotation, leading to test failure. Pressure-sensitive coating (PSP) technology is an optical, large-area pressure measurement technique. By spraying a pressure-sensitive coating (PSP) onto the blade surface and collecting changes in the coating's fluorescence lifetime or light intensity under excitation light conditions, the pressure change can be calculated. Compared to traditional point measurement methods, it offers advantages such as high spatial resolution and a large amount of information acquired.

[0003] Currently, methods for measuring blade surface pressure based on pulse-strain pressure (PSP) mainly fall into two categories: lifetime methods and light intensity methods. Light intensity-based PSP measurement technology has been widely used in transonic and supersonic flow fields. The experimental model is typically fixed within the experimental section, remaining stationary relative to the light source and camera. Precise timing control enables the measurement of dynamic pressure fields, obtaining time-resolved pressure distribution on the model wall. The other method is the lifetime method, which measures pressure distribution through luminescence lifetime. Compared to the light intensity method, the fluorescence lifetime-based method has a certain self-referencing characteristic, reducing measurement errors caused by non-uniform illumination. Therefore, it is commonly used for measuring wall pressure on dynamic models. However, since the lifetime method typically only obtains pressure distribution at a specific phase, it cannot meet the needs of dynamic rotor blade measurement. Therefore, developing light intensity-based testing technology for high-speed rotor blades is of great significance. Furthermore, to eliminate the temperature influence during PSP measurement, a two-component pressure-sensitive coating is usually required for simultaneous temperature and pressure measurement to achieve temperature correction.

[0004] Current PSP image acquisition systems for high-speed rotating blades typically employ high-power excitation light sources to illuminate and excite the entire or partial phase of the plane in which the blades move, in conjunction with a high-speed camera for direct image acquisition. However, this system is limited by exposure time and frame rate; high exposure times can easily lead to image blurring and make it difficult to achieve an ideal signal-to-noise ratio. Furthermore, high-power light sources require complex water-cooling systems to improve their stability, resulting in complex systems and high experimental costs. Therefore, this invention aims to design and develop a high-speed imaging system with both light source and image tracking capabilities to meet the dynamic measurement needs of high-speed rotor blades. Summary of the Invention

[0005] To address the technical problems existing in the background art, the present invention proposes an image acquisition system for rotor blade tracking imaging. Its structure is reasonably designed and can realize full-phase 2D dynamic measurement of temperature and pressure on the rotor blade surface. The light source and image tracking system based on the high-speed rotating mirror can eliminate image blurring under long exposure time conditions, improve the image signal-to-noise ratio, and obtain high-precision temperature and pressure measurement results.

[0006] To solve the above-mentioned technical problems, the present invention provides an image acquisition system for rotor blade tracking imaging, which includes a light source tracking system, a high-speed imaging system and a synchronization control system;

[0007] The light source tracking system is installed on one side of the rotor blade and includes a high-precision turntable for light source tracking, a group of light source tracking reflectors, a protective cover for light source tracking, and an excitation light source. The protective cover for light source tracking is fitted onto the high-precision turntable for light source tracking and covers the group of light source tracking reflectors. The excitation light source is fitted onto the inner top of the protective cover for light source tracking. The group of light source tracking reflectors is fitted and fixed to the upper part of the high-precision turntable for light source tracking and is rotated by the high-precision turntable for light source tracking to irradiate the coating area of ​​the high-speed rotating rotor blade with the excitation light from the excitation light source. The continuous excitation of the coating on the surface of the rotor blade is achieved by tracking the rotor blade with the light source.

[0008] The high-speed imaging system is matched and installed on one side of the light source tracking system. It includes a high-precision imaging turntable, an imaging mirror assembly, a high-speed imaging protective cover, a high-speed camera, and a coaxial beam splitter. The imaging mirror assembly is matched and installed on the upper part of the high-precision imaging turntable, and is driven by the high-precision imaging turntable to rotate at high speed to achieve tracking imaging of the rotor blades. The high-speed imaging protective cover is matched and installed on the upper part of the high-precision imaging turntable and covers the imaging mirror assembly. The coaxial beam splitter is matched and installed in the high-speed imaging protective cover and is used to split the reflected light of different wavelengths from the imaging mirror assembly. The high-speed camera is matched and installed inside the high-speed imaging protective cover and is used to acquire fluorescence intensity images of the pressure-sensitive or temperature-sensitive components on the rotor blade surface in the corresponding bands.

