A method for simultaneously measuring a velocity field and a temperature field based on temperature-sensitive phosphor particles

Abstract

The application provides a speed field and temperature field synchronous measurement method based on temperature-sensitive phosphor particles, and relates to the technical field of flow field observation. The method comprises the following steps: performing lifetime measurement on the temperature-sensitive phosphor particles to obtain a lifetime-temperature curve; acquiring a time sequence image of the temperature-sensitive phosphor 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 speed field; acquiring a red full-resolution image of the temperature-sensitive phosphor particles after being irradiated by a light source; calculating the temperature-sensitive phosphor particle intensity of the red full-resolution image, and obtaining spontaneous light lifetime through the temperature-sensitive phosphor particle intensity; obtaining a three-dimensional temperature field through the lifetime-temperature curve and the spontaneous light lifetime; and fusing the three-dimensional speed field and the three-dimensional temperature field to obtain a three-dimensional speed-temperature field. The method improves the stability of the reconstructed three-dimensional speed field and the accuracy of the temperature measurement through a three-color mask single-color camera and the lifetime method of the temperature-sensitive phosphor particles.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flow field observation, in particular to a velocity field and temperature field synchronous measurement method based on temperature-sensitive phosphor particles. BACKGROUND

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

[0003] However, the measurement of the velocity field and the temperature field is mostly carried out in steps, and the velocity and the temperature in the flow field cannot be obtained synchronously, resulting in time or space errors in the measurement data and affecting the accuracy of the research. Moreover, the existing velocity field and temperature field synchronous measurement technology has the problems of overly complex optical system, low spatial resolution and low time resolution. Therefore, it is necessary to design a velocity field and temperature field synchronous measurement method based on temperature-sensitive phosphor particles. SUMMARY

[0004] The purpose of the present application is to provide a velocity field and temperature field synchronous measurement method based on temperature-sensitive phosphor particles, so as to improve the stability of the reconstructed three-dimensional velocity field and the accuracy of the temperature measurement by using a three-color mask single-color camera and the lifetime method of temperature-sensitive phosphor particles.

[0005] To achieve the above-mentioned purpose, the present application provides the following solutions:

[0006] A velocity field and temperature field synchronous measurement method based on temperature-sensitive phosphor particles comprises the following steps:

[0007] Lifetime measurement is performed on the temperature-sensitive phosphor particles to obtain a lifetime-temperature curve;

[0008] A time sequence image of the temperature-sensitive phosphor particles irradiated by a light source is obtained;

[0009] The time sequence image is subjected to three-view separation processing to obtain a processed image;

[0010] The processed image is subjected to three-dimensional reconstruction and trajectory fitting operations to obtain a three-dimensional velocity field;

[0011] A red full-resolution image of the temperature-sensitive phosphor particles irradiated by the light source is obtained;

[0012] The intensity of the temperature-sensitive phosphor particles in the red full-resolution image is calculated by using the three-dimensional velocity field to obtain the spontaneous light lifetime;

[0013] a three-dimensional temperature field is obtained through the lifetime-temperature curve and the spontaneous light lifetime;

[0014] a three-dimensional velocity-temperature field is obtained by fusing the three-dimensional velocity field and the three-dimensional temperature field.

[0015] Optionally, the lifetime of the temperature-sensitive phosphor particles is measured to obtain a lifetime-temperature curve, and the specific steps are as follows: different phosphor decay constants of the temperature-sensitive phosphor particles at different temperatures are obtained according to a phosphor decay equation, and the lifetime-temperature curve is obtained through the change rule of the phosphor decay constant with temperature.

[0016] Optionally, the time-series image is subjected to three-view separation processing to obtain a processed image, including:

[0017] The time-series image is subjected to view extraction operation through red, green and blue three colors to obtain an original image;

[0018] The original image is subjected to interpolation operation to obtain an interpolated image;

[0019] The interpolated image is subjected to color crosstalk correction operation to obtain the processed image.

[0020] Optionally, the time-series image is subjected to three-view separation processing to obtain a processed image, and further including: the interpolated image is subjected to body calibration operation to obtain a conversion relationship between two-dimensional image coordinates and three-dimensional world coordinates; the expression of the conversion relationship is: ; wherein, x j and y j x and y respectively represent horizontal and vertical coordinates in an image coordinate system, X j , Y j and Z j are all three-dimensional coordinates in a world coordinate system, a 11 , a 12 , a 34 are all coefficients of a matrix.

