Speed field and temperature field synchronous measurement method based on temperature-sensitive phosphorescent particles

Abstract

The invention provides a speed field and temperature field synchronous measurement method based on temperature-sensitive phosphorescent particles, and relates to the technical field of flow field observation.The method comprises the steps that the service life of the temperature-sensitive phosphorescent particles is measured, and a service life-temperature curve is obtained; obtaining a time sequence image of the temperature-sensitive phosphorescent particles; performing three-view separation processing on the time sequence image to obtain a processed image; performing three-dimensional reconstruction and trajectory fitting operation on the processed image to obtain a three-dimensional velocity field; acquiring a red total-resolution image of the temperature-sensitive phosphorescent particles irradiated by the light source; calculating the temperature-sensitive phosphorescent particle intensity of the red full-resolution image, and obtaining the self-luminous lifetime through the temperature-sensitive phosphorescent particle intensity; a three-dimensional temperature field is obtained through the service life-temperature curve and the self-luminous service life; and fusing the three-dimensional velocity field and the three-dimensional temperature field to obtain a three-dimensional velocity-temperature field. According to the method, the stability of reconstructing the three-dimensional velocity field and the precision of temperature measurement are improved through the three-color mask single-color camera and the service life method of the temperature-sensitive phosphorescent particles.

Description

Technical Field

[0001] The invention relates to the technical field of flow field observation, and in particular to a method for synchronously measuring velocity field and temperature field based on temperature-sensitive phosphorescent particles. Background Art

[0002] Flow field measurement technology has a wide range of applications in various fields. In the existing technology, particle image velocimetry (PIV) or particle tracking velocimetry (PTV) technology is often used to obtain fluid velocity information. Tunable semiconductor laser absorption spectroscopy (TDLAS) technology is usually used to measure the temperature field of a three-dimensional flow field.

[0003] However, the measurement of velocity field and temperature field is mostly carried out in steps, which cannot achieve the synchronous acquisition of velocity and temperature in the flow field, resulting in time or space errors in the measurement data, affecting the accuracy of the research. In addition, the existing synchronous measurement technology of velocity field and temperature field has the problem of too complex optical path system and too low spatial resolution and time resolution. Therefore, it is very necessary to design a synchronous measurement method of velocity field and temperature field based on temperature-sensitive phosphorescent particles. Summary of the invention

[0004] The purpose of the present invention is to provide a method for synchronously measuring velocity field and temperature field based on temperature-sensitive phosphorescent particles, so as to improve the stability of reconstructing three-dimensional velocity field and the accuracy of temperature measurement through a three-color mask single-color camera and a lifetime method of temperature-sensitive phosphorescent particles.

[0005] To achieve the above object, the present invention provides the following solutions: A method for synchronously measuring velocity field and temperature field based on temperature-sensitive phosphorescent particles comprises the following steps: The lifetime of the temperature-sensitive phosphorescent particles is measured to obtain a lifetime-temperature curve; Acquire a time-series image of the temperature-sensitive phosphorescent particles when they are illuminated by a light source; Perform three-view separation processing on the time series image to obtain a processed image; Perform three-dimensional reconstruction and trajectory fitting operations on the processed image to obtain a three-dimensional velocity field; Obtain a red full-resolution image of the temperature-sensitive phosphorescent particles after being illuminated by a light source; The intensity of the temperature-sensitive phosphorescent particles in the red full-resolution image is calculated through the three-dimensional velocity field to obtain the self-luminescence lifetime; The three-dimensional temperature field is obtained through the lifetime-temperature curve and the self-luminescence lifetime; The three-dimensional velocity field and the three-dimensional temperature field are fused to obtain the three-dimensional velocity-temperature field.

[0006] Optionally, the lifetime of the thermosensitive phosphorescent particles is measured to obtain a lifetime-temperature curve. The specific steps are: different phosphorescence decay constants of the thermosensitive phosphorescent particles at different temperatures are obtained according to the phosphorescence decay equation, and the lifetime-temperature curve is obtained by the change law of the phosphorescence decay constant with temperature.

[0007] Optionally, performing three-view separation processing on the time series images to obtain processed images includes: Perform perspective extraction operation on the time series image through the three colors of red, green and blue to obtain the original image; Perform an interpolation operation on the original image to obtain an interpolated image; A color crosstalk correction operation is performed on the interpolated image to obtain a processed image.

[0008] Optionally, performing three-view separation processing on the time series images to obtain processed images further includes: performing a volume calibration operation on the interpolated images to obtain a conversion relationship between two-dimensional image coordinates and three-dimensional world coordinates; the expression of the conversion relationship is: ;in, x j and y j Respectively represent the horizontal and vertical coordinates in the image coordinate system, X j , Y j and Z j are all three-dimensional coordinates in the world coordinate system. a 11 , a 12 ,..., a 34 are the coefficients of the matrix.

