A flow parameter measurement method and system based on digital light processing technology

Abstract

The present invention relates to a flow parameter measurement method and system based on digital light processing technology. The method comprises: sequentially emitting monochromatic light of three primary colors, each monochromatic light having the same duration; the monochromatic light is incident on a DMD chip and modulated by the DMD chip to generate a light sheet; the light sheet is irradiated onto a flow field measurement area and illuminates tracer particles; a color CCD camera, with its shooting direction perpendicular to the light sheet, is used for long-term exposure to obtain a color particle image containing the three primary colors; the color particle image is decoupled to obtain three monochromatic particle images; and the three-dimensional velocity field and three-dimensional acceleration field of the flow field measurement area are calculated based on the three monochromatic particle images. Compared with existing technologies, the present invention has the advantages of high detection efficiency, low cost, and high measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the field of fluid mechanics, and in particular to a flow parameter measurement method and system based on digital light processing technology. Background Art

[0002] Particle Image Velocimetry (PIV) technology is a non-contact, non-interference method for quantitatively measuring spatial flow fields. Traditional PIV technology disperses tiny tracer particles in a fluid, records the movement of the tracer particles with the fluid through continuous laser illumination and camera photography, and then calculates the particle motion information from the continuous images based on image processing algorithms to approximate the spatial velocity of the fluid. However, traditional PIV technology requires taking two images and can only obtain velocity information. Acceleration and pressure information are obtained by solving the fluid dynamics governing equations, the Navier-Stokes (NS) equations, which is inefficient. Moreover, the calculated acceleration is obtained by interpolating the two images, which has poor accuracy. Secondly, acceleration can also be calculated based on three consecutive images. However, due to the complex decoupling process between the three consecutive black and white images, the particle image obtained by shooting is often a single trajectory, making it difficult to extract particle information at each moment. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a flow parameter measurement method and system based on digital light processing technology, which has high detection efficiency, low cost and high measurement accuracy.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] A flow parameter measurement method based on digital light processing technology, comprising:

[0006] The three primary colors of monochromatic light are emitted successively, and the duration of each monochromatic light is the same;

[0007] The monochromatic light is incident on the DMD chip and is regulated by the DMD chip to generate a sheet light;

[0008] The light sheet is irradiated on the flow field measurement area and illuminates the tracer particles. A color CCD camera with a shooting direction perpendicular to the light sheet is used for long exposure to obtain a color particle image containing three primary colors.

[0009] Decouple the color particle image to obtain three monochrome particle images, and calculate the three-dimensional velocity field and three-dimensional acceleration field in the flow field measurement area based on the three monochrome particle images;

[0010] By periodically changing the color of monochromatic light and delaying exposure, a color particle image containing three primary colors is obtained. The color particle image contains flow field information at three different moments. At the same time, through the cross-correlation algorithm, the flow field information at three different moments can be obtained. Further calculations can obtain the three-dimensional velocity field and three-dimensional acceleration field, which can reduce the number of images captured by the camera and improve detection efficiency. At the same time, this method based on optical digital modulation reduces the number of optical components and control displacement devices used in particle image velocimetry technology, greatly reducing costs.

[0011] Digital modulation of light sheets based on the DMD chip can produce light sheets with stable light intensity, uniform distribution, and fixed thickness, with high measurement accuracy.

[0012] Furthermore, the monochromatic light emission process includes:

[0013] Irradiating a monochromatic light source onto a DLP color wheel and rotating the DLP color wheel at a constant speed simultaneously can obtain monochromatic light of three primary colors. This method can obtain monochromatic light of three primary colors stably and at high frequency, has a simple structure and is low in cost.

[0014] Furthermore, the DLP color wheel and the color CCD camera are controlled to run synchronously through a synchronous controller to ensure detection accuracy and achieve low difficulty.

[0015] Furthermore, the calculation process of the three-dimensional velocity field and the three-dimensional acceleration field of the flow field includes:

[0016] According to the first monochrome particle image and the second monochrome particle image, the first velocity vector V1=(u1, v1) of the flow field is obtained by image cross-correlation algorithm, where u1 and v1 are the first velocities of the flow field along the x-direction and the y-direction respectively;

[0017] According to the second and third monochrome particle images, the second velocity vector V2 = (u2, v2) of the flow field is obtained by image cross-correlation algorithm, where u2 and v2 are the second velocities of the flow field along the x and y directions, respectively.

