A synchronous measurement system for surface deformation and pressure distribution of rotating parts

Abstract

The present invention relates to the technical field of measuring the surface deformation and pressure distribution of rotating parts, and in particular to a synchronous measurement system for the surface deformation and pressure distribution of rotating parts. The system includes a laser light source module, an image acquisition module, a synchronous control module and a rotating part carrier; the laser light source module is a laser light source capable of outputting a pulse width of 10ns; the image acquisition module includes two cross-frame CCD cameras, and the two cross-frame CCD cameras acquire two images within a set time interval; the synchronous control module is used to provide a trigger signal of the laser light source module and an acquisition signal of the image acquisition module; the rotating part carrier includes a rotating part to be measured, and the surface of the rotating part to be measured is provided with PSP coating and is arranged with speckle marking points. The system effectively controls the motion blur of the rotating part, making the image clearly visible; and realizes the phase locking of the high-speed rotating part.

Description

Technical Field

[0001] The invention relates to the technical field of rotating component surface deformation and pressure distribution measurement, and in particular to a rotating component surface deformation and pressure distribution synchronous measurement system. Background Art

[0002] Rotating machinery such as helicopter rotors, air and underwater propellers, compressor rotors and turbine blades are widely used in the aerospace field as important components of power propulsion systems. These components are characterized by high rotation speeds, and their surface pressure distribution and deformation are parameters of great concern overall, but traditional measurement methods are difficult to apply to the surface and space field measurements of such moving and rotating bodies, and there is a lack of intuitive and effective measurement methods for the multi-physical parameters of complex flow fields of rotating machinery.

[0003] The three-dimensional digital speckle correlation method (3D-DSCM) is an optical measurement technology used to measure the vibration of the model surface. DSCM, also known as the digital image correlation method (DIC), is a new optical measurement method based on the grayscale feature analysis of the speckle image on the surface of the object to obtain the object's motion and deformation information. Compared with traditional optical measurement technology, it has the advantages of full-field measurement, non-contact, high precision, relatively simple optical path, adjustable measurement field of view, and no special requirements for the measurement environment. However, since it only uses a single camera, it only obtains the two-dimensional (in-plane) displacement information of the plane object. The 3D-DSCM that combines binocular vision technology with DSCM has the advantages of being able to measure the three-dimensional morphology of the surface of a plane or curved model and the three-dimensional deformation under load. The process is to use two cameras to image the surface of the object to be measured from different angles. First, the two cameras are calibrated to obtain the internal and external parameters of the camera, and then the correlation matching algorithm in DSCM is directly used to obtain the parallax of the corresponding points in the left and right images. The three-dimensional morphology of the object surface is restored from the parallax data and calibration parameters of each point, and the three-dimensional displacement distribution of the entire field is obtained by comparing the three-dimensional morphology changes of each point in the measurement area before and after deformation.

[0004] PSP is a kind of pressure-sensitive coating developed in the 1980s based on luminescent oxygen quenching to measure surface pressure. It uses the emission of fluorescence by the coating after being irradiated with light of a certain wavelength. The intensity field of the emitted light is measured and the corresponding pressure distribution can be calculated. Compared with the conventional pressure measuring hole method, pressure sensitive paint pressure measurement can provide pressure distribution on the entire model surface without interfering with the flow field; it can capture detailed flow characteristics of complex flows; it can provide pressure distribution on small-sized models and thin wing surfaces that pressure measuring holes cannot provide; it does not need to manufacture models with many pressure measuring holes, and can be carried out simultaneously with many conventional measurement experiments. Summary of the invention

[0005] The object of the present invention is to provide a synchronous measurement system for the surface deformation and pressure distribution of a rotating component, which can solve the problem of measuring the surface deformation and pressure of the rotating component;

[0006] The present invention provides a synchronous measurement system for the surface deformation and pressure distribution of a rotating component, which comprises a laser light source module, an image acquisition module, a synchronous control module and a rotating component carrier;

[0007] The laser light source module is a laser light source capable of outputting a pulse width of 10ns;

[0008] The image acquisition module includes two cross-frame CCD cameras, which acquire two images within a set time interval;

[0009] The synchronization control module is used to provide a trigger signal for the laser light source module and a collection signal for the image collection module;

[0010] The rotating component carrier comprises a rotating component to be measured, and a surface of the rotating component to be measured is provided with PSP paint and is arranged with speckle marking points.