[0009] Optionally, three-dimensional reconstruction and trajectory fitting operations are performed on the processed image to obtain a three-dimensional velocity field, including: obtaining a three-dimensional particle distribution of a first portion of the processed image by triangulation; Performing a particle position prediction operation on the second part of the processed image by using three-dimensional particle distribution and Wiener filtering to obtain a prediction result; Perform jitter adjustment on the prediction results to obtain particle trajectories; The three-dimensional velocity field is obtained through the three-dimensional distribution of particle trajectories.

[0010] Optionally, the prediction result is jitter-adjusted to obtain a particle trajectory, including: Performing coordinate movement operation on the three-dimensional world coordinates of the prediction result to obtain a movement result; The residual-displacement relationship curve is obtained by the residual of the projected image of the moving result and the processed image; The particle position prediction operation is performed again on the prediction result through the residual-displacement relationship curve to obtain the particle trajectory.

[0011] Optionally, calculating the intensity of the temperature-sensitive phosphorescent particles of the red full-resolution image, and obtaining the self-luminescence lifetime through the intensity of the temperature-sensitive phosphorescent particles, comprises: The red particle distribution is obtained by performing two-dimensional particle tracking on the red full-resolution image through the three-dimensional velocity field; The spontaneous luminescence lifetime was calculated using the red particle distribution and phosphorescence decay equation.

[0012] The present invention discloses the following technical effects: a method for synchronously measuring a velocity field and a temperature field based on thermosensitive phosphorescent particles provided by the present invention comprises: measuring the lifetime of the thermosensitive phosphorescent particles to obtain a lifetime-temperature curve; obtaining a time series image when the thermosensitive phosphorescent particles are irradiated by a light source; performing three-view separation processing on the time series image to obtain a processed image; performing three-dimensional reconstruction and trajectory fitting operations on the processed image to obtain a three-dimensional velocity field; obtaining a red full-resolution image after the thermosensitive phosphorescent particles are irradiated by the light source; calculating the intensity of the thermosensitive phosphorescent particles in the red full-resolution image through the three-dimensional velocity field to obtain the self-luminescence lifetime; obtaining a three-dimensional temperature field through the lifetime-temperature curve and the self-luminescence lifetime; and fusing the three-dimensional velocity field and the three-dimensional temperature field to obtain a three-dimensional velocity-temperature field. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0014] Figure 1 It is a flow chart of the method for synchronously measuring velocity field and temperature field of the present invention; Figure 2 is a life-temperature curve diagram of the present invention; Figure 3 It is a three-view separation flow chart of the present invention; Figure 4 It is a schematic diagram of the three-dimensional velocity-temperature field of the present invention. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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.

[0016] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] like Figure 1 As shown, the embodiment of the present invention provides a method for synchronously measuring velocity field and temperature field based on temperature-sensitive phosphorescent particles, comprising the following steps: Step 100: measuring the lifetime of the temperature-sensitive phosphorescent particles to obtain a lifetime-temperature curve; Specifically, first heat the thermostat to the lowest preset temperature, use a 385nm ultraviolet LED light source to excite the temperature-sensitive phosphorescent particles, turn off the ultraviolet light, and immediately use a camera to take multiple consecutive photos of the temperature-sensitive phosphorescent particles, record the particle imaging intensity at different times, and then calculate the phosphorescence decay constant at that temperature using the phosphorescence decay equation. Then increase the temperature of the thermostat to other different preset temperatures, use the same method to obtain the phosphorescence decay constants corresponding to different temperatures, and obtain the life-temperature curve based on the change of the phosphorescence decay constant with temperature. The life-temperature curve is shown in the figure below. Figure 2 shown.

[0018] It should be noted that the phosphorescence decay constant calculation is performed multiple times at each temperature, and the average value of the phosphorescence decay constants obtained multiple times is taken as the final phosphorescence decay constant at that temperature. 4+ The particle size is D50 = 6.5 ± 1.5 μm, and the particle concentration is 2.87*10 5 Pieces / ml.

[0019] Step 200: Acquire a time-series image of the temperature-sensitive phosphorescent particles when they are illuminated by a light source; Specifically, a high-energy white LED lamp or a halogen lamp light source is used to irradiate the temperature-sensitive phosphorescent particles, and a three-color mask color time-series image of the particles is acquired through a three-color mask single color camera.