[0009] The synchronous control system includes an optoelectronic encoder, a delay signal transmitter, and an image tracking correction board. The optoelectronic encoder is installed at the bottom of the central shaft of the rotor platform, while the image tracking correction board and the delay signal transmitter are located in the main control room of the rotor platform. When the rotor blades rotate, the optoelectronic encoder provides an initial phase signal through zero-position triggering and triggers the delay signal transmitter. The delay signal transmitter controls the rotation of the light source tracking high-precision turntable and the imaging high-precision turntable and the synchronous acquisition by the high-speed camera. The image tracking correction board outputs a correction signal through the imaging of the high-speed camera to achieve rotational speed correction of the light source tracking high-precision turntable and the imaging high-precision turntable.

[0010] The image acquisition system for rotor blade tracking imaging includes: a high-precision turntable for light source tracking, comprising a light source tracking turntable and a light source tracking servo motor, a light source tracking controller, and a light source tracking driver that are matched and installed inside the light source tracking turntable;

[0011] The light source tracking controller is electrically connected to the light source tracking driver; the light source tracking driver is electrically connected to the light source tracking servo motor; the power output terminal of the light source tracking servo motor is matched and connected to the light source tracking turntable to drive the light source tracking turntable to rotate; the light source tracking protective cover is matched and installed on the upper part of the light source tracking turntable.

[0012] The light source tracking controller is triggered by the photoelectric encoder when the rotor blades move, and then drives the light source tracking servo motor to move through the light source tracking driver, so as to realize the synchronization of the light source tracking turntable with the rotor blade speed, and the speed range covers the rotor blade rotation range of 0 r / min to 1050 r / min; the speed of the light source tracking turntable is corrected in real time by the signal of the image tracking correction board.

[0013] The image acquisition system for rotor blade tracking imaging includes: the light source tracking reflector group consists of a first light source tracking reflector facing the rotor blade and a second light source tracking reflector facing the excitation light source; both the first and second light source tracking reflectors are single-wavelength dielectric film high-reflectivity mirrors or ultraviolet mirrors selected according to the wavelength of the excitation light source; the distance and angle between the first and second light source tracking reflectors are adjusted according to the diameter of the rotor blade and the shooting distance.

[0014] The image acquisition system for rotor blade tracking imaging includes an LED excitation source that is either ultraviolet or blue light, with a center wavelength of 365nm, 395nm, 405nm, or 455nm, and the power of the light source is adjustable from 0 to 100W according to experimental requirements.

[0015] The image acquisition system for rotor blade tracking imaging includes: a high-precision imaging turntable comprising an imaging turntable and an imaging servo motor, an imaging controller, and an imaging driver disposed inside the imaging turntable; the imaging controller is electrically connected to the imaging driver; the imaging driver is electrically connected to the imaging servo motor; the power output end of the imaging servo motor is matched and connected to the imaging turntable; a high-speed imaging protective cover is matched and installed on the upper part of the imaging turntable; the imaging turntable, driven by the imaging servo motor, the imaging controller, and the imaging driver, achieves synchronization with the rotor blade rotation speed, with a rotation speed range covering 0 r / min-1050 r / min; the rotation speed of the imaging turntable is corrected in real time by the signal from the image tracking correction plate.

[0016] The image acquisition system for rotor blade tracking imaging includes: a coaxial beam splitter composed of a dichroic beam splitter crystal combining a conventional non-polarizing beam splitter and dichroic beam splitting film technology; the dichroic beam splitter crystal is installed in a cage system, and the excitation light from the LED excitation source is cut off by the dichroic beam splitter crystal; the transmitted light and reflected light separated from the dichroic beam splitter crystal are the fluorescence emitted by the single-component coating or the two-component coating, respectively; the wavelength of the dichroic beam splitter crystal is customized according to the emission wavelength of the pressure-sensitive and temperature-sensitive coatings.

[0017] The image acquisition system for rotor blade tracking imaging includes: the imaging mirror group consists of a first imaging mirror facing the rotor blade and a second imaging mirror facing the dichroic beam-splitting crystal; both the first and second imaging mirrors are single-wavelength dielectric film high-reflectivity mirrors, with the wavelength selected according to the emission wavelength of the pressure-sensitive / temperature-sensitive coating, and the center wavelength being any one or two of 520nm, 580nm, 600nm, and 650nm; the full-phase image acquisition of the rotor blade is achieved by adjusting the distance and angle between the first and second imaging mirrors.