[0018] According to the first velocity and the second velocity, the acceleration of the flow field is calculated by the following formula:

[0019]

[0020]

[0021] Among them, a x and a y are the accelerations of the flow field along the x and y directions, respectively, and Δt is 1 / 3 of the time required for the DLP color wheel to make one revolution.

[0022] Furthermore, the flow field measurement area can be changed by changing the opening position of the micromirror array on the DMD chip, which is easy to operate.

[0023] A flow parameter measurement system based on digital light processing technology includes a light source emission module, a light source adjustment module, an image acquisition module and a flow field analysis module;

[0024] The light source emission module emits three primary colors of monochromatic light in sequence, and the duration of each monochromatic light is the same;

[0025] The light source adjustment module adjusts the monochromatic light through the DMD chip to generate a light sheet, which is irradiated on the flow field measurement area and illuminates the tracer particles;

[0026] The image acquisition module uses a color CCD camera with a shooting direction perpendicular to the light sheet to perform long exposure to obtain a color particle image containing three primary colors;

[0027] The flow field analysis module decouples the color particle image to obtain three monochrome particle images, and calculates the three-dimensional velocity field and the three-dimensional acceleration field of the flow field measurement area based on the three monochrome particle images;

[0028] By periodically changing the color of monochromatic light and delaying exposure, a color particle image containing three primary colors is obtained. Based on this color particle image, a three-dimensional velocity field and a three-dimensional acceleration field can be obtained. This can reduce the number of images taken by the camera and improve detection efficiency. At the same time, this method based on optical digital modulation reduces the number of optical components and displacement control devices used in particle image velocimetry technology, greatly reducing costs.

[0029] Digital modulation of light sheets based on the DMD chip can produce light sheets with stable light intensity, uniform distribution, and fixed thickness, with high measurement accuracy.

[0030] Furthermore, the monochromatic light emission process includes:

[0031] The light source emission module irradiates a monochromatic light source onto the DLP color wheel and simultaneously rotates the DLP color wheel at a constant speed to obtain monochromatic light of three primary colors. The monochromatic light of three primary colors can be obtained stably and at high frequency, and has a simple structure and low cost.

[0032] Furthermore, it also includes a synchronization control module, which controls the DLP color wheel and the color CCD camera to run synchronously through a synchronization controller, thereby ensuring detection accuracy and low implementation difficulty.

[0033] Furthermore, the calculation process of the three-dimensional velocity field and the three-dimensional acceleration field of the flow field includes:

[0034] The flow field analysis module obtains a first velocity vector V1=(u1, v1) of the flow field based on the first monochrome particle image and the second monochrome particle image through an image cross-correlation algorithm, where u1 and v1 are the first velocities of the flow field along the x-direction and the y-direction respectively;

[0035] The flow field analysis module obtains a second velocity vector V2=(u2, v2) of the flow field based on the second monochrome particle image and the third monochrome particle image through an image cross-correlation algorithm, where u2 and v2 are the second velocities of the flow field along the x-direction and the y-direction, respectively.

[0036] The flow field analysis module calculates the acceleration of the flow field according to the first velocity and the second velocity using the following formula:

[0037]

[0038]

[0039] Among them, a x and a y are the accelerations of the flow field along the x and y directions, respectively, and Δt is 1 / 3 of the time required for the DLP color wheel to make one revolution.

[0040] Furthermore, the light source adjustment module changes the flow field measurement area by changing the micromirror opening position of the DMD micromirror array, and is easy to operate.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The present invention successively emits monochromatic light of three primary colors, each monochromatic light having the same duration. The monochromatic light is incident on a DMD chip and is adjusted by the DMD chip to generate a sheet light. The sheet light is irradiated on the flow field measurement area and illuminates the tracer particles. A color CCD camera with a shooting direction perpendicular to the sheet light is used for long-term exposure to obtain a color particle image containing the three primary colors. The color particle image is decoupled to obtain three monochromatic particle images. The three-dimensional velocity field and the three-dimensional acceleration field of the flow field measurement area are calculated based on the three monochromatic particle images. By periodically changing the color of the monochromatic light and delaying the exposure, a color particle image containing the three primary colors is obtained. The color particle image contains the flow field information at three different moments. At the same time, the flow field information at three different moments can be obtained by a cross-correlation algorithm. The three-dimensional velocity field and the three-dimensional acceleration field are further calculated, which can reduce the number of images taken by the camera and improve the detection efficiency.

