A mixed combustion process simultaneous visualization device and detection method

Abstract

A mixed combustion process simultaneous visualization device and detection method, relating to the technical field of multi-field and multi-parameter synchronous visualization for energy and power devices. An acetone generator is set on the gas supply pipeline of the combustion device, and two laser systems are arranged on both sides of the combustion device. The laser is output by arranging a frequency doubling. Two sets of structured light modulation shaping systems are arranged between the laser system and the combustion device, and aperture diaphragms, beam expanders, gratings, collimators and focusing lenses are arranged in sequence. The gratings select different numbers of engraved lines, and the ICMOS camera is equipped with a bandpass filter corresponding to the combustion field. The PLIF image is generated by a computer, and the trigger controls two digital signal generators to realize the synchronous signal control of the PLIF system and the two laser systems. Based on the idea of ​​spatial structured light modulation, through the encoding and decoding of information, one ICMOS camera can realize the simultaneous visualization of three components, which is simple and reasonable, and helps to save costs and improve efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-field and multi-parameter synchronous visualization of energy and power devices, and in particular to a simultaneous visualization device and detection method for a mixed combustion process. Background Art

[0002] The design focus of aircraft engines is to improve the performance of the engine itself, so that the fuel in the engine combustion chamber burns more fully, so as to improve the combustion efficiency of the fuel while reducing pollutant emissions. The fuel combustion process of the engine is divided into injection, atomization, evaporation, mixing, combustion and other processes. The quality of the fuel and oxidant mixing and combustion process directly affects the ignition process, flame propagation speed, combustion stability and fuel combustion efficiency, and even further affects the performance and reliability of the combustion device. Therefore, studying the mixing and combustion process of the engine is an effective means to understand its working performance in detail.

[0003] Planar Laser-induced Fluorescence (PLIF) is a cutting-edge optical measurement technology in the field of combustion diagnosis. It has high temporal and spatial resolution and high sensitivity, and can achieve multi-component synchronous measurement. However, for the synchronous measurement of multiple components, multiple lasers and detection equipment are required. In addition, in the study of mixing and combustion processes, acetone molecules can be used to characterize the flow field structure of the unburned area, the distribution of the combustion intermediate product OH radicals can characterize the burnout zone, and the combustion intermediate product CH radicals can characterize the combustion reaction zone. Therefore, the simultaneous excitation of acetone molecules and OH / CH radicals can be used to deeply analyze the engine mixing and combustion process. However, the simultaneous visualization of mixing and combustion processes often requires multiple lasers and detectors. For example, acetone molecules are usually measured with a 266nm laser, OH radicals are usually measured with a 283nm laser, and CH radicals are usually measured with a 310nm laser. Three lasers and detection equipment are required to work simultaneously, which not only makes the system complex, but also leads to high costs.

[0004] Therefore, considering the excitation and detection strategies and applying the advanced structured light coding concept, a small amount of equipment is used to simultaneously excite acetone molecules, OH radicals and CH radicals on the basis of reducing the experimental equipment and system complexity, so as to realize the instantaneous measurement and visualization of the flame structure in the flame reaction zone, burnout zone and fuel distribution area, which is of great significance for analyzing the mixed combustion process, improving the detection efficiency and controlling the experimental cost. Summary of the invention

[0005] In order to overcome the shortcomings of the background technology, the present invention provides a device and a detection method for simultaneous visualization of a mixed combustion process. The device is based on the idea of ​​spatial structured light modulation and can realize simultaneous visualization of three components by encoding and decoding information using an ICMOS camera. The method is simple and reasonable and helps to save costs and improve efficiency.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A mixed combustion process simultaneous visualization device comprises a combustion device, a timing control system, a PLIF system, two laser systems and two structured light modulation shaping systems, wherein the combustion device is connected with a gas supply pipeline and an air supply pipeline, an acetone generating device is arranged on the gas supply pipeline, the two laser systems are respectively arranged on both sides of the combustion device to emit two laser beams, and the output ends of the two laser systems are respectively arranged with a first frequency doubling and a second frequency doubling so that the two laser beams are output as 310.690nm laser and 283.553nm laser, respectively, the two structured light modulation shaping systems are respectively arranged between the two laser systems and the combustion device, and the structured light modulation shaping systems are sequentially arranged with an aperture stop and a beam expander along the laser path direction. , gratings, collimators and focusing lenses, so that the two laser beams are modulated and shaped into sheet light and then co-focally arranged with the combustion field of the combustion device, wherein the gratings of the two sets of structured light modulation and shaping systems select different numbers of engraved lines to make the two laser beams have different modulation periods, the PLIF system includes an ICMOS camera and a computer, the ICMOS camera is equipped with a bandpass filter and is arranged corresponding to the combustion field of the combustion device, and simultaneously captures the fluorescence radiated by acetone molecules, CH free radicals and OH free radicals and generates the collected PLIF images through the computer, the timing control system includes a trigger and two digital signal generators, the trigger controls the two digital signal generators to realize synchronous signal control of the PLIF system and the two laser systems.