[0011] Preferably, the laser light source module comprises a laser light source and a conical light source, and the conical light source is arranged at the front end of the laser light source.

[0012] Preferably, the laser light source adopts a 532nm single-pulse laser with a single-pulse pulse width of 10ns±2ns;

[0013] When the irradiation area A is greater than 0.25m 2 When the single pulse energy is required to be ≥500mJ;

[0014] If a 532nm dual-cavity pulse laser is used, there is no need to trigger the second cavity pulse.

[0015] Preferably, the equivalent focal length f of the optical system of the conical light source is determined according to the required irradiation area A, the beam diameter d, the shooting distance L, and the relationship between the equivalent focal length of the concave mirror and the diffusion angle as follows:

[0016]

[0017] Preferably, the cross-frame CCD camera is provided with a lens, and a filter is provided on the lens.

[0018] Preferably, the resolution of the cross-frame CCD camera is greater than 2048 pixels×2048 pixels, the grayscale level is at least 12 bits, and the minimum cross-frame interval can be adjusted to less than 1 μs.

[0019] Preferably, when using a 532nm laser light source and a PSP coating of a PtFPP probe molecule, a 645nm±20nm filter is selected;

[0020] When the light intensity is insufficient, the filter bandwidth can be widened as needed, but the minimum passing wavelength shall not be less than 565nm.

[0021] Preferably, the synchronization control module mainly includes an infrared photoelectric switch and a high-precision synchronizer; the infrared photoelectric switch will detect the motion phase of the rotating part by emitting and receiving the reflected light of the rotating part, and provide a high-level pulse signal to the high-precision synchronizer. The high-precision synchronizer provides a laser light source trigger signal and a cross-frame camera acquisition signal by detecting the rising edge of the high-level pulse signal.

[0022] Preferably, when the cooperative repetitive working frequency fc of the laser light source and the cross-frame CCD camera is low, the output signal of the high-precision synchronizer is subjected to frequency division processing, and the frequency division coefficient αf≥fx / fc.

[0023] Preferably, the speckle equivalent diameter ds and the duty cycle γ are determined by the calculable performance of the PSP and the area Ad of the rotating component to be measured. Under the condition of Ad≤0.144m2, ds≤1mm and γ≤0.05 are adopted.

[0024] Beneficial effects:

[0025] The cross-frame CCD camera can quickly capture two images within a very short time interval. The laser light source can output a laser light source with a pulse width of 10ns. The fluorescence lifetime of the PSP photosensitive molecules is 10 to 50 microseconds. By controlling the cross-frame time of the cross-frame CCD camera, two frames of PSP fluorescence images can be quickly captured after laser pulse irradiation, and the surface pressure distribution can be obtained using the fluorescence lifetime method. Since both exposures are in microseconds, the motion blur of the rotating parts can be effectively controlled to make the image clearly visible.

[0026] Since the cross-frame CCD camera and laser light source need to run strictly synchronously, and their repetition frequency is low, much lower than the rotation frequency of the rotating parts, it is necessary to introduce a synchronization control module to shoot after the rotating parts reach a specific phase, so as to achieve phase locking of high-speed rotating parts.

[0027] A PSP coating with marked speckles is sprayed on the rotating surface to be measured. Both cross-frame CCD cameras can obtain PSP images with speckles. The speckle position information will be used for 3D-DSCM surface deformation calculation, and the PSP image will be used for surface pressure calculation. However, the PSP image will use the erosion and expansion method to bridge the speckle area to make the pressure distribution continuous and complete. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A schematic diagram of a synchronous measurement system for surface deformation and pressure distribution of a rotating component provided in a specific embodiment of the present invention;

[0030] Figure 2 A timing diagram of a synchronous measurement system for surface deformation and pressure distribution of a rotating component provided in a specific embodiment of the present invention.