[0018] The image acquisition system for rotor blade tracking imaging includes: one high-speed camera with a single-component coating and single-wavelength emission, or two high-speed cameras with a dual-component coating and dual-wavelength emission. When using a dual-component coating, the two high-speed cameras are arranged at 90° on both sides of the transmitted light and reflected light of the dichroic beam splitter crystal, with one camera collecting the reflected light and the other collecting the transmitted light.

[0019] The image acquisition system for rotor blade tracking imaging includes a high-speed camera equipped with a fixed-focus lens; the fixed-focus lens has a focal length of 25mm, 50mm, 85mm or 100mm and an aperture size greater than f1.4.

[0020] The image acquisition system for rotor blade tracking imaging includes a high-speed camera equipped with a filter of a corresponding wavelength. The filter is a narrow-band interference filter with a wavelength range of 500nm–540nm, 580nm–620nm, or 630nm–670nm. The wavelengths of the filter correspond to the pressure measurement channel and the temperature measurement channel, respectively, enabling separate measurement of pressure or temperature, as well as simultaneous measurement of temperature and pressure.

[0021] By adopting the above technical solution, the present invention has the following beneficial effects:

[0022] The image acquisition system for rotor blade tracking imaging of this invention has a reasonable structural design. By combining pressure-sensitive (PSP) and temperature-sensitive (TSP) coatings, it can realize full-phase 2D dynamic measurement of temperature and pressure on the rotor blade surface. The light source and image tracking system based on a high-speed rotating mirror can eliminate image blurring under long exposure time conditions, improve the image signal-to-noise ratio, and obtain high-precision temperature and pressure measurement results.

[0023] This invention combines an excitation light source and a high-speed imaging system with a high-speed rotating mirror system, so that the excitation light source is directed to illuminate a high-speed rotating rotor blade coated with a pressure-sensitive (PSP) / temperature-sensitive (TSP) coating. Then, the high-speed camera synchronously collects the changes in the fluorescence intensity of the coating. With the help of an optoelectronic encoder and an image tracking correction plate, the imaging effect is evaluated and the rotation speed is corrected, so as to realize the synchronous acquisition of pressure and temperature on the rotor blade surface.

[0024] In this invention, the excitation source of the LED excitation source combined with the rotating mirror system can track and excite the blade locally, overcoming the shortcomings of current high-power light sources such as high cost, system complexity, and poor stability. By changing the intensity, angle, and wavelength of the light source, the system has better scalability. The beam splitting system using a dichroic beam splitting crystal can select a specific wavelength while splitting the beam, reducing the waste of beam signal and the loss of light intensity. The image correction combined with the high-speed rotating mirror system and the image tracking correction board enables the high-speed camera to acquire data at high exposure times, avoiding the image blurring problem caused by excessive exposure time in traditional direct shooting. At the same time, the synchronous acquisition of dual cameras also reduces image registration errors, achieving high-precision synchronous acquisition of temperature and pressure, and improving measurement accuracy. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is an overall schematic diagram of the image acquisition system for rotor blade tracking imaging according to the present invention;

[0027] Figure 2 This is a schematic diagram of the light source tracking system of the image acquisition system for rotor blade tracking imaging of the present invention;

[0028] Figure 3 This is a schematic diagram of the high-speed imaging system of the image acquisition system for rotor blade tracking imaging of the present invention;

[0029] Figure 4 The present invention relates to an image acquisition system for rotor blade tracking and imaging, which includes a rotor blade coated with a pressure-sensitive coating and an image under excitation light.

[0030] Figure 5 This is a grayscale image acquired during a rotor blade test related to the image acquisition system for rotor blade tracking imaging of the present invention.

[0031] Figure 6 This is a schematic diagram of the two-component coating spectral analysis involved in the image acquisition system for rotor blade tracking imaging of the present invention. Detailed Implementation

[0032] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The present invention will be further explained below with reference to specific embodiments.

[0034] like Figure 1 As shown in the figure, this embodiment provides an image acquisition system for rotor blade tracking imaging, which includes a light source tracking system 1, a high-speed imaging system 2, and a synchronization control system 3.

[0035] The light source tracking system 1 includes a high-precision turntable 11 for light source tracking, a first light source tracking reflector 12, a second light source tracking reflector 13, a light source tracking protective cover 14, and an excitation light source 15.