[0043] (2) The present invention is based on optical digital modulation, which reduces the number of optical elements and displacement control devices used in particle image velocimetry technology, greatly reducing costs;

[0044] (3) The present invention uses a DMD chip to perform digital modulation of light sheets, which can produce light sheets with stable light intensity, uniform distribution, and fixed thickness, and has high measurement accuracy;

[0045] (4) The present invention illuminates a monochromatic light source onto a DLP color wheel and simultaneously rotates the DLP color wheel at a constant speed to obtain monochromatic light of three primary colors. This method can obtain monochromatic light of three primary colors stably and at high frequency, has a simple structure, and is low in cost.

[0046] (5) The present invention controls the DLP color wheel and the color CCD camera to operate synchronously through a synchronous controller, thereby ensuring detection accuracy and having low implementation difficulty;

[0047] (6) The present invention changes the flow field measurement area by changing the opening position of the micromirror array on the DMD chip, and the operation is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a structural schematic diagram of the flow parameter measurement device;

[0049] Figure 2 is a color particle image;

[0050] Description of the numbers in the figure:

[0051] 1. DMD chip, 2. Light sheet, 3. Flow field measurement area, 4. Color particle image, 5. Color CCD camera, 6. Synchronous controller, 7. Monochromatic light source, 8. DLP color wheel. DETAILED DESCRIPTION

[0052] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0053] Example 1

[0054] A flow parameter measurement method based on digital light processing technology, such as Figure 1 , based on a flow parameter measurement device, the device includes a DMD chip 1, a color CCD camera 5, a synchronization controller 6 and a DLP color wheel 8;

[0055] Flow parameter measurement methods include:

[0056] The three primary colors of monochromatic light are emitted successively, and the duration of each monochromatic light is the same;

[0057] Monochromatic light is incident on DMD chip 1 and is modulated by DMD chip 1 to generate light sheet 2;

[0058] The light sheet 2 is irradiated on the flow field measurement area 3 and illuminates the tracer particles. A color CCD camera 5 with a shooting direction perpendicular to the light sheet 2 is used for long exposure to obtain a color particle image 4 containing three primary colors.

[0059] Decoupling the color particle image 4 to obtain three monochrome particle images, and calculating the three-dimensional velocity field and the three-dimensional acceleration field of the flow field measurement area 3 based on the three monochrome particle images;

[0060] By periodically changing the color of monochromatic light and delaying the exposure, a color particle image 4 containing three primary colors is obtained. Based on this color particle image 4, a three-dimensional velocity field and a three-dimensional acceleration field can be obtained, which can reduce the number of images taken by the camera and improve the detection efficiency. At the same time, this method based on optical digital modulation reduces the number of optical elements and control displacement devices used in particle image velocimetry technology, greatly reducing costs.

[0061] Digital modulation of light sheet based on DMD chip 1 can produce a light sheet with stable light intensity, uniform distribution, and fixed thickness, with high measurement accuracy. DMD chip 1 adopts the PDC05-50 series DMD chip, whose micromirror array is 1920×1080. The 10 columns of micromirrors at the center are selected with a fixed number of columns of 10, and the number of rows remains unchanged at 1920 rows. The 1920×10 micromirror array is turned on, and the rest are all turned off.

[0062] The calculation process of the three-dimensional velocity field and three-dimensional acceleration field of the flow field includes:

[0063] According to the first monochrome particle image and the second monochrome particle image, the first velocity vector V1=(u1, v1) of the flow field is obtained by image cross-correlation algorithm, where u1 and v1 are the first velocities of the flow field along the x-direction and the y-direction respectively;

[0064] According to the second and third monochrome particle images, the second velocity vector V2 = (u2, v2) of the flow field is obtained by image cross-correlation algorithm, where u2 and v2 are the second velocities of the flow field along the x and y directions, respectively.

[0065] According to the first velocity and the second velocity, the acceleration of the flow field is calculated by the following formula:

[0066]

[0067]

[0068] Among them, a x and a y are the accelerations of the flow field along the x and y directions, respectively, and Δt is 1 / 3 of the time required for the DLP color wheel 8 to make one revolution.

[0069] The flow field measurement area 3 is changed by changing the opening position of the micromirror array on the DMD chip 1, which is easy to operate.

[0070] In recent years, digital light processing (DLP) technology with digital micromirror device (DMD) as the control core has become the most representative product of existing digital light modulation technology.

[0071] The emission process of monochromatic light includes:

[0072] The monochromatic light source 7 is irradiated on the DLP color wheel 8, and the DLP color wheel 8 is rotated at a constant speed to obtain monochromatic light of three primary colors. The monochromatic light of three primary colors can be obtained stably, with a simple structure and low cost.

[0073] The synchronous controller 6 controls the DLP color wheel 8 and the color CCD camera 5 to run synchronously, ensuring detection accuracy and low difficulty. The rotation speed of the DLP color wheel 8 can be adjusted by the synchronous controller 6 to a maximum of 360 revolutions per second. In this embodiment, the exposure time of the color CCD camera 5 is controlled by the synchronous controller 6 to be 0.004s, and a color particle image 4 is captured within the time when the DLP color wheel 8 rotates one circle. Figure 2 As shown, the size of the color particle image 4 is 500 pixels, the rotation speed of the DLP color wheel 8 is 250 revolutions per second, and the time for one revolution is 0.004 seconds.

[0074] Example 2

[0075] A flow parameter measurement system based on digital light processing technology is implemented based on a flow parameter measurement device. The device includes a DMD chip 1, a color CCD camera 5, a synchronization controller 6 and a DLP color wheel 8. The flow parameter measurement system includes a light source emission module, a light source adjustment module, an image acquisition module and a flow field analysis module.

[0076] The light source emission module emits three primary colors of monochromatic light in sequence, and the duration of each monochromatic light is the same;

[0077] The light source adjustment module adjusts the monochromatic light through the DMD chip 1 to generate a light sheet 2. The light sheet 2 is irradiated on the flow field measurement area 3 and illuminates the tracer particles.

[0078] The image acquisition module uses a color CCD camera 5 with a shooting direction perpendicular to the light sheet 2 to perform long exposure to obtain a color particle image 4 containing three primary colors;

[0079] The flow field analysis module decouples the color particle image 4 to obtain three monochrome particle images, and calculates the three-dimensional velocity field and the three-dimensional acceleration field of the flow field measurement area 3 based on the three monochrome particle images;

[0080] By periodically changing the color of monochromatic light and delaying the exposure, a color particle image 4 containing three primary colors is obtained. Based on this color particle image 4, a three-dimensional velocity field and a three-dimensional acceleration field can be obtained, which can reduce the number of images taken by the camera and improve the detection efficiency. At the same time, this method based on optical digital modulation reduces the number of optical elements and control displacement devices used in particle image velocimetry technology, greatly reducing costs.

[0081] Digital modulation of the light sheet based on the DMD chip 1 can generate a light sheet with stable light intensity, uniform distribution, and fixed thickness, and has high measurement accuracy.

[0082] The emission process of monochromatic light includes:

[0083] The light source emitting module irradiates the monochromatic light source 7 onto the DLP color wheel 8 and simultaneously rotates the DLP color wheel 8 at a constant speed to obtain monochromatic light of three primary colors. The monochromatic light of three primary colors can be obtained stably with a simple structure and low cost.

[0084] It also includes a synchronization control module, which controls the DLP color wheel 8 and the color CCD camera 5 to run synchronously through the synchronization controller 6, thereby ensuring detection accuracy and low implementation difficulty.

[0085] The calculation process of the three-dimensional velocity field and three-dimensional acceleration field of the flow field includes:

[0086] The flow field analysis module obtains the first velocity vector V1 = (u1, v1) of the flow field based on the first monochrome particle image and the second monochrome particle image through the image cross-correlation algorithm, where u1 and v1 are the first velocities of the flow field along the x-direction and the y-direction respectively;

[0087] The flow field analysis module obtains the second velocity vector V2 = (u2, v2) of the flow field based on the second monochrome particle image and the third monochrome particle image through the image cross-correlation algorithm, where u2 and v2 are the second velocities of the flow field along the x-direction and the y-direction respectively;

[0088] The flow field analysis module calculates the acceleration of the flow field based on the first velocity and the second velocity using the following formula:

[0089]

[0090]

[0091] Among them, a x and a y are the accelerations of the flow field along the x and y directions, respectively, and Δt is 1 / 3 of the time required for the DLP color wheel 8 to make one revolution.

[0092] The light source adjustment module changes the flow field measurement area 3 by changing the micromirror opening position of the DMD micromirror array, and the operation is simple.