[0031] Description of reference numerals:

[0032] Among them, 1 is a Nd:YAG laser light source, 2 is a laser beam, 3 is a cone light source, 4 is a cone beam, 5-1 is a left-side cross-frame CCD camera, 5-2 is a right-side cross-frame CCD camera, 6-1 is a left-side lens, 6-2 is a right-side lens, 7-1 is a left-side filter, 7-2 is a right-side filter, 8 is a rotating part to be measured, 9 is a rotating shaft of the rotating part, 10 is an infrared photoelectric switch, and 11 is a high-precision synchronizer;

[0033] T1 is the trigger signal of the infrared photoelectric switch, T2 is the laser light source pulse signal, Δt1 is the system delay from the trigger signal of the infrared photoelectric switch to the pulse of the laser light source, Image1 is the exposure interval of the first frame image captured by the cross-frame CCD camera, Image2 is the exposure interval of the second frame image captured by the cross-frame CCD camera, Δt2 is the time interval between the two exposure frames of the cross-frame CCD camera, and the shaded area and curve are the curves of the fluorescence intensity of the PSP stimulated radiation changing with time. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0036] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] like Figure 1 As shown, this embodiment provides a synchronous measurement system for the surface deformation and pressure distribution of a rotating component, which includes a laser light source module, an image acquisition module, a synchronous control module and a rotating component carrier.

[0038] The laser light source module is a laser light source capable of outputting a 10ns pulse width.

[0039] The image acquisition module includes two cross-frame CCD cameras, and the two cross-frame CCD cameras acquire two images within a set time interval.

[0040] The synchronization control module is used to provide a trigger signal for the laser light source module and a collection signal for the image collection module.

[0041] The rotating component carrier comprises a rotating component to be measured, and the surface of the rotating component to be measured is provided with PSP paint and is arranged with speckle marking points.

[0042] The cross-frame CCD camera can quickly capture two images within a very short time interval. The laser light source can output a laser light source with a pulse width of 10ns. The fluorescence lifetime of the PSP photosensitive molecules is 10 to 50 microseconds. By controlling the cross-frame time of the cross-frame CCD camera, two frames of PSP fluorescence images can be quickly captured after laser pulse irradiation, and the surface pressure distribution can be obtained using the fluorescence lifetime method. Since both exposures are in microseconds, the motion blur of the rotating parts can be effectively controlled to make the image clearly visible.

[0043] Since the cross-frame CCD camera and laser light source need to run strictly synchronously, and their repetition frequency is low, much lower than the rotation frequency of the rotating parts, it is necessary to introduce a synchronization control module to shoot after the rotating parts reach a specific phase, so as to achieve phase locking of high-speed rotating parts.

[0044] A PSP coating with marked speckles is sprayed on the rotating surface to be measured. Both cross-frame CCD cameras can obtain PSP images with speckles. The speckle position information will be used for 3D-DSCM surface deformation calculation, and the PSP image will be used for surface pressure calculation. However, the PSP image will use the erosion and expansion method to bridge the speckle area to make the pressure distribution continuous and complete.

[0045] In this embodiment, taking the FD-03 wind tunnel optical flow velocity measurement as an example, the synchronous measurement system of the surface deformation and pressure distribution of the rotating component is further described. The details are as follows:

[0046] Laser source module

[0047] The laser light source module is mainly composed of a Nd:YAG laser light source 1 and a cone light source 3. The laser beam 2 emitted by the Nd:YAG laser light source 1 is modulated into a cone light beam 4 through the cone light source 3. The Nd:YAG laser light source 1 is preferably a 532nm single-pulse Nd:YAG laser with a single-pulse pulse width of 10ns±2ns, and the required irradiation area A is greater than 0.25m 2 When the single pulse energy is required to be ≥500mJ; if a 532nm dual-cavity pulse Nd:YAG laser is used, it is not necessary to trigger the second cavity pulse; the equivalent focal length f of the optical system of the cone light source 3 is determined according to the required irradiation area A, beam diameter d, shooting distance L, and the relationship between the equivalent focal length of the concave mirror and the diffusion angle as follows:

[0048]

[0049] Image acquisition module

[0050] The image acquisition module is mainly composed of two sets of cross-frame CCD cameras 5-1, 5-2, lenses 6-1, 6-2, filters 7-1, 7-2. The cross-frame CCD camera is preferably a high-quality CCD camera with high resolution, high image grayscale and low cross-frame spacing. The resolution is recommended to be 2048 pixels × 2048 pixels or more, the grayscale is recommended to be 12 bits, and the minimum cross-frame spacing is recommended to be adjustable to less than 1μs. The lens is selected based on the shooting distance and shooting area, and the filter is selected based on the laser light source illumination wavelength and the PSP image radiation wavelength. In particular, a 532nm laser light source and a PSP coating of the PtFPP probe molecule are selected, and a 645nm±20nm filter is preferred. When the light intensity is insufficient, the filter bandwidth can be appropriately relaxed, but the minimum passing wavelength is not less than 565nm.

[0051] Synchronous control module

[0052] The synchronization control module is mainly composed of an infrared photoelectric switch 10 and a high-precision synchronizer 11, wherein the infrared photoelectric switch 10 detects the motion phase of the rotating part by emitting and receiving the reflected light of the rotating part, and provides a high-level pulse signal to the high-precision synchronizer 11. The high-precision synchronizer 11 provides a trigger signal of the Nd:YAG laser light source 1 and a cross-frame CCD camera 5-15-2 acquisition signal by detecting the rising edge of the high-level pulse signal.

[0053] In particular, when the cooperative repetitive working frequency fc of the Nd:YAG laser light source 1 and the two cross-frame CCD cameras 5-1 and 5-2 is low, it is impossible to completely match the rotation frequency fx of the tracking rotating component. At this time, the output signal of the high-precision synchronizer 11 is divided by software, and the division coefficient αf≥fx / fc, so that the Nd:YAG laser light source 1 and the two cross-frame CCD cameras 5-1 and 5-2 can capture effective image data.

[0054] Rotating parts carrier

[0055] The rotating component carrier is mainly composed of the rotating component to be measured 8 and the rotating shaft 9 of the rotating component. The surface of the rotating component to be measured 8 needs to be sprayed with high-sensitivity PSP coating first. After the coating is formed, speckle marking points are arranged on the surface. The speckle position information will be used for 3D-DSCM surface deformation calculation, and the PSP image will be used for surface pressure calculation. However, the PSP image will use the corrosion expansion method to bridge the speckle area to make the pressure distribution continuous and complete.

[0056] The speckle equivalent diameter ds and the duty cycle γ are determined by the calculable performance of the PSP and the area Ad of the rotating component 8 to be measured, which is generally Ad≤0.144m 2 Under the conditions, ds≤1mm and γ≤0.05 are preferred.

[0057] The working principle and timing of a supersonic flow field optical flow velocity measurement system involved in the present invention are as follows.

[0058] First, operate the rotating component 8 to be measured, make the Nd:YAG laser light source 1, the two cross-frame CCD cameras 5-1, 5-2, and the high-precision synchronizer 11 in working state, install the infrared photoelectric switch 10 and align it with the operating area of ​​the rotating component 8 to be measured, when the rotating component 8 to be measured runs to a specific phase, the infrared photoelectric switch 10 will output a high-level trigger signal T1, after a system delay Δt1, the high-precision synchronizer 11 outputs a signal T2 to trigger the Nd:YAG laser light source 1 and the two cross-frame CCD cameras 5-1, 5-2 to work, wherein the two cross-frame CCD cameras 5-1, 5-2 first capture the first frame image with an exposure interval of Image1, and then capture the second frame image with an exposure interval of Image2 after a time interval of Δt2.

[0059] In order to ensure the PSP image calculation effect based on the lifetime method, the grayscale ratio λI of the first frame image I1 and the second frame image I2 is ensured to satisfy the following relationship by controlling the time interval Δt2: λI=I1 / I2≈0.7.

[0060] In summary, the synchronous measurement system for surface deformation and pressure distribution of rotating parts provided in this embodiment can achieve the following objectives:

[0061] (1) Establishing 3D-DSCM binocular layout and PSP observation layout based on fluorescence lifetime method

[0062] Two cross-frame CCD cameras and Nd:YAG laser light sources were introduced to replace traditional cameras and continuous light sources, and a 3D-DSCM binocular layout and a PSP observation layout based on the fluorescence lifetime method were established. The cross-frame CCD camera can quickly collect two images in a very short time interval (as low as 200ns interval), and the Nd:YAG laser light source can output a laser light source with a pulse width of 10ns. The fluorescence lifetime of the PSP photosensitive molecule is 10 to 50 microseconds. By controlling the cross-frame time of the cross-frame CCD camera, two frames of PSP fluorescence images can be quickly captured after Nd:YAG laser pulse irradiation, and the surface pressure distribution can be obtained using the fluorescence lifetime method. Since both exposures are at the microsecond level, the motion blur of the rotating parts can be effectively controlled to make the image clear and visible.

