A system capable of simultaneously measuring combustion temperature field and velocity field

Abstract

The present invention relates to a system capable of realizing simultaneous measurement of combustion temperature field and velocity field, comprising a first CCD camera, a first spectroscopic wedge and a laser, wherein a second CCD camera is arranged at the lower left of the first CCD camera, and an imaging screen is installed at the right side of the second CCD camera, a Ronchi grating is arranged at the right side of the imaging screen, and a first plane reflector is installed at the right side of the Ronchi grating, a second spectroscopic wedge is arranged below the first spectroscopic wedge, and the first spectroscopic wedge is located below the second plane reflector, a laser is installed at the right side of the synchronization controller, and the synchronization controller is located below the second CCD camera. The system combines particle imaging technology (PIV) with the principle of light deflection imaging, uses particle imaging technology to measure the three-dimensional velocity field of the flow field, and uses the principle of light deflection imaging to measure the three-dimensional temperature field of the flow field, and the combination of the two simultaneously obtains the three-dimensional velocity field and temperature field of the combustion field.

Description

Technical Field

[0001] The invention relates to the field of measurement technology, and in particular to a system capable of realizing simultaneous measurement of a combustion temperature field and a velocity field. Background Art

[0002] The full-field display and measurement of combustion flow fields is a hot issue that has not been completely resolved in the fields of engineering thermal physics and information optics. Its research frontier has extended to the development of new technologies for synchronous measurement and visualization of multi-parameter distribution of complex combustion flow fields. Point measurement technology can be used for simple laminar flame parameter measurement, including the use of laser-induced grating spectroscopy, coherent anti-Stokes Raman scattering, two-line atomic fluorescence and other technologies to measure temperature, the use of laser Doppler velocimetry technology to perform point measurement of local velocity, the use of tunable semiconductor laser absorption spectroscopy technology to obtain concentration and temperature, and the use of cavity enhancement technology to detect trace flame components. However, modern three-dimensional simultaneous measurement and display technology for the temperature field and velocity field of combustion flow fields is rare, and the measurement of temperature field and velocity field has the problems of high cost, time-consuming and low efficiency. For this reason, we propose a system that can realize the simultaneous measurement of combustion temperature field and velocity field. Summary of the invention

[0003] The purpose of the present invention is to provide a system that can realize the simultaneous measurement of combustion temperature field and velocity field, so as to solve the problems raised in the above background technology that there are few modern three-dimensional simultaneous measurement and display technologies for the temperature field and velocity field of the combustion flow field, and the measurement of the temperature field and velocity field is high in cost, time-consuming and low in efficiency.

[0004] To achieve the above-mentioned object, the present invention provides the following technical solution: a system capable of realizing simultaneous measurement of combustion temperature field and velocity field, comprising a first CCD camera, a first spectroscopic wedge and a laser, wherein a second CCD camera is arranged at the lower left of the first CCD camera, and an imaging screen is installed at the right side of the second CCD camera, a Ronchi grating is arranged at the right side of the imaging screen, and a first plane reflector is installed at the right side of the Ronchi grating, a second plane reflector is arranged at the right side of the first plane reflector, a second spectroscopic wedge is arranged below the first spectroscopic wedge, and the first spectroscopic wedge is located at the second plane reflector. A first CCD camera is connected to a synchronous controller via a communication line, a laser is installed on the right side of the synchronous controller, and the synchronous controller is located below the second CCD camera, a host is arranged below the laser, a signal line is installed on the right side of the host, and a computer is arranged on the right side of the signal line.

[0005] Preferably, three first CCD cameras are provided in total, and the specifications of the first CCD cameras are equal to those of the second CCD cameras.

[0006] Preferably, the optical path angle between the fourth beam splitting wedge and the first beam splitting wedge is 108°, and the optical path angle between the fourth beam splitting wedge and the second plane reflector is 144°.

[0007] Preferably, the optical path angle between the fourth beam splitting wedge and the third beam splitting wedge is 36°, and the optical path angle between the fourth beam splitting wedge and the second beam splitting wedge is 72°.