[0093] Examples 1 and 2 propose a flow parameter measurement method and system based on digital light processing technology. By periodically changing the color of monochromatic light and delaying exposure, a color particle image 4 containing three primary colors is obtained. Based on a color particle image 4, a three-dimensional velocity field and a three-dimensional acceleration field can be obtained, which can reduce the number of images taken by the camera and improve detection efficiency. At the same time, this method based on optical digital modulation reduces the number of optical elements and control displacement devices used in particle image velocimetry technology, greatly reducing costs. Digital modulation of light sheets based on the DMD chip 1 can generate light sheets with stable light intensity, uniform distribution, and fixed thickness, and high measurement accuracy.

[0094] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A flow parameter measurement method based on digital light processing technology, characterized in that: include: The three primary colors of monochromatic light are emitted successively, and the duration of each monochromatic light is the same; The monochromatic light is incident on the DMD chip and is regulated by the DMD chip to generate a sheet light; The light sheet is irradiated on the flow field measurement area and illuminates the tracer particles. A color CCD camera with a shooting direction perpendicular to the light sheet is used for long exposure to obtain a color particle image containing three primary colors. The color particle image is decoupled to obtain three monochrome particle images. The three-dimensional velocity field and three-dimensional acceleration field of the flow field measurement area are calculated based on the three monochrome particle images. The calculation process of the three-dimensional velocity field and the three-dimensional acceleration field of the flow field includes: According to the first monochrome particle image and the second monochrome particle image, the first velocity vector of the flow field is obtained by the image cross-correlation algorithm. , and Flow field along x Direction and y First velocity in direction; According to the second monochrome particle image and the third monochrome particle image, the second velocity vector of the flow field is obtained by the image cross-correlation algorithm. , and Flow field along x Direction and y Second speed of direction; According to the first velocity and the second velocity, the acceleration of the flow field is calculated by the following formula: in, and Flow field along x Direction and y The acceleration in the direction It is 1 / 3 of the time required for the DLP color wheel to make one rotation.

2. The method for measuring flow parameters based on digital light processing technology according to claim 1, characterized in that: The monochromatic light emission process includes: Irradiate a monochromatic light source onto the DLP color wheel while rotating the DLP color wheel at a constant speed to obtain monochromatic light of the three primary colors.

3. The method for measuring flow parameters based on digital light processing technology according to claim 2, characterized in that: The DLP color wheel and color CCD camera are controlled to run synchronously through a synchronous controller.

4. The method for measuring flow parameters based on digital light processing technology according to claim 1, characterized in that: By changing the opening position of the micromirror array on the DMD chip, the flow field measurement area is changed.

5. A flow parameter measurement system based on digital light processing technology, characterized in that: include: The light source emission module is used to emit three primary colors of monochromatic light in sequence, with each monochromatic light having the same duration; A light source adjustment module is used to adjust the monochromatic light through the DMD chip to generate a light sheet, which is irradiated on the flow field measurement area and illuminates the tracer particles; An image acquisition module is used to obtain a color particle image containing three primary colors by using a color CCD camera with a shooting direction perpendicular to the light sheet for a long exposure; The flow field analysis module is used to decouple the color particle image and obtain three monochrome particle images. The three-dimensional velocity field and three-dimensional acceleration field of the flow field measurement area are calculated based on the three monochrome particle images. The calculation process of the three-dimensional velocity field and the three-dimensional acceleration field of the flow field includes: The flow field analysis module obtains the first velocity vector of the flow field through the image cross-correlation algorithm based on the first monochrome particle image and the second monochrome particle image. , and Flow field along x Direction and y First velocity in direction; The flow field analysis module obtains the second velocity vector of the flow field through the image cross-correlation algorithm based on the second monochrome particle image and the third monochrome particle image. , and Flow field along x Direction and y Second speed of direction; The flow field analysis module calculates the acceleration of the flow field according to the first velocity and the second velocity using the following formula: in, and Flow field along x Direction and y The acceleration in the direction It is 1 / 3 of the time required for the DLP color wheel to make one rotation.

6. The flow parameter measurement system based on digital light processing technology according to claim 5, characterized in that: The monochromatic light emission process includes: The light source emission module irradiates the monochromatic light source onto the DLP color wheel and simultaneously rotates the DLP color wheel at a constant speed to obtain monochromatic light of three primary colors.

7. The flow parameter measurement system based on digital light processing technology according to claim 6, characterized in that: It also includes a synchronization control module, which controls the DLP color wheel and the color CCD camera to run synchronously through a synchronization controller.

8. The flow parameter measurement system based on digital light processing technology according to claim 5, characterized in that: The light source adjustment module changes the flow field measurement area by changing the micromirror opening position of the DMD micromirror array.

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