[0063] (2) Achieve phase locking of high-speed rotating components

[0064] Since the cross-frame CCD camera and the Nd:YAG laser light source need to run strictly synchronously, and their repetition frequency is low, much lower than the rotation frequency of the rotating part, it is necessary to introduce high-precision synchronization equipment and photoelectric trigger switches to shoot after the rotating part reaches a specific phase. The present invention uses infrared sensing photoelectric switches and high-precision synchronization equipment to achieve phase locking of high-speed rotating parts.

[0065] (3) Synchronous acquisition of high signal-to-noise ratio surface deformation and surface pressure image information

[0066] A PSP coating with marked speckles is sprayed on the rotating surface to be measured, and a high-pass filter is installed in front of the lens to filter out the laser generated by the laser light source. Both cross-frame CCD cameras can obtain PSP images with speckles, of which the speckle position information will be used for 3D-DSCM surface deformation calculation, and the PSP image will be used for surface pressure calculation. However, the PSP image will use the erosion and expansion method to bridge the speckle area to make the pressure distribution continuous and complete.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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. A synchronous measurement system for surface deformation and pressure distribution of rotating parts, characterized in that: It includes a laser light source module, an image acquisition module, a synchronization control module and a rotating component carrier; The laser light source module is a laser light source capable of outputting a pulse width of 10ns; The image acquisition module includes two cross-frame CCD cameras, which acquire two images within a set time interval; The synchronization control module is used to provide a trigger signal for the laser light source module and a collection signal for the image collection module; The rotating component carrier comprises a rotating component to be measured, and the surface of the rotating component to be measured is provided with PSP coating and arranged with speckle marking points; The laser light source module comprises a laser light source and a cone light source, wherein the cone light source is arranged at the front end of the laser light source; The laser light source adopts a 532nm single pulse laser with a single pulse width of 10ns±2ns; When the irradiation area A is greater than 0.25m 2 When the single pulse energy is required to be ≥500mJ; If a 532nm dual-cavity pulse laser is used, it is not necessary to trigger the second cavity pulse; The synchronization control module mainly includes an infrared photoelectric switch and a high-precision synchronizer; the infrared photoelectric switch will detect the motion phase of the rotating part by emitting and receiving the reflected light of the rotating part, and provide a high-level pulse signal to the high-precision synchronizer at the same time. The high-precision synchronizer provides a laser light source trigger signal and a cross-frame camera acquisition signal by detecting the rising edge of the high-level pulse signal; When the cooperative repetitive working frequency fc of the laser light source and the cross-frame CCD camera is low, the output signal of the high-precision synchronizer is subjected to frequency division processing, and the frequency division coefficient αf ≥ fx / fc; The speckle equivalent diameter ds and duty cycle γ will be determined by the calculable performance of the PSP and the area Ad of the rotating component to be measured. Under the condition of Ad≤0.144m2, ds≤1mm and γ≤0.05 are used.

2. The synchronous measurement system for surface deformation and pressure distribution of rotating parts according to claim 1, characterized in that: The equivalent focal length f of the optical system of the conical light source is determined according to the required irradiation area A, the beam diameter d, the shooting distance L, and the relationship between the equivalent focal length of the concave mirror and the diffusion angle as follows: 。 3. The synchronous measurement system for surface deformation and pressure distribution of rotating parts according to claim 1, characterized in that: The cross-frame CCD camera is provided with a lens, and a filter is provided on the lens.

4. The synchronous measurement system for surface deformation and pressure distribution of rotating parts according to claim 3, characterized in that: The resolution of the cross-frame CCD camera is greater than 2048 pixels×2048 pixels, the grayscale level is at least 12 bits, and the minimum cross-frame interval can be adjusted to less than 1 μs.

5. The synchronous measurement system for surface deformation and pressure distribution of rotating parts according to claim 3, characterized in that: When using a 532nm laser light source and PSP coating with PtFPP probe molecules, a 645nm±20nm filter was selected; When the light intensity is insufficient, the filter bandwidth can be widened as needed, but the minimum passing wavelength shall not be less than 565nm.

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