[0008] Preferably, the first plane reflectors are distributed in a zigzag shape on the left side of the measured flow field, and the first plane reflectors are of equal size.

[0009] Preferably, the first beam splitter wedge, the second beam splitter wedge, the third beam splitter wedge and the fourth beam splitter wedge are equal in size and are distributed in an "L" shape on the right side of the measured flow field.

[0010] Preferably, the synchronization controller is electrically connected to the laser and the host through wires, and the laser and the host are not related to each other.

[0011] In the temperature field reconstruction process, the measured field is discretized into a grid, and the partial derivative calculation formula of the regional refractive index is derived, and then the nonlinear projection is converted into a set of linear algebraic equations. Accurate boundary information can significantly improve the reconstruction accuracy and speed, integrate the prior distribution constraint CS reconstruction, and establish a reconstruction algorithm model combined with boundary detection

[0012]

[0013] Where n is the refractive index distribution to be reconstructed, α||Φn||1 is the regularization term, is the weighted anisotropic total variation, F p is the coefficient matrix related to the light path, and b is the projection information sampling. For the combustion flow field, the flame boundary is connected by discrete points with the largest refractive index gradient. Each reconstruction iteration alternately performs anisotropic total variation and boundary detection for correction, thereby obtaining a reconstructed refractive index distribution that meets the iteration termination criterion, and then obtains the density and temperature distribution by the Glaston-Dyer formula and the flow state equation.

[0014] The beneficial effects of the present invention are:

[0015] The present invention combines particle imaging technology (PIV) with the principle of light deflection imaging, uses particle imaging technology to measure the three-dimensional velocity field of the flow field, and uses the principle of light deflection imaging to measure the three-dimensional temperature field of the flow field. The two are combined to obtain the three-dimensional velocity field and temperature field of the combustion field. The first CCD camera shoots the combustion field, and combined with the INSIGHT4G processing system to obtain the three-dimensional velocity information of the combustion field. The second CCD camera shoots four moiré fringes after splitting and combines the light deflection CT reconstruction technology to obtain the three-dimensional temperature field of the combustion field. The different optical path angles between the fourth splitting wedge and the second plane reflector, the first splitting wedge, the second splitting wedge and the third splitting wedge can refract the light path, and a beam of laser light source is divided into four beams, which pass through the measured flow field. The three splitting wedges, namely the first splitting wedge, the second splitting wedge and the third splitting wedge, form a four-way probe. The measuring light beam forms a precisely controllable multi-angle detection light beam by changing the direction of each light beam, passes through the measured flow field, and passes through the spatial arrangement and combination of the first plane reflector and the second plane reflector. The laser light beam carrying the flow field information of different viewing angles is modulated into a parallel light beam, and forms a moiré fringe pattern on the imaging screen after passing through the perpendicular Ronchi grating. The spatial arrangement and combination of the first splitter wedge, the second splitter wedge, the third splitter wedge and the fourth splitter wedge disperses the light path and passes through the measured flow field at various angles, so that 4 groups of images are finally formed on the imaging screen. With the help of a synchronous controller, the particle imaging and the fringe pattern are synchronously sampled (three first CCD cameras and one second CCD camera operate at the same time). For the common and important axisymmetric flame in the combustion field, the optical deflection CT uses a single light path at any viewing angle to detect the flow field to generate moiré fringes to meet the sampling requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the present invention;

[0017] Figure 2 It is a schematic diagram of the working process of the present invention.

[0018] In the figure: 1. first CCD camera, 2. second CCD camera, 3. imaging screen, 4. Ronchi grating, 5. first plane reflector, 6. second plane reflector, 7. first beam splitter wedge, 8. second beam splitter wedge, 9. third beam splitter wedge, 10. lens, 11. fourth beam splitter wedge, 12. cylindrical lens group, 13. measured flow field, 14. synchronization controller, 15. laser, 16. host, 17. wires, 18. computer. DETAILED DESCRIPTION

[0019] 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.

[0020] See also Figure 1-2The present invention provides a technical solution: a system capable of simultaneously measuring the combustion temperature field and velocity field, comprising a first CCD camera 1, a first spectroscopic wedge 7 and a laser 15, a second CCD camera 2 is arranged at the lower left of the first CCD camera 1, and an imaging screen 3 is installed at the right side of the second CCD camera 2, a total of three first CCD cameras 1 are arranged, and the specifications of the first CCD camera 1 and the second CCD camera 2 are equal, the first CCD camera 1 shoots the combustion field, and combines with INSIGHT The 4G processing system can obtain the three-dimensional velocity information of the combustion field, and the second CCD camera 2 is used to shoot the four moiré fringes after the splitting and the three-dimensional temperature field of the combustion field is obtained by combining the light deflection CT reconstruction technology. A Ronchi grating 4 is arranged on the right side of the imaging screen 3, and a first plane reflector 5 is installed on the right side of the Ronchi grating 4, and a second plane reflector 6 is arranged on the right side of the first plane reflector 5. A second splitter wedge 8 is arranged below the first splitter wedge 7, and the first splitter wedge 7 is located below the second plane reflector 6. A third splitter wedge 9 is installed below the second splitter wedge 8, and a third splitter wedge 9 is fixed on the left side of the third splitter wedge 9. The lens 10 is provided with a fourth beam splitter wedge 11 on the left side of the lens 10, the optical path angle between the fourth beam splitter wedge 11 and the first beam splitter wedge 7 is 108°, the optical path angle between the fourth beam splitter wedge 11 and the second plane reflector 6 is 144°, the optical path angle between the fourth beam splitter wedge 11 and the third beam splitter wedge 9 is 36°, and the optical path angle between the fourth beam splitter wedge 11 and the second beam splitter wedge 8 is 72°. The different optical path angles between the fourth beam splitter wedge 11 and the second plane reflector 6, the first beam splitter wedge 7, the second beam splitter wedge 8 and the third beam splitter wedge 9 can refract the optical path, and a A laser light source is divided into four beams, which pass through the measured flow field 13. The three beam splitting wedges, namely the first beam splitting wedge 7, the second beam splitting wedge 8 and the third beam splitting wedge 9, form four detection beams. By changing the direction of each beam, a precisely controllable multi-angle detection beam passes through the measured flow field 13. A cylindrical lens group 12 is installed above the fourth beam splitting wedge 11, and the measured flow field 13 is arranged above the cylindrical lens group 12. The first plane reflectors 5 are distributed in a zigzag shape on the left side of the measured flow field 13, and the first plane reflectors 5 are equal in size. Through the spatial arrangement and combination of the first plane reflectors 5 and the second plane reflectors 6, the measured flow field 13 is carried. The laser beam with flow field information at different viewing angles is modulated into a parallel beam, and after passing through the perpendicular Ronchi grating 4, a moiré fringe array is formed on the imaging screen 3. The first beam splitter wedge 7, the second beam splitter wedge 8, the third beam splitter wedge 9 and the fourth beam splitter wedge 11 are equal in size, and the first beam splitter wedge 7, the second beam splitter wedge 8, the third beam splitter wedge 9 and the fourth beam splitter wedge 11 are distributed in an "L" shape on the right side of the measured flow field 13. The spatial arrangement and combination of the first beam splitter wedge 7, the second beam splitter wedge 8, the third beam splitter wedge 9 and the fourth beam splitter wedge 11 disperses the optical path and passes through the measured flow field 13 at various angles.Finally, four groups of images are formed on the imaging screen 3. A laser 15 is installed on the right side of the synchronous controller 14, and the synchronous controller 14 is located below the second CCD camera 2. A host 16 is arranged below the laser 15, and a wire 17 is installed on the right side of the host 16. The synchronous controller 14 is electrically connected to the laser 15 and the host 16 through the wire 17, and the laser 15 and the host 16 are not related to each other. With the help of the synchronous controller 14, the particle imaging and the fringe pattern array are synchronously sampled (three first CCD cameras 1 and one second CCD camera 2 operate simultaneously). For the common and important axisymmetric flame in the combustion field, the optical deflection CT uses any single optical path to detect the flow field to generate moiré fringes to meet the sampling requirements. A computer 18 is arranged on the right side of the wire 17.