[0021] Optionally, the processed image is subjected to three-dimensional reconstruction and trajectory fitting operation to obtain a three-dimensional velocity field, including:

[0022] The three-dimensional particle distribution of a first part of the processed image is obtained through triangulation method;

[0023] The particle position of a second part of the processed image is predicted through three-dimensional particle distribution and Wiener filtering to obtain a prediction result;

[0024] The prediction result is dithered to obtain a particle trajectory.

[0025] A three-dimensional velocity field is obtained through the three-dimensional distribution of the particle trajectory.

[0026] Optionally, the prediction result is dithered to obtain a particle trajectory, including:

[0027] A three-dimensional world coordinate of the prediction result is subjected to a coordinate moving operation to obtain a moving result.

[0028] A residual-displacement relationship curve is obtained through a residual of a projection image of the moving result and a processing image.

[0029] The prediction result is subjected to a particle position prediction operation again through the residual-displacement relationship curve to obtain a particle trajectory.

[0030] Optionally, the temperature-sensitive phosphor particle intensity of the red full-resolution image is calculated, and the self-luminous lifetime is obtained through the temperature-sensitive phosphor particle intensity, including:

[0031] A red particle distribution is obtained through two-dimensional particle tracking of the red full-resolution image through the three-dimensional velocity field.

[0032] The self-luminous lifetime is calculated through the red particle distribution and a phosphor decay equation.

[0033] The present application discloses the following technical effects: the method for synchronously measuring a velocity field and a temperature field based on temperature-sensitive phosphor particles provided by the present application, which comprises: performing lifetime measurement on temperature-sensitive phosphor particles to obtain a lifetime-temperature curve; acquiring a time sequence image of the temperature-sensitive phosphor particles when they are irradiated by a light source; performing three-view angle separation processing on the time sequence image to obtain a processing image; performing three-dimensional reconstruction and trajectory fitting operations on the processing image to obtain a three-dimensional velocity field; acquiring a red full-resolution image of the temperature-sensitive phosphor particles after they are irradiated by the light source; calculating the temperature-sensitive phosphor particle intensity of the red full-resolution image through the three-dimensional velocity field to obtain a self-luminous lifetime; obtaining a three-dimensional temperature field through the lifetime-temperature curve and the self-luminous 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 DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0035] Figure 1 The flow chart of the method for synchronously measuring a velocity field and a temperature field of the present application;

[0036] Figure 2 Lifetime-temperature curve of the present application;

[0037] Figure 3 Three-view separation flowchart of the present application;

[0038] Figure 4 Three-dimensional velocity-temperature field schematic diagram of the present application. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0040] The above purposes, features and advantages of the present application can be more obvious and easy to understand. The present application will be further described in detail below with reference to the drawings and specific embodiments.

[0041] As Figure 1 shown, the embodiment of the present application provides a velocity field and temperature field synchronous measurement method based on temperature-sensitive phosphor particles, which comprises the following steps:

[0042] Step 100: Lifetime measurement is performed on the temperature-sensitive phosphor particles to obtain a lifetime-temperature curve;

[0043] Specifically, first, the thermostat is heated to the lowest preset temperature. After the temperature-sensitive phosphor particles are excited by using a 385nm ultraviolet LED light source, the ultraviolet light is turned off, and the camera is used to take continuous multiple photographs of the temperature-sensitive phosphor particles immediately, the imaging intensity of the particles at different times is recorded, and then the phosphor decay constant at this temperature is calculated through the phosphor decay equation. Then the temperature of the thermostat is increased to other different preset temperatures, and the same method is used to obtain the phosphor decay constants corresponding to different temperatures, and the lifetime-temperature curve is obtained according to the variation law of the phosphor decay constant with temperature. The lifetime-temperature curve is shown in Figure 2 .

[0044] It should be noted that the phosphor decay constant is calculated multiple times at each temperature, and the average value of the multiple obtained phosphor decay constants is taken as the final phosphor decay constant at this temperature. The temperature-sensitive phosphor particles used in this embodiment are Mg4FGeO6:Mn 4+ . The particle size of the particles is D50=6.5±1.5μm, and the particle concentration is 2.87*10 5 per ml.

[0045] Step 200: Obtain the time sequence image of the temperature-sensitive phosphor particles when irradiated by the light source;

[0046] Specifically, the temperature-sensitive phosphor particles are irradiated using a high-energy white LED light or a halogen light source, and a three-color mask color time sequence image of the particles is acquired by a three-color mask single-color camera.