[0020] Step 300: Perform three-view separation processing on the time-series image to obtain a processed image; the specific steps are as follows: Figure 3 As shown, including: Step 301: extracting original images of three different viewing angles of the time series image through three color channels: red, green and blue; Step 302: performing an interpolation operation on the original image by using a method such as dual three-color interpolation, bilinear interpolation, pattern recognition interpolation, or deep learning interpolation to eliminate holes in the original image caused by a mosaic effect, thereby obtaining an interpolated image; Step 303: Obtain a single-aperture interpolation image by blocking two apertures of the three-color mask single-color camera, and perform a color crosstalk correction operation on the interpolation image using the color crosstalk correction coefficient of the single-aperture interpolation image to remove ghost pixels, thereby obtaining a processed image.

[0021] Specifically, performing three-view separation processing on the time series image to obtain a processed image, and further comprising: performing a volume calibration operation on the interpolated image to obtain a conversion relationship between two-dimensional image coordinates and three-dimensional world coordinates; Specifically, this embodiment performs volume calibration operation through a plane calibration plate. The two-dimensional position information of the plane calibration plate is known. By moving the calibration plate up and down in the depth direction, the two-dimensional position information at different depths of field is obtained, and the three-dimensional position of the calibration plate is determined according to all the known two-dimensional position information and the position in the depth direction. The expression of the conversion relationship between the two-dimensional image coordinates and the three-dimensional world coordinates is: ; in, x j and y j Respectively represent the horizontal and vertical coordinates in the image coordinate system, X j , Y j and Z j are all three-dimensional coordinates in the world coordinate system. a 11 , a 12 ,..., a 34 These are the coefficients that constitute the matrix. These coefficients are determined through the calibration process. They contain the internal parameters of the camera (such as focal length, principal point coordinates) and external parameters (such as the position and attitude of the camera).

[0022] Step 400: performing three-dimensional reconstruction and trajectory fitting operations on the processed image to obtain a three-dimensional velocity field; Specifically, first, the 2D particle pixel coordinates in the first four frames of processed images are identified, and the 3D particle distribution is calculated by triangulation. Then, the 2D projections of the known particles in the 3D particle distribution are removed from the first four frames of processed images, and the 3D particle distribution of the removed images is re-obtained. The above iterative process is repeated until the 3D positions of all particles are obtained.

[0023] Then, based on the three-dimensional particle distribution, the particle positions of subsequent frames except the first four frames in the processed image are predicted by Wiener filtering, the predicted results are compared with the real positions obtained by the camera, and the particle trajectories are obtained by jitter adjustment.

[0024] Finally, the three-dimensional velocity field is obtained through the three-dimensional distribution of particle trajectories.

[0025] More specifically, the specific steps of jitter adjustment are: perform a ±1 movement operation on the three-dimensional world coordinates (x, y, z) of the prediction result. The residual-displacement relationship curve is fitted by the residual between the projected image and the processed image after the coordinate movement. The coordinate with the smallest residual in the residual-displacement relationship curve is determined as the correct three-dimensional world coordinate, and the particle position is re-predicted for the prediction result according to the correct three-dimensional world coordinate to obtain the particle trajectory.

[0026] Step 500: Acquire a red full-resolution image of the temperature-sensitive phosphorescent particles after being irradiated by a light source; Specifically, turn off the high-energy white LED light or halogen light source, and immediately use 385nm pulse light to illuminate the temperature-sensitive phosphorescent particles. After the illumination is completed, a three-color mask image of the initial phosphorescence intensity of the particles after stimulation from strong to weak is obtained through a three-color mask single-color camera. A red full-resolution image of the red channel is extracted from the three-color mask image. The red full-resolution image contains the phosphorescence intensity information of the temperature-sensitive phosphorescent particles.

[0027] Step 600: Calculate the intensity of the temperature-sensitive phosphorescent particles in the red full-resolution image, and obtain the self-luminescence lifetime through the intensity of the temperature-sensitive phosphorescent particles; Specifically, the position of the two-dimensional particles in the red full-resolution image is tracked in the three-dimensional velocity field to obtain the particle distribution of the two-dimensional particles in the three-dimensional velocity field. Based on the phosphorescence decay equation, the decay constant is calculated by the particle distribution and the different particle intensities at different times in the three-color mask image, and the decay constant is used as the self-luminescence lifetime.

[0028] Step 700: Obtain a three-dimensional temperature field through the lifetime-temperature curve and the self-luminous lifetime; The different temperature distributions corresponding to different self-luminous lifetimes are queried through the lifetime-temperature curve, thereby constructing a three-dimensional temperature field.

[0029] Step 800: Fusing the three-dimensional velocity field and the three-dimensional temperature field to obtain a three-dimensional velocity-temperature field. Figure 4 shown.

[0030] The beneficial effects of the present invention are as follows: 1) The resolution of the acquired image is improved by using the three-view separation technology of the three-color mask single color camera; 2) The 3D velocity field was constructed through 3D reconstruction and jitter adjustment, which improved the accuracy of the construction process; 3) The three-dimensional temperature field is obtained using the lifetime-temperature curve of the thermosensitive phosphorescent particles, which improves the stability of the acquisition process and the accuracy of temperature measurement.

[0031] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0032] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for synchronously measuring velocity field and temperature field based on temperature-sensitive phosphorescent particles, characterized in that: The steps include: Measuring the lifetime of the temperature-sensitive phosphorescent particles to obtain a lifetime-temperature curve; Acquiring a time-series image of the temperature-sensitive phosphorescent particle when it is irradiated by a light source; Performing three-view separation processing on the time-series image to obtain a processed image; Performing three-dimensional reconstruction and trajectory fitting operations on the processed image to obtain a three-dimensional velocity field; Acquire a red full-resolution image of the temperature-sensitive phosphorescent particles after being irradiated by the light source; Calculating the intensity of the temperature-sensitive phosphorescent particles of the red full-resolution image, and obtaining the self-luminescence lifetime through the intensity of the temperature-sensitive phosphorescent particles; Obtaining a three-dimensional temperature field through the lifetime-temperature curve and the spontaneous luminescence lifetime; The three-dimensional velocity field and the three-dimensional temperature field are fused to obtain a three-dimensional velocity-temperature field.

2. The method for synchronously measuring velocity field and temperature field based on temperature-sensitive phosphorescent particles according to claim 1, characterized in that: The lifetime of the thermosensitive phosphorescent particles is measured to obtain a lifetime-temperature curve. The specific steps are: different phosphorescence decay constants of the thermosensitive phosphorescent particles at different temperatures are obtained according to the phosphorescence decay equation, and the lifetime-temperature curve is obtained according to the change law of the phosphorescence decay constant with temperature.

3. The method for synchronously measuring velocity field and temperature field based on temperature-sensitive phosphorescent particles according to claim 1, characterized in that: The time-series images are subjected to three-view separation processing to obtain processed images, including: Performing a perspective extraction operation on the time-series image using red, green and blue colors to obtain an original image; Performing an interpolation operation on the original image to obtain an interpolated image; A color crosstalk correction operation is performed on the interpolated image to obtain the processed image.

4. The method for synchronously measuring velocity field and temperature field based on temperature-sensitive phosphorescent particles according to claim 3, characterized in that: The three-view separation process is performed on the time series image to obtain a processed image, and the process further includes: performing a volume calibration operation on the interpolated image to obtain a conversion relationship between a two-dimensional image coordinate and a three-dimensional world coordinate; the expression of the conversion relationship is: ;in, x j and y j Respectively represent the horizontal and vertical coordinates in the image coordinate system, X j , Y j and Z j are all three-dimensional coordinates in the world coordinate system. a 11 , a 12 ,..., a 34 are the coefficients of the matrix.

5. The method for synchronously measuring velocity field and temperature field based on temperature-sensitive phosphorescent particles according to claim 1, characterized in that: Performing three-dimensional reconstruction and trajectory fitting operations on the processed image to obtain a three-dimensional velocity field includes: obtaining a three-dimensional particle distribution of a first portion of the processed image by triangulation; Performing a particle position prediction operation on the second part of the processed image by using the three-dimensional particle distribution and Wiener filtering to obtain a prediction result; Performing jitter adjustment on the prediction result to obtain a particle trajectory; The three-dimensional velocity field is obtained through the three-dimensional distribution of the particle trajectories.

6. The method for synchronously measuring velocity field and temperature field based on temperature-sensitive phosphorescent particles according to claim 5, characterized in that: The prediction result is subjected to dithering adjustment to obtain a particle trajectory, including: Performing a coordinate movement operation on the three-dimensional world coordinates of the prediction result to obtain a movement result; Obtaining a residual-displacement relationship curve through the residual of the projection image of the movement result and the processed image; The particle position prediction operation is re-performed on the prediction result through the residual-displacement relationship curve to obtain the particle trajectory.

7. The method for synchronously measuring velocity field and temperature field based on temperature-sensitive phosphorescent particles according to claim 1, characterized in that: Calculating the intensity of the temperature-sensitive phosphorescent particles of the red full-resolution image, and obtaining the self-luminescence lifetime through the intensity of the temperature-sensitive phosphorescent particles, including: Performing two-dimensional particle tracking on the red full-resolution image through the three-dimensional velocity field to obtain red particle distribution; The self-luminescence lifetime is calculated by the red particle distribution and the phosphorescence decay equation.

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