[0008] Furthermore, flow meters are respectively provided on the gas supply pipeline and the air supply pipeline.

[0009] Furthermore, the two laser systems are both composed of a solid laser and a dye laser. The solid laser is used to emit laser light, and the dye laser changes the laser light into different colors for differentiation.

[0010] Furthermore, the first frequency doubling output end and the second frequency doubling output end are respectively provided with a reflector group to introduce the 310.690nm laser and the 283.553nm laser into the corresponding structured light modulation and shaping system.

[0011] A method for simultaneously visualizing and detecting a mixed combustion process comprises the following steps:

[0012] Step 1: Construction and debugging of laser system

[0013] Two laser systems were built and debugged on both sides of the combustion device. One of the laser systems outputted 310.690nm laser through the first frequency doubling to excite CH free radicals, and the other laser system outputted 283.553nm laser through the second frequency doubling to simultaneously excite acetone molecules and OH free radicals.

[0014] Step 2: Construction of structured light modulation shaping system and information encoding

[0015] Two sets of structured light modulation and shaping systems are built between the two sets of laser systems and the combustion device, so that the 310.690nm laser and the 283.553nm laser pass through the two sets of structured light modulation and shaping systems respectively, and after being modulated and shaped into sheet light, they are incident on the same position of the combustion field of the combustion device, encoding OH radicals / acetone molecules and CH radicals at the same spatial position;

[0016] Step 3: Construction of acetone generator and combustion device

[0017] Connect the gas supply pipeline to the acetone generator, connect the acetone generator and the air supply pipeline to the combustion device, and organize the gas in the combustion device to burn;

[0018] Step 4: Construction of timing control system

[0019] The two digital signal generators are controlled by triggers to synchronize the signal control between the two laser systems and the PLIF system;

[0020] Step 5: Build the PLIF system and decode the information

[0021] The fluorescence information of acetone molecules, OH free radicals and CH free radicals is collected simultaneously by an ICMOS camera equipped with a bandpass filter. The information of acetone molecules and OH free radicals is distinguished by spatial position, and the fluorescence information is demodulated by a multiple exposure frequency recognition algorithm.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: based on the idea of ​​spatial structured light modulation, the present invention overcomes the drawback that the traditional mixed combustion process visualization research needs to use multiple sets of excitation detection equipment, and uses two sets of laser systems and structured light modulation shaping systems combined with an ICMOS camera for detection. Through the encoding and decoding of information, the three components of acetone molecules, OH free radicals and CH free radicals can be simultaneously visualized, which can be used to deeply analyze the mixed combustion process and analyze the laws of complex turbulent combustion. In addition, the structure is simpler and more reasonable, which helps to save costs and improve efficiency, and is of great significance for understanding the mixed combustion mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1It is a schematic diagram of the principle of the device for simultaneously visualizing the mixed combustion process of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, a device for simultaneously visualizing a mixed combustion process includes a combustion device 1, a timing control system, a PLIF system, two laser systems, and two structured light modulation and shaping systems.

[0026] The combustion device 1 is connected to a gas supply pipeline 1-1 and an air supply pipeline 1-2, and an acetone generator 1-3 is arranged on the gas supply pipeline 1-1 to ensure that the gas is fully mixed with acetone before entering the combustion device 1. Flow meters can be arranged on the gas supply pipeline 1-1 and the air supply pipeline 1-2 to monitor the flow of gas and air. By constructing the acetone generator 1-3 and the combustion device 1, the gas carrying acetone molecules can be obtained through the acetone generator 1-3 by the bubbling method and introduced into the combustion device 1. After the flame is ignited, the three components are measured by PLIF through the ICMOS camera 12 of the PLIF system, so as to realize the simultaneous visualization of the mixed combustion process.

[0027] The two laser systems are respectively arranged on both sides of the combustion device 1 to emit two laser beams. Both laser systems are composed of a solid laser 2 and a dye laser 3. The solid laser 2 is used to emit laser light, and the dye laser 3 changes the laser light into different colors, so that the two laser beams can be distinguished. The first frequency doubling 4 and the second frequency doubling 5 are respectively arranged at the output ends of the two laser systems so that the two laser beams are output as 310.690nm laser light and 283.553nm laser light respectively. The excitation and detection of CH-PLIF are realized by the 310.690nm laser light, and the simultaneous excitation and detection of acetone and OH-PLIF are realized by the 283.553nm laser light, wherein the acetone molecules and OH free radicals are distinguished by the different spatial positions, and the acetone molecules are closer to the outlet of the combustion device 1.