[0036] The high-precision light source tracking turntable 11 is mounted on one side of the rotor blade 4. It includes the light source tracking turntable 111 and a light source tracking servo motor, a light source tracking controller, and a light source tracking driver, all matched and installed inside the turntable. The light source tracking controller is electrically connected to the light source tracking driver, which in turn is electrically connected to the light source tracking servo motor. The power output of the light source tracking servo motor is matched and connected to the turntable 111 to drive its rotation. The light source tracking controller is triggered by the photoelectric encoder 31 of the synchronization control system 3 during rotor blade 4 movement, which in turn drives the light source tracking servo motor via the light source tracking driver. This achieves synchronization between the light source tracking turntable 111 and the rotor blade 4, with the rotational speed covering the range of 0 r / min to 1050 r / min. The rotational speed of the light source tracking turntable 111 can be corrected in real time using signals from the image tracking correction board 32 of the synchronization control system 3.

[0037] The light source tracking reflector assembly is fixed to the upper center of the light source tracking turntable 111, driven by the high-precision turntable 111 to rotate, so as to irradiate the coating area of ​​the high-speed rotating rotor blade 4 with the excitation light from the excitation light source 15. Continuous excitation of the coating on the surface of the rotor blade 4 is achieved by tracking the rotor blade 4 with the light source. The light source tracking reflector assembly consists of a first light source tracking reflector 12 facing the rotor blade 4 and a second light source tracking reflector 13 facing the excitation light source 15. Both the first light source tracking reflector 12 and the second light source tracking reflector 13 are single-wavelength dielectric film high-reflectivity mirrors or ultraviolet reflectors, which can be selected according to the wavelength of the excitation light source 15. The distance and angle between the first light source tracking reflector 12 and the second light source tracking reflector 13 can be adjusted according to the diameter of the rotor blade 4 and the shooting distance.

[0038] The light source tracking protective cover 14 is fitted over the light source tracking turntable 111 of the high-precision light source tracking turntable 11, and covers the first light source tracking reflector 12 and the second light source tracking reflector 13 within it.

[0039] The excitation light source 15 is matched and set on the inner top of the light source tracking protective cover 14. It adopts an LED excitation light source and can be an ultraviolet or blue light source. The center wavelength of the light source can be 365nm, 395nm, 405nm or 455nm. The power of the light source can be adjusted in the range of 0 to 100W according to the test requirements.

[0040] The first light source tracking reflector 12, the second light source tracking reflector 13, and the excitation light source 15 are integrated in the light source tracking protective cover 14. The high-precision turntable 11 for light source tracking drives the light source tracking reflector group to rotate, so that the excitation light from the excitation light source 15 is irradiated on the coating area of ​​the high-speed rotating rotor blade 4. The continuous excitation of the coating on the surface of the rotor blade 4 is achieved through light source tracking.

[0041] The high-speed imaging system 2 includes a high-precision imaging turntable 21, a first imaging mirror 22, a second imaging mirror 23, a high-speed imaging protective cover 24, a first high-speed camera 25, a second high-speed camera 26, a fixed-focus lens 27, a filter 28, and a dichroic beam splitter 29.

[0042] The high-precision imaging turntable 21 includes an imaging turntable 211 and an imaging servo motor, an imaging controller, and an imaging driver disposed inside the imaging turntable 211. The imaging controller is electrically connected to the imaging driver, and the imaging driver is electrically connected to the imaging servo motor. The power output end of the imaging servo motor is matched and connected to the imaging turntable 211 to drive the imaging turntable 211 to rotate. The imaging turntable 211 is driven by the imaging servo motor, the imaging controller, the imaging driver, and the imaging turntable 211 itself, achieving synchronization with the rotational speed of the rotor blade 4, with a rotational speed range covering 0 r / min-1050 r / min. The rotational speed of the imaging turntable 211 can be corrected in real time by the image tracking correction board 32 of the synchronization control system 3.

[0043] The imaging mirror assembly is matched and positioned at the center of the upper part of the imaging turntable 211 of the high-precision imaging turntable 21. The high-precision imaging turntable 21 drives it to rotate at high speed to achieve tracking imaging of the rotor blade 4. The imaging mirror assembly consists of a first imaging mirror 22 facing the rotor blade 4 and a second imaging mirror 23 facing the dichroic beam splitter 29. Both the first imaging mirror 22 and the second imaging mirror 23 are single-wavelength dielectric film high reflectivity mirrors. The wavelength is selected according to the emission wavelength of the pressure-sensitive (PSP) / temperature-sensitive (TSP) coating 6. The center wavelength can be one or two of 520nm, 580nm, 600nm, and 650nm. By adjusting the distance and angle between the first imaging mirror 22 and the second imaging mirror 23, the full-phase image acquisition of the rotor blade 4 can be achieved.

[0044] The coaxial beam splitter is matched and installed inside the high-speed imaging protective cover 24 to achieve beam splitting of reflected light of different wavelengths from the imaging mirror group. It is composed of a dichroic beam splitter 29, which combines a conventional non-polarizing beam splitter with dichroic beam splitting film technology. The dichroic beam splitter 29 is installed in a cage system (a metal frame for fixing square crystals or other optical devices, which can be modularly assembled). The excitation light (emitted by the LED excitation light source) of the excitation source is cut off by the dichroic beam splitter 29. The transmitted light and reflected light split from the dichroic beam splitter 29 can be fluorescence of a single-component coating or a two-component coating, respectively (the transmitted light and reflected light correspond to one component and are two different wavelengths of light. When the coating is two-component, they correspond to the light of the temperature and pressure channels, respectively. When the coating is single-component, they correspond to one type of light). The wavelength of the dichroic beam splitter 29 can be customized according to the emission wavelength of the pressure-sensitive (PSP) and temperature-sensitive (TSP) coatings 6.

[0045] The high-speed imaging protective cover 24 is fitted over the imaging turntable 211 of the high-precision imaging turntable 21, and houses the high-speed camera within it. The high-speed camera is internally housed within the high-speed imaging protective cover 24. This high-speed camera is used to acquire fluorescence intensity images of the pressure-sensitive or temperature-sensitive components on the blade surface in corresponding wavelengths. The high-speed camera is equipped with a fixed-focus lens 27. The focal length of the fixed-focus lens 27 can be 25mm, 50mm, 85mm, or 100mm, and the lens aperture is greater than f / 1.4 to ensure a good signal-to-noise ratio. In this embodiment, the high-speed camera employs a dual-component coating and dual-wavelength emission, and includes a first high-speed camera 25 positioned laterally inside the high-speed imaging protective cover 24 and a second high-speed camera 26 positioned at the top inside the high-speed imaging protective cover 24. Specifically, the first high-speed camera 25 and the second high-speed camera 26 are arranged at a 90° angle to the transmitted light side of the dichroic beam-splitting crystal 29.

[0046] This high-speed camera has a resolution exceeding 1920*1080 and a full-frame frame rate greater than 2000fps. It is also equipped with a filter 28 of corresponding wavelengths. The filter 28 is a narrowband interference filter with a wavelength range of 500nm~540nm, 580nm~620nm, or 630nm~670nm. The wavelengths of the filter 28 correspond to the pressure measurement channel and the temperature measurement channel, respectively, which can realize the separate measurement of temperature or the simultaneous measurement of temperature and pressure.

[0047] The high-speed camera is equipped with a fixed-focus lens 27 and a filter 28 of the corresponding wavelength. The dichroic beam splitter 29 is integrated into the cage system, which can realize beam splitting of different wavelengths. The imaging mirror group is set on the imaging turntable 211. The imaging turntable 211 drives the imaging mirror group to rotate at high speed to realize the tracking imaging of the rotor blade 4.

[0048] The synchronous control system 3 includes an optoelectronic encoder 31, an image tracking correction board 32, and a delay signal transmitter. The optoelectronic encoder 31 is installed at the bottom of the central shaft of the rotor platform, while the image tracking correction board 32 and the delay signal transmitter are located in the main control room of the rotor platform. When the rotor blades 4 rotate, the optoelectronic encoder 31 provides an initial phase signal through zero-position triggering and triggers the delay signal transmitter. The delay signal transmitter controls the rotation of the high-precision light source tracking turntable 11 and the high-precision imaging turntable 21 and the synchronous acquisition by the high-speed camera. The image tracking correction board 32 corrects the rotation speed of the high-precision light source tracking turntable 11 and the high-precision imaging turntable 21 by outputting correction signals through the imaging of the high-speed camera. The photoelectric encoder 31 of the synchronous control system 3 can provide an initial phase signal for the image acquisition system of the present invention through zero-position triggering. The encoder hole position of the photoelectric encoder 31 corresponding to the azimuth angle of the rotor blade 4 is selected, and the measurement position is aligned with the trailing edge position of the rotor blade 4. Each time the rotor blade 4 rotates once, the encoder hole position of the designated photoelectric encoder 31 can receive a signal once and synchronously output a TTL signal to trigger the delay signal generator 32. The delay signal generator 32 can be used as a trigger for the high-speed camera and the excitation light source 15. After receiving the photoelectric encoder signal, the delay signal generator 32 outputs a 5V TTL signal to trigger the excitation light source 15 and the first high-speed camera 25 and the second high-speed camera 26 to acquire data synchronously. The synchronous tracking correction board 32 can identify and track the rotor blade 4 according to the high-definition image SDI signal acquired by the high-speed camera, and adjust the rotation speed of the light source tracking high-precision turntable 11 of the light source tracking system 1 and the imaging high-precision turntable 21 of the high-speed imaging system 2 through the correction signal to ensure the tracking and shooting of the rotor blade 4.