[0021] Working principle: For this type of system that can realize the simultaneous measurement of combustion temperature field and velocity field, the laser (532nm) emitted by the laser 15 (Nd:YAG) is first divided into two laser beams with equal energy, one of which is modulated into a cone beam by the cylindrical lens group 12 for V3V imaging, and the particle image is collected by three first CCD cameras 1 (2352 pixels × 1768 pixels). The principle and idea of ​​"controlling the reflector array to modulate spatial light" of the digital micromirror device is used to construct a new light deflection CT sampling method: the other laser beam after splitting is expanded and collimated, and then four detection beams are formed by the three spectroscopic wedges of the first spectroscopic wedge 7, the second spectroscopic wedge 8 and the third spectroscopic wedge 9. By changing the direction of each beam, a precisely controllable multi-angle detection beam is formed, which passes through the measured flow field 13 and passes through the first plane reflector 5 and the second plane reflector 6. The laser beam carrying the flow field information of different viewing angles is modulated into a parallel beam through spatial arrangement and combination. After passing through the perpendicular Ronchi grating 4, a moiré fringe pattern is formed on the imaging screen 3, and a second CCD camera 2 (2352 pixels × 1768 pixels) performs dynamic sampling. The optical deflection imaging system overcomes the defects of the existing multi-(divided) optical path system, which requires multiple imaging elements and multiple CCD camera devices, and is difficult to ensure strict replication of the optical path. It completes instant 4-direction projection ordered array imaging on a single CCD image. With the help of the synchronous controller 14 (SYNC), the particle imaging and the fringe pattern are synchronously sampled (the four CCD cameras act simultaneously). For the common and important axisymmetric flames in the combustion field, the optical deflection CT uses a single optical path at any viewing angle to detect the flow field to generate moiré fringes to meet the sampling requirements. The image analysis uses the advanced INSIGHT The 4G processing system uses a pipeline processing algorithm to obtain complete information about the fluid structure, including average velocity, vorticity, turbulence information, high-order derivatives, and high-order statistical values. The reconstruction of the three-dimensional temperature field has two steps. First, the fringe information containing high-intensity noise is extracted. From the analysis of the cause of the noise and the noise intensity, the noise of the electronic speckle pattern interferometry (ESPI) fringe pattern is very similar to the noise of the moiré fringe pattern caused by the tracer particles. Drawing on the denoising theory of the ESPI fringe pattern and utilizing the directionality of the fringe pattern, a moiré fringe spin filtering method based on fuzzy directions is adopted to define four fuzzy directions in the neighborhood of the current point. Window, transform the determination of the one-dimensional, precise direction window of the classical spin filter into the determination of the fuzzy direction window. When performing low-pass filtering in the determined window, an adaptive weighted mean filter is used instead of the traditional median filter. The deflection information of the denoised fringe image is extracted based on fringe tracking and displacement analysis. Then, the temperature field is reconstructed, the field to be measured is discretized into a grid, and the partial derivative calculation formula represented by the regional refractive index is derived, and then the nonlinear projection is converted into a set of linear algebraic equations. Accurate boundary information can significantly improve the reconstruction accuracy and speed. The prior distribution constraint CS reconstruction is integrated to establish a reconstruction algorithm model combined with boundary detection: Where n is the refractive index distribution to be reconstructed, α||Φn||1 is the regularization term, is the weighted anisotropic total variation, F p is the coefficient matrix related to the light path, b is the projection information sampling, for the combustion flow field, the flame boundary is connected by discrete points with the largest refractive index gradient, and each reconstruction iteration alternately performs anisotropic total variation and boundary detection for correction, so as to obtain a reconstructed refractive index distribution that meets the iteration termination criterion, and then the density and temperature distribution are obtained by the Glaston-Dyer formula and the flow state equation. In this method, the particle imaging technology (PIV) is combined with the principle of light deflection imaging to measure the velocity field and temperature field of the combustion flow field. Compared with the microfluid three-dimensional velocity field and temperature field measurement method in which the MicroHPTV system is combined with the LIP system to measure the velocity field and temperature field, it is more economical, can measure conventional scales as well as microscales, and has the advantages of non-contact, three-dimensional, and simultaneous measurement and display of velocity field and temperature field.