[0047] Step 300: performing three-view separation processing on the time sequence image to obtain a processed image; the specific steps are as shown in the following Figure 3

[0048] Step 301: extracting original images of three different views of the time sequence image through red, green and blue three color channels;

[0049] Step 302: performing interpolation operation on the original images by a double three-color interpolation, a bilinear interpolation, a pattern recognition interpolation or a deep learning interpolation, so as to eliminate the holes in the original images caused by the mosaic effect, thereby obtaining interpolated images;

[0050] Step 303: obtaining a single-aperture interpolated image through two light apertures of the occlusion three-color mask single-color camera, and performing color crosstalk correction operation on the interpolated image through a color crosstalk correction coefficient of the single-aperture interpolated image, so as to remove ghost pixels, thereby obtaining a processed image.

[0051] Specifically, the three-view separation processing on the time sequence image to obtain the processed image further includes: performing volume calibration operation on the interpolated images to obtain a conversion relationship between two-dimensional image coordinates and three-dimensional world coordinates.

[0052] Specifically, the embodiment performs volume calibration operation through a plane calibration board. The two-dimensional position information of the plane calibration board is known, the two-dimensional position information at different depth positions is acquired by moving the calibration board up and down in the depth direction, and the three-dimensional position of the calibration board is determined according to all 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:

[0053] ;

[0054] wherein, x j and y j are the horizontal and vertical coordinates in the image coordinate system, X j , Y j and Z j are three-dimensional coordinates in the world coordinate system, a 11 , a 12 , a 34 ​are the coefficients of the matrix, which are determined by a calibration process and contain the intrinsic parameters of the camera (such as focal length, principal point coordinates) and extrinsic parameters (such as the position and pose of the camera).

[0055] Step 400: performing three-dimensional reconstruction and trajectory fitting operations on the processing images to obtain a three-dimensional velocity field;

[0056] Specifically, first, the two-dimensional particle pixel coordinates in the first four frames of processing images are identified, and the three-dimensional particle distribution is calculated by triangulation. Then, the two-dimensional projection of the known particles in the three-dimensional particle distribution is removed from the first four frames of processing images, and the three-dimensional particle distribution of the removed images is reacquired. The above iteration process is repeated until the three-dimensional positions of all particles are obtained.

[0057] Then, based on the three-dimensional particle distribution, the particle positions of the subsequent frames after the first four frames in the processing images are predicted by Wiener filtering, the prediction results are compared with the real positions obtained by the camera, and the particle trajectories are obtained by jitter adjustment.

[0058] Finally, the three-dimensional velocity field is obtained by the three-dimensional distribution of the particle trajectories.

[0059] More specifically, the specific steps of jitter adjustment are: moving the three-dimensional world coordinates (x, y, z) of the prediction results by ±1 respectively. The residual error between the projection image after coordinate movement and the processing image is fitted to obtain a residual error-displacement relationship curve. The coordinates with the minimum residual error in the residual error-displacement relationship curve are determined as the correct three-dimensional world coordinates, and the prediction of particle positions is re-performed according to the correct three-dimensional world coordinates to obtain the particle trajectories.

[0060] Step 500: obtaining a red full-resolution image of the temperature-sensitive phosphor particles after being irradiated by a light source;

[0061] Specifically, the high-energy white LED light source or halogen light source is turned off, and the temperature-sensitive phosphor particles are immediately illuminated by a 385nm pulsed light. After the illumination is completed, the initial phosphor intensity of the particles after excitation is obtained by a three-color mask single-color camera to obtain a three-color mask image from strong to weak. The red full-resolution image of the red channel is extracted from the three-color mask image. The red full-resolution image contains the phosphor intensity information of the temperature-sensitive phosphor particles.

[0062] Step 600: calculating the temperature-sensitive phosphor particle intensity of the red full-resolution image, and obtaining the self-luminous lifetime by the temperature-sensitive phosphor particle intensity;

[0063] Specifically, the two-dimensional particle position in the red full resolution image is tracked in the three-dimensional velocity field to obtain the particle distribution of the two-dimensional particle in the three-dimensional velocity field. Based on the phosphor decay equation, the decay constant is calculated by the particle distribution and different particle intensities at different times in the three-color mask image, and the decay constant is taken as the spontaneous light lifetime.

[0064] Step 700: obtaining a three-dimensional temperature field through the lifetime-temperature curve and the spontaneous light lifetime;

[0065] The three-dimensional temperature field is constructed by querying different temperature distributions corresponding to different spontaneous light lifetimes through the lifetime-temperature curve.

[0066] Step 800: fusing the three-dimensional velocity field and the three-dimensional temperature field to obtain a three-dimensional velocity-temperature field. The three-dimensional velocity-temperature field of the embodiment is shown in FIG. 8. Figure 4

[0067] The beneficial effects of the present application are as follows:

[0068] 1) The resolution of the obtained image is improved through the three-view separation technology of the three-color mask single-color camera;

[0069] 2) The three-dimensional velocity field is constructed through three-dimensional reconstruction and jitter adjustment, and the accuracy of the construction process is improved;

[0070] 3) The three-dimensional temperature field is obtained using the lifetime-temperature curve of the temperature-sensitive phosphor particles, the stability of the acquisition process is improved, and the accuracy of the temperature measurement is improved.

[0071] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0072] The principle and implementation manner of the present application are described by applying specific examples in the present application. The above embodiment description is only used to help understand the method of the present application and its core idea; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation manner and application range will be changed. In conclusion, the content of the specification should not be understood as a limitation of the present application.​

Claims

1. A method for simultaneous measurement of velocity field and temperature field based on temperature-sensitive phosphor particles, characterized in that, The method comprises the following steps: Performing lifetime measurement on the temperature-sensitive phosphor particles to obtain a lifetime-temperature curve; Obtaining a time sequence image of the temperature-sensitive phosphor particles irradiated by a light source; Performing three-view separation processing on the time sequence 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 of the temperature-sensitive phosphor particles after being irradiated by the light source; Calculating the temperature-sensitive phosphor particle intensity of the red full-resolution image, and obtaining a spontaneous light lifetime through the temperature-sensitive phosphor particle intensity; Obtaining a three-dimensional temperature field through the lifetime-temperature curve and the spontaneous light lifetime; Fusing the three-dimensional velocity field and the three-dimensional temperature field to obtain a three-dimensional velocity-temperature field; The specific steps of performing three-dimensional reconstruction and trajectory fitting operations on the processed image to obtain a three-dimensional velocity field comprise: Obtaining a three-dimensional particle distribution of a first part of the processed image through triangulation; Performing a particle position prediction operation on a second part of the processed image through the three-dimensional particle distribution and Wiener filtering to obtain a prediction result; 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; Re-performing the particle position prediction operation on the prediction result through the residual-displacement relationship curve to obtain a particle trajectory; Obtaining the three-dimensional velocity field through the three-dimensional distribution of the particle trajectory; The specific steps of calculating the temperature-sensitive phosphor particle intensity of the red full-resolution image, and obtaining a spontaneous light lifetime through the temperature-sensitive phosphor particle intensity comprise: Performing two-dimensional particle tracking on the red full-resolution image through the three-dimensional velocity field to obtain a red particle distribution; Calculating the spontaneous light lifetime through the red particle distribution and a phosphor decay equation.

2. The method according to claim 1, wherein The specific steps of performing lifetime measurement on the temperature-sensitive phosphor particles to obtain a lifetime-temperature curve comprise: obtaining different phosphor decay constants of the temperature-sensitive phosphor particles at different temperatures according to a phosphor decay equation, and obtaining the lifetime-temperature curve through the variation law of the phosphor decay constants with temperature. 3.The method according to claim 1, wherein, The three-view separation processing on the time sequence image to obtain a processed image comprises: Performing view extraction operations on the time sequence image through red, green and blue three colors to obtain an original image; Performing interpolation operations on the original image to obtain an interpolated image; Performing color crosstalk correction operations on the interpolated image to obtain the processed image.

4. The method according to claim 3, wherein The time sequence image is subjected to three-view separation processing to obtain a processed image, and the method further comprises: performing a body calibration operation on the interpolation image to obtain a conversion relationship between two-dimensional image coordinates and three-dimensional world coordinates; an expression of the conversion relationship is: ; wherein, x j and y j represent a horizontal coordinate and a vertical coordinate in an image coordinate system respectively, X j , Y j and Z j are three-dimensional coordinates in a world coordinate system, a 11 , a 12 , a 34 are coefficients of a matrix.

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