[0049] The invention will be further illustrated below with specific examples of rotor blade surface pressure measurement experiments.

[0050] Example 1

[0051] An image acquisition system used for rotor blade tracking imaging in this invention was used to conduct a test measuring the surface pressure of rotor blade 4 based on pressure-sensitive coating (PSP) technology. The test system is as follows: Figure 1 As shown, before the experiment, a pressure-sensitive coating was first sprayed onto the surface of the rotor blade 4. The coating was dried at room temperature in the dark for 12 hours. The rotor blade 4 with the pressure-sensitive coating was then installed on the rotor platform along with other blades. Based on the distance between the plane of the rotor blade 4 and the image acquisition system for rotor blade tracking imaging of this invention, and the size of the rotor blade 4, the light source tracking system 1 (e.g., Figure 2 ) and high-speed image acquisition system 2 (such as Figure 3The reflector group of the excitation light source 15 is adjusted to ensure that the area illuminated by the excitation light source 15 and the area acquired by the high-speed camera covers the coating area of ​​the rotor blade 4. During the experiment, the azimuth angle of the rotor blade 4 is aligned with the starting position of the photoelectric encoder disk 31 at 0°, and the measurement position is strictly aligned with the trailing edge of the rotor blade 4. During the rotation, the encoder disk 31 receives the signal through the encoder hole and triggers the delay signal generator 32. The delay signal generator 32 then controls the rotation of the excitation light source 15, the high-speed camera, the light source tracking high-precision turntable 11, and the imaging high-precision turntable 21, realizing the dynamic image acquisition during the movement of the rotor blade 4. After each rotation, the image tracking correction plate 32 identifies the image acquired by the high-speed camera and outputs a correction signal to correct the rotation speed of the light source tracking high-precision turntable 11 and the imaging high-precision turntable 21. Finally, the dynamic pressure distribution result of the rotor blade 4 in all phases is obtained. During the experiment, the rotor blade 4 coated with the pressure-sensitive coating and its fluorescence imaging under the excitation light are shown in the figure. Figure 4 As shown.

[0052] Example 2

[0053] Unlike Example 1, another embodiment of the present invention compares the imaging effects of surface pressure measurement on rotor blade 4 using different image acquisition methods. The rotor blade 4 has a diameter of Φ800mm and a tip velocity of 90m / s. A pressure-sensitive coating is sprayed onto the surface of the rotor blade 4, and after drying at room temperature in the dark to form a pressure-sensitive coating, the rotor blade 4 is mounted on a rotor platform. The image acquisition system of the present invention (e.g., Figure 1 Pressure measurements were conducted on the surface of rotor blade 4, with the experimental setup consistent with Example 1, and the high-speed camera exposure time was 20 μs. Alternatively, a traditional image acquisition method using large-area excitation and direct imaging was employed. A combination of high-power LED excitation light sources was used, with the excitation light source 15 covering the entire surface of rotor blade 4. During the experiment, the signal output from the photoelectric encoder 31 triggered the delay signal generator 32, which in turn triggered the high-speed camera for acquisition. To ensure the signal-to-noise ratio of the acquired image, the high-speed camera exposure time was 20 μs. The grayscale images of rotor blade 4 acquired during the experiment are shown below. Figure 5 As shown, images captured directly using large-area excitation suffer from significant blurring under long exposure times. However, the image acquisition system described in this invention, which employs light source and image tracking, maintains clear edges and a high signal-to-noise ratio even under long exposure times.

[0054] Example 3

[0055] Unlike Examples 1 and 2, Example 3 utilizes the image acquisition system of this invention to conduct a surface pressure measurement experiment on a rotor blade 4 based on a two-component pressure-sensitive coating. The rotor blade 4 has a diameter of 4 m and a tip velocity of approximately 220 m / s. A two-component pressure-sensitive coating is sprayed onto the surface of the rotor blade 4 and dried at room temperature in the dark to form a two-component pressure-sensitive coating. The rotor blade 4 is mounted on a rotor platform. The high-speed imaging system 2 employs dual high-speed cameras. Based on the fluorescence spectral characteristics of the two-component coating, the two wavelengths of the dichroic spectrophotometer are 525 nm for the temperature-sensitive channel and 650 nm for the pressure-sensitive channel. The high-speed cameras are equipped with narrowband filters of 525 nm-40 nm and 600 nm-40 nm, respectively, to achieve synchronous acquisition of surface temperature and pressure channel light intensity changes of the rotor blade 4. The spectrophotometer spectral characteristics are as follows: Figure 6 As shown.

[0056] This invention enables full-phase 2D dynamic measurement of temperature and pressure on rotor blade surfaces. The light source and image tracking system based on a high-speed rotating mirror can eliminate image blurring under long exposure time conditions, improve the image signal-to-noise ratio, and obtain high-precision temperature and pressure measurement results.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An image acquisition system for rotor blade tracking imaging, characterized in that... The image acquisition system includes a light source tracking system (1), a high-speed imaging system (2), and a synchronous control system (3); The light source tracking system (1) is set on one side of the rotor blade (4), and includes a high-precision turntable (11) for light source tracking, a light source tracking reflector group, a light source tracking protective cover (14) and an excitation light source (15). The light source tracking protective cover (14) is matched and covered on the high-precision turntable (11) for light source tracking and covers the light source tracking reflector group. The excitation light source (15) is matched and set on the inner top of the light source tracking protective cover (14). The light source tracking reflector group is matched and fixed on the upper part of the high-precision turntable (11) for light source tracking. The high-precision turntable (11) drives it to rotate so that the excitation light of the excitation light source (15) irradiates the coating area of ​​the high-speed rotating rotor blade (4). The continuous excitation of the coating on the surface of the rotor blade (4) is achieved by tracking the rotor blade (4) with the light source. The high-speed imaging system (2) is matched and installed on one side of the light source tracking system (1). It includes a high-precision imaging turntable (21), an imaging mirror group, a high-speed imaging protective cover (24), a high-speed camera, and a coaxial beam splitter. The imaging mirror group is matched and installed on the upper part of the high-precision imaging turntable (21). The high-precision imaging turntable (21) drives the high-speed rotation of the mirror group to achieve high-speed tracking imaging of the rotor blade (4). The high-speed imaging protective cover (24) is matched and installed on the upper part of the high-precision imaging turntable (21) and covers the imaging mirror group. The coaxial beam splitter is matched and installed in the high-speed imaging protective cover (24) and is used to split the reflected light of different wavelengths of the imaging mirror group. The high-speed camera is matched and installed inside the high-speed imaging protective cover (24) and is used to acquire fluorescence intensity images of the pressure-sensitive component or temperature-sensitive component on the surface of the rotor blade (4) in the corresponding band. The synchronous control system (3) includes an optoelectronic encoder (31), a delay signal transmitter, and an image tracking correction board (32). The optoelectronic encoder (31) is installed at the bottom of the central shaft of the rotor platform, while the image tracking correction board (32) and the delay signal transmitter are located in the main control room of the rotor platform. When the rotor blade (4) rotates, the optoelectronic encoder (31) provides an initial phase signal through zero-position triggering and triggers the delay signal transmitter. The delay signal transmitter controls the rotation of the light source tracking high-precision turntable (11) and the imaging high-precision turntable (21) and synchronously acquires data from the high-speed camera. The image tracking correction board (32) outputs a correction signal through the imaging of the high-speed camera to achieve rotational speed correction of the light source tracking high-precision turntable (11) and the imaging high-precision turntable (21).

2. The image acquisition system for rotor blade tracking imaging as described in claim 1, characterized in that: The high-precision turntable (11) for light source tracking includes a light source tracking turntable (111) and a light source tracking servo motor, a light source tracking controller and a light source tracking driver that are matched and set inside the light source tracking turntable (111); The light source tracking controller is electrically connected to the light source tracking driver; The light source tracking driver is electrically connected to the light source tracking servo motor; The power output end of the light source tracking servo motor is matched and connected to the light source tracking turntable (111) to drive the light source tracking turntable (111) to rotate; the light source tracking protective cover (14) is matched and covered on the upper part of the light source tracking turntable (111); The light source tracking controller is triggered by the photoelectric encoder (31) when the rotor blade (4) moves, and then drives the light source tracking servo motor to move through the light source tracking driver, so as to realize the synchronization of the rotation speed of the light source tracking turntable (111) with the rotor blade (4), and the rotation speed range covers the rotation range of the rotor blade (4) from 0 r / min to 1050 r / min; the rotation speed of the light source tracking turntable (111) is corrected in real time by the signal of the image tracking correction board (32).

3. The image acquisition system for rotor blade tracking imaging as described in claim 1, characterized in that: The light source tracking reflector group consists of a first light source tracking reflector (12) facing the rotor blade (4) and a second light source tracking reflector (13) facing the excitation light source (15); The first light source tracking mirror (12) and the second light source tracking mirror (13) are both single-wavelength dielectric film high reflectivity mirrors or ultraviolet reflectors selected according to the wavelength of the excitation light source (15); The distance and angle between the first light source tracking reflector (12) and the second light source tracking reflector (13) are adjusted according to the diameter of the rotor blade (4) and the shooting distance.

4. The image acquisition system for rotor blade tracking imaging as described in claim 1, characterized in that: The excitation light source (15) is an LED excitation light source and is an ultraviolet or blue light source. The center wavelength of the light source is 365nm, 395nm, 405nm or 455nm. The power of the light source can be adjusted in the range of 0 to 100W according to the test requirements.

5. The image acquisition system for rotor blade tracking imaging as described in claim 1, characterized in that: The high-precision imaging turntable (21) includes an imaging turntable (211) and an imaging servo motor, an imaging controller and an imaging driver disposed inside the imaging turntable (211); The imaging controller is electrically connected to the imaging driver; the imaging driver is electrically connected to the imaging servo motor; the power output end of the imaging servo motor is matched and connected to the imaging turntable (111); the high-speed imaging protective cover (24) is matched and installed on the upper part of the imaging turntable (211); The imaging turntable (2111) is driven by the imaging servo motor, imaging controller and imaging driver to achieve synchronization with the rotor blade (4) speed, with a speed range of 0 r / min-1050 r / min; the speed of the imaging turntable (211) is corrected in real time by the image tracking correction plate signal.

6. The image acquisition system for rotor blade tracking imaging as described in claim 1, characterized in that: The coaxial beam splitter is composed of a dichroic beam splitter crystal (29) that combines a conventional non-polarizing beam splitter with dichroic beam splitting film technology; The dichroic beam splitter (29) is installed in the cage system. The excitation light of the LED excitation light source is cut off by the dichroic beam splitter (29). The transmitted light and reflected light separated from the dichroic beam splitter are the fluorescence emitted by the single-component coating or the two-component coating, respectively. The wavelength of the dichroic spectrophotometer (29) is customized according to the emission wavelength of the pressure-sensitive and temperature-sensitive coating (6).

7. The image acquisition system for rotor blade tracking imaging as described in claim 6, characterized in that: The imaging mirror assembly consists of a first imaging mirror (22) facing the rotor blade (4) and a second imaging mirror (23) facing the dichroic beam-splitting crystal (29); The first imaging mirror (22) and the second imaging mirror (23) are both single-wavelength dielectric film high reflectivity mirrors. The wavelength is selected according to the emission wavelength of the pressure-sensitive / temperature-sensitive coating (6). The center wavelength is any one or two of 520nm, 580nm, 600nm and 650nm. The full-phase image acquisition of the rotor blade (4) is achieved by adjusting the distance and angle between the first imaging mirror (22) and the second imaging mirror (23).

8. The image acquisition system for rotor blade tracking imaging as described in claim 7, characterized in that: The high-speed camera is one with a single-component coating and single-wavelength emission, or two with a dual-component coating and dual-wavelength emission. When the dual-component coating is used, the two high-speed cameras are arranged at 90° on both sides of the transmitted light and reflected light of the dichroic beam splitter (29), with one camera collecting the reflected light and the other collecting the transmitted light.

9. The image acquisition system for rotor blade tracking imaging as described in claim 1, characterized in that: The high-speed camera is equipped with a fixed-focus lens (27); the fixed-focus lens (27) has a focal length of 25mm, 50mm, 85mm or 100mm and an aperture size greater than f1.

4.

10. The image acquisition system for rotor blade tracking imaging as described in claim 1, characterized in that: The high-speed camera is also equipped with a filter (28) of the corresponding wavelength; The filter (28) is a narrowband interference filter with a wavelength range of 500nm~540nm, 580nm~620nm or 630nm~670nm; The wavelengths of the filter (28) correspond to the pressure measurement channel and the temperature measurement channel, respectively, which can realize the individual measurement of pressure or temperature, or the simultaneous measurement of temperature and pressure.

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