[0028] The two sets of structured light modulation shaping systems are respectively arranged between the two sets of laser systems and the combustion device 1, and a reflector group 6 can be respectively arranged at the output ends of the first frequency doubling 4 and the second frequency doubling 5 to introduce 310.690nm and 283.553nm lasers into the corresponding structured light modulation shaping systems. The structured light modulation shaping system is sequentially arranged with an aperture diaphragm 7, a beam expander 8, a grating 9, a collimator 10 and a focusing lens 11 along the laser path direction, so that the two laser beams are modulated and shaped into sheet light and then confocally arranged with the combustion field of the combustion device 1. Among them, the grating 9 of the two sets of structured light modulation shaping systems selects different numbers of grating lines so that the two laser beams have different modulation periods, so as to encode the three components of acetone molecules, OH radicals and CH radicals. The PLIF system includes an ICMOS camera 12 and a computer. The ICMOS camera 12 is equipped with a bandpass filter and is arranged corresponding to the combustion field of the combustion device 1, and simultaneously captures the fluorescence radiated by the acetone molecules, CH radicals and OH radicals and generates the collected PLIF images through the computer. The timing control system includes a trigger 14 and two digital signal generators 13. The trigger 14 controls the two digital signal generators 13 to realize synchronous signal control of the PLIF system and the two laser systems.

[0029] like Figure 1 As shown, a method for simultaneously visualizing and detecting a mixed combustion process comprises the following steps:

[0030] Step 1: Construction and debugging of laser system

[0031] Two laser systems are built and debugged on both sides of the combustion device 1, one of which outputs 310.690nm laser through the first frequency doubling 4 to excite CH free radicals, and the other laser system outputs 283.553nm laser through the second frequency doubling 5 to simultaneously excite acetone molecules and OH free radicals. To further distinguish the two laser beams, the two laser systems are composed of a solid laser 2 and a dye laser 3. The solid laser 2 can be a Nd:YAG laser, and the Nd:YAG laser outputs a 532nm laser to pump the dye laser 3, and the two laser beams are changed into different colors by the two different dye lasers 3.

[0032] Step 2: Construction of structured light modulation shaping system and information encoding

[0033] Two sets of structured light modulation and shaping systems are built between the two sets of laser systems and the combustion device 1, so that the 310.690nm laser and the 283.553nm laser pass through the two sets of structured light modulation and shaping systems respectively, and after being modulated and shaped into sheet light, they are incident on the same position of the combustion field of the combustion device 1, and the OH free radicals / acetone molecules and CH free radicals are encoded at the same spatial position;

[0034] Step 3: Construction of acetone generator and combustion device

[0035] Connect the gas supply pipeline 1-1 to the acetone generator 1-3, connect the acetone generator 1-3 and the air supply pipeline 1-2 to the combustion device 1, and organize the gas in the combustion device 1 to burn;

[0036] Step 4: Construction of timing control system

[0037] The two digital signal generators 13 are controlled by the trigger 14 so that the two laser systems and the PLIF system can be synchronously controlled by signals;

[0038] Step 5: Build the PLIF system and decode the information

[0039] The fluorescence information of acetone molecules, OH radicals and CH radicals is collected simultaneously by an ICMOS camera 12 equipped with a bandpass filter, wherein the information of acetone molecules and OH radicals is distinguished by spatial position, and the fluorescence information is demodulated by a multiple exposure frequency recognition algorithm.

[0040] The encoding and decoding principle of the information of the present invention is as follows: the grating is located on the laser transmission path, and when the laser passes through the grating, multi-slit diffraction will occur. The diffracted light passes through a converging lens to focus the diffracted light field to the near field, so that higher-order light such as 0th order, ±1st order, ±2nd order, etc. will be generated on the diffraction plane. If a filter is placed at the diffraction plane to filter out the 0th order diffraction light and retain the ±1st order light, double-beam interference will occur after the two lasers pass through the filter to form modulated fringes. It is planned to adopt laser "encoding" and multiple exposure frequency identification (FRAME) scheme to perform spatial intensity modulation (i.e. "encoding") of the two lasers. After being excited by the encoded laser, CH free radicals and OH free radicals / acetone molecules will respectively radiate fluorescent signals with the same encoding information as the excitation laser. The encoded fluorescent signals are captured by the same high frame rate enhanced ICMOS camera. Through the "decoding" process, the information of the three components can be extracted from the original PLIF image respectively.

[0041] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other forms of assembly without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0042] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A device for simultaneously visualizing a mixed combustion process, characterized in that: The invention comprises a combustion device (1), a timing control system, a PLIF system, two laser systems and two structured light modulation and shaping systems. The combustion device (1) is connected to a gas supply pipeline (1-1) and an air supply pipeline (1-2). An acetone generating device (1-3) is arranged on the gas supply pipeline (1-1). The two laser systems are respectively arranged on both sides of the combustion device (1) to emit two laser beams. The output ends of the two laser systems are respectively arranged with a first frequency doubling (4) and a second frequency doubling (5) so that the two laser beams are output as 310.690 nm laser and 283.553 nm laser. The two laser systems are composed of a solid laser (2) and a dye laser (3). The solid laser (2) is used to emit laser light, and the dye laser (3) changes the laser light into different colors for differentiation. The 310.690 nm laser light is used to excite CH free radicals, and the 283.553 nm laser light is used to simultaneously excite acetone molecules and OH free radicals. The two sets of structured light modulation and shaping systems are respectively arranged between the two laser systems and the combustion device (1). The structured light modulation and shaping systems are sequentially arranged with an aperture stop (7), a beam expander (8), a grating (9), a collimator (1 0) and a focusing lens (11), so that the two laser beams are modulated and shaped into sheet light and then co-focally arranged with the combustion field of the combustion device (1), wherein the gratings (9) of the two sets of structured light modulation and shaping systems select different numbers of engraved lines so that the two laser beams have different modulation periods, and OH free radicals / acetone molecules and CH free radicals are encoded at the same spatial position, and the CH free radicals and OH free radicals / acetone molecules will respectively radiate fluorescent signals with the same encoding information as the excitation laser after being excited by the encoded laser, wherein the acetone molecules and OH free radicals are distinguished by the different spatial positions, and the acetone molecules are closer to the combustion field. The PLIF system comprises an ICMOS camera (12) and a computer. The ICMOS camera (12) is equipped with a bandpass filter and is arranged corresponding to the combustion field of the combustion device (1). The ICMOS camera (12) simultaneously captures the fluorescence radiated by acetone molecules, CH free radicals and OH free radicals and generates the collected PLIF images through the computer. The timing control system comprises a trigger (14) and two digital signal generators (13). The trigger (14) controls the two digital signal generators (13) to realize synchronous signal control of the PLIF system and the two laser systems.

2. The device for simultaneously visualizing a mixed combustion process according to claim 1, characterized in that: Flow meters are respectively provided on the gas supply pipeline (1-1) and the air supply pipeline (1-2).

3. The device for simultaneously visualizing a mixed combustion process according to claim 1, characterized in that: Reflector groups (6) are respectively arranged at the output ends of the first frequency doubling (4) and the second frequency doubling (5) to introduce the 310.690 nm laser and the 283.553 nm laser into the corresponding structured light modulation shaping system.

4. A method for simultaneous visualization detection of a mixed combustion process, characterized in that: According to the simultaneous visualization device of claim 1, the detection method thereof comprises the following steps: Step 1: Construction and debugging of laser system Two sets of laser systems are built and debugged on both sides of the combustion device (1), one of the laser systems outputs 310.690nm laser through the first frequency doubling (4) to excite CH free radicals, and the other laser system outputs 283.553nm laser through the second frequency doubling (5) to simultaneously excite acetone molecules and OH free radicals; Step 2: Construction of structured light modulation shaping system and information encoding Two sets of structured light modulation and shaping systems are built between the two sets of laser systems and the combustion device (1), so that the 310.690 nm laser and the 283.553 nm laser pass through the two sets of structured light modulation and shaping systems respectively, and after being modulated and shaped into sheet light, they are incident on the same position of the combustion field of the combustion device (1), thereby encoding OH free radicals / acetone molecules and CH free radicals at the same spatial position; Step 3: Construction of acetone generator and combustion device Connecting the gas supply pipeline (1-1) to the acetone generator (1-3), connecting the acetone generator (1-3) and the air supply pipeline (1-2) to the combustion device (1), and organizing the combustion of the gas in the combustion device (1); Step 4: Construction of timing control system Controlling two digital signal generators (13) via a trigger (14) enables synchronous signal control of the two laser systems and the PLIF system; Step 5: Build the PLIF system and decode the information The fluorescence information emitted by acetone molecules, OH free radicals and CH free radicals is collected simultaneously by an ICMOS camera (12) equipped with a bandpass filter, wherein the information of acetone molecules and OH free radicals is distinguished based on spatial positions, and the fluorescence information is demodulated by a multiple exposure frequency recognition algorithm.

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