[0022] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system capable of simultaneously measuring a combustion temperature field and a velocity field, comprising a first CCD camera (1), a first beam splitting wedge (7) and a laser (15), characterized in that: A second CCD camera (2) is arranged at the lower left of the first CCD camera (1); an imaging screen (3) is installed on the right side of the second CCD camera (2); a Ronchi grating (4) is arranged on the right side of the imaging screen (3); a first plane reflector (5) is installed on the right side of the Ronchi grating (4); a second plane reflector (6) is arranged on the right side of the first plane reflector (5); a second beam splitter wedge (8) is arranged below the first beam splitter wedge (7); the first beam splitter wedge (7) is located below the second plane reflector (6); a third beam splitter wedge (9) is installed below the second beam splitter wedge (8); a lens is fixed on the left side of the third beam splitter wedge (9); (10), a fourth beam splitter wedge (11) is arranged on the left side of the lens (10), a cylindrical lens group (12) is installed above the fourth beam splitter wedge (11), a measured flow field (13) is arranged above the cylindrical lens group (12), a first CCD camera (1) is connected to a synchronous controller (14) via a communication line, a laser (15) is installed on the right side of the synchronous controller (14), the synchronous controller (14) is located below the second CCD camera (2), a host (16) is arranged below the laser (15), a signal line (17) is installed on the right side of the host (16), and a computer (18) is arranged on the right side of the signal line (17).

2. The system capable of simultaneously measuring the combustion temperature field and the velocity field according to claim 1, characterized in that: A total of three first CCD cameras (1) are provided, and the specifications of the first CCD cameras (1) and the second CCD cameras (2) are equal.

3. The system capable of simultaneously measuring combustion temperature field and velocity field according to claim 1, characterized in that: The optical path angle between the fourth beam splitting wedge (11) and the first beam splitting wedge (7) is 108°, and the optical path angle between the fourth beam splitting wedge (11) and the second plane reflector (6) is 144°.

4. The system capable of simultaneously measuring combustion temperature field and velocity field according to claim 1, characterized in that: The optical path angle between the fourth beam splitting wedge (11) and the third beam splitting wedge (9) is 36 degrees, and the optical path angle between the fourth beam splitting wedge (11) and the second beam splitting wedge (8) is 72 degrees.

5. The system capable of simultaneously measuring combustion temperature field and velocity field according to claim 1, characterized in that: The first plane reflectors (5) are distributed in a zigzag shape on the left side of the measured flow field (13), and the first plane reflectors (5) are of equal size.

6. The system capable of simultaneously measuring combustion temperature field and velocity field according to claim 1, characterized in that: The first beam splitter wedge (7), the second beam splitter wedge (8), the third beam splitter wedge (9) and the fourth beam splitter wedge (11) are of equal size, and are distributed in an "L" shape on the right side of the measured flow field (13).

7. The system capable of simultaneously measuring combustion temperature field and velocity field according to claim 1, characterized in that: The synchronous controller (14) is electrically connected to the laser (15) and the host (16) via a wire (17), and the laser (15) and the host (16) are not related to each other.

8. The system for simultaneously measuring the combustion temperature field and the velocity field according to any one of claims 1 to 7, characterized in that: The reconstruction algorithm model combined with boundary detection is: Where n is the refractive index distribution to be reconstructed, α||Φn||1 is the regularization term, is the weighted anisotropic total variation, F p is the coefficient matrix related to the light path, and b is the projection information sampling.

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