基于TDLAS技术的燃烧火焰场分布二维重建研究
发布时间：2019-06-19 15:45
【摘要】：燃烧火焰的温度及其组分浓度是燃烧过程中非常重要的两个参数,表征了污染物排放的多少,燃烧效率的高低,发动机性能的优劣等。因此,发展适用于高温燃烧环境的先进气体检测技术已成为近些年来众多学者研究的热点。可调谐半导体激光吸收光谱技术(Tunable Diode Laser Absorption Spectroscopy,TDLAS)作为一种非侵入式、响应速度快、抗干扰能力强的光谱检测技术,已经在燃烧流场诊断中发挥了重要的应用,它可以实现组分浓度、温度、压力和流速等多参数的在线精确测量。由于受到热传递、气流波动、燃料分布不均、边界层效应等因素的影响,燃烧流场通常具有一定的非均匀性。本文深入地研究了 TDLAS技术在燃烧火焰温度和组分浓度测量方面的应用,同时研究了计算机层析成像算法(Computed tomography,CT),实现了平焰炉表面燃烧场的二维重建。首先基于HITRAN2012数据库选择了 H20的7154.35 cm 1和7467.77 cm 1这两条测温谱线,在实验室搭建了高温炉实验系统,进行了选线验证和温度测量方法研究,同时对McKenna平焰炉燃烧当量比为1的火焰进行了温度浓度连续测量,验证了吸收光谱法测温的可行性。然后系统地研究了两种典型的重建算法—滤波反投影算法(FBP)和代数迭代算法(ART)。对于FBP算法,模拟研究了少光束投影下的场分布重建,提出了吸收系数的归一化处理方法,获取了准确的浓度分布图像,研究了平行射束扫描时,单视角下光线数目、投影角度个数和投影数据噪声对重建精度的影响,提出针对圆对称场的FBP重建方法。对于ART算法,在传统方法的基础上,本文提出采用自适应松弛因子、加入平滑准则、考虑非负限定三个措施来改善重建效果。研究了一种求解ART投影系数的递推算法,实现了任意网格划分下投影系数的快速精确计算。改进了浓度重建的传统方法,提出一种二次迭代直接重建浓度法,获得了更加精确的H20浓度重建结果。同时研究了不同的投影光线总数和正交光束布局对温度重建精度的影响,为实际实验中投影光线布局提供了理论参考。最后在实验室已有直径为60mm的McKenna平焰炉上,搭建了一套燃烧流场二维重建系统,设计了一种光束插空布局的光机结构,解决了有限重建区域下的多光束扫描难题。利用Labview编写了数据采集与处理软件,实时在线获取了投影数据,并多次测量取平均值,有效地消除了偶然误差。基于FBP算法实现了圆对称燃烧场分布测量,解决了完备投影数据获取难题。基于改进ART算法进行了正交光束布局的场分布测量,实现了高分辨率11×11的二维温度浓度重建。将旋转台和平移台结合起来使用,通过单光路扫描加旋转的方式在正交方向布置了更多的光束,获得了 15×15的更高分辨率重建,在此基础上,加入10条倾斜光束作重建限定约束,可以使重建图像趋于炉面几何形状的真实结构。将实验中重建出来的炉面中心区域13个燃烧较为稳定的温度像素值与热电偶点测结果进行对比分析,结果发现二者的最大偏差是6.8%,平均偏差为4.0%,验证了二维重建算法的可行性。本论文通过吸收光谱选线、重建算法研究、数值模拟分析、实验测量验证,发展了基于TDLAS技术的燃烧流场温度和组分浓度的二维分布重建,实现了燃烧火焰非均匀流场的高分辨高精度测量,对于推动TDLAS技术在燃烧流场诊断中的应用研究具有重要的理论指导意义和工程实验价值。
[Abstract]:The temperature and its component concentration of the combustion flame are two parameters which are very important in the combustion process, which are characterized by the quantity of the pollutant discharge, the high and low of the combustion efficiency, the good and the good of the performance of the engine, etc. Therefore, the development of advanced gas detection technology suitable for high-temperature combustion environment has become a hot point for many scholars in recent years. The tunable semiconductor laser absorption spectroscopy (TDLAS), as a non-invasive, fast and anti-interference spectrum detection technology, has played an important role in the diagnosis of combustion flow field, which can realize the component concentration and temperature, And the on-line accurate measurement of the multi-parameter such as pressure and flow rate. The combustion flow field usually has certain non-uniformity due to the influence of heat transfer, gas flow fluctuation, uneven fuel distribution, boundary layer effect, and the like. In this paper, the application of TDLAS in the measurement of combustion flame temperature and component concentration is studied in depth, and the computer tomography (CT) is also studied to realize the two-dimensional reconstruction of the combustion field on the surface of the flat-flame furnace. Based on the HITRAN2012 database, the two temperature measurement lines of 7154.35cm 1 and 7467.77 cm 1 of H20 are selected. The experimental system of high-temperature furnace is set up in the laboratory, and the method of line selection verification and temperature measurement is carried out, and the temperature concentration of the flame of the McKena flat-flame furnace is continuously measured. The feasibility of the temperature measurement of the absorption spectrum method is verified. Two typical reconstruction algorithms (FBP) and algebraic iterative algorithm (ART) are then systematically studied. For the FBP algorithm, the field distribution reconstruction under the low beam projection is simulated, the normalized processing method of the absorption coefficient is proposed, the accurate concentration distribution image is obtained, the number of light rays in a single visual angle is studied when the parallel beam is scanned, The influence of projection angle number and projection data noise on the reconstruction precision is proposed, and the FBP reconstruction method for circular symmetric field is proposed. For ART algorithm, on the basis of the traditional method, this paper proposes to adopt the self-adaptive relaxation factor, join the smoothing criterion, and consider the non-negative limiting three measures to improve the reconstruction effect. In this paper, a recursive algorithm for solving the ART projection coefficient is studied, and the rapid and accurate calculation of the projection coefficient under arbitrary grid division is realized. The traditional method of concentration reconstruction is improved, and a direct reconstruction concentration method for the secondary iteration is proposed, and a more accurate reconstruction result of the H20 concentration is obtained. At the same time, the influence of the total number of different projection light and the layout of the orthogonal beam on the accuracy of the temperature reconstruction is studied, and the theoretical reference is provided for the projection light layout in the practical experiment. At last, a set of two-dimensional reconstruction system of combustion flow field is set up in the laboratory of McKena flat-flame furnace with a diameter of 60 mm, and an optical machine structure of light beam insertion and air layout is designed to solve the problem of multi-beam scanning under the limited reconstruction area. The data acquisition and processing software is developed by Labview. The projection data is acquired on-line in real time, and the average value is measured on a number of times, and the accidental error is effectively eliminated. The circular symmetric combustion field distribution measurement is realized based on the FBP algorithm, and the problem of complete projection data acquisition is solved. The field distribution measurement of the orthogonal beam layout is carried out based on the modified ART algorithm, and the two-dimensional temperature concentration reconstruction of the high-resolution 11-stage 11 is realized. the rotating platform and the translation table are combined to be used, more light beams are arranged in the orthogonal direction by a single light path scanning and adding rotation mode, a higher resolution reconstruction of 15 to 15 is obtained, The reconstructed image can be made to tend to have a true structure of the furnace surface geometry. The results show that the maximum deviation is 6.8%, the average deviation is 4.0%, and the feasibility of the two-dimensional reconstruction algorithm is verified. The two-dimensional distribution reconstruction of the temperature and component concentration of the combustion flow field based on the TDLAS technique is developed by means of absorption spectrum line selection, reconstruction algorithm research, numerical simulation analysis and experimental measurement. The high-resolution and high-precision measurement of the non-uniform flow field of the combustion flame is realized. It is of great significance to study the application of TDLAS in the diagnosis of combustion flow field.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O643.21
本文编号：2502451
[Abstract]:The temperature and its component concentration of the combustion flame are two parameters which are very important in the combustion process, which are characterized by the quantity of the pollutant discharge, the high and low of the combustion efficiency, the good and the good of the performance of the engine, etc. Therefore, the development of advanced gas detection technology suitable for high-temperature combustion environment has become a hot point for many scholars in recent years. The tunable semiconductor laser absorption spectroscopy (TDLAS), as a non-invasive, fast and anti-interference spectrum detection technology, has played an important role in the diagnosis of combustion flow field, which can realize the component concentration and temperature, And the on-line accurate measurement of the multi-parameter such as pressure and flow rate. The combustion flow field usually has certain non-uniformity due to the influence of heat transfer, gas flow fluctuation, uneven fuel distribution, boundary layer effect, and the like. In this paper, the application of TDLAS in the measurement of combustion flame temperature and component concentration is studied in depth, and the computer tomography (CT) is also studied to realize the two-dimensional reconstruction of the combustion field on the surface of the flat-flame furnace. Based on the HITRAN2012 database, the two temperature measurement lines of 7154.35cm 1 and 7467.77 cm 1 of H20 are selected. The experimental system of high-temperature furnace is set up in the laboratory, and the method of line selection verification and temperature measurement is carried out, and the temperature concentration of the flame of the McKena flat-flame furnace is continuously measured. The feasibility of the temperature measurement of the absorption spectrum method is verified. Two typical reconstruction algorithms (FBP) and algebraic iterative algorithm (ART) are then systematically studied. For the FBP algorithm, the field distribution reconstruction under the low beam projection is simulated, the normalized processing method of the absorption coefficient is proposed, the accurate concentration distribution image is obtained, the number of light rays in a single visual angle is studied when the parallel beam is scanned, The influence of projection angle number and projection data noise on the reconstruction precision is proposed, and the FBP reconstruction method for circular symmetric field is proposed. For ART algorithm, on the basis of the traditional method, this paper proposes to adopt the self-adaptive relaxation factor, join the smoothing criterion, and consider the non-negative limiting three measures to improve the reconstruction effect. In this paper, a recursive algorithm for solving the ART projection coefficient is studied, and the rapid and accurate calculation of the projection coefficient under arbitrary grid division is realized. The traditional method of concentration reconstruction is improved, and a direct reconstruction concentration method for the secondary iteration is proposed, and a more accurate reconstruction result of the H20 concentration is obtained. At the same time, the influence of the total number of different projection light and the layout of the orthogonal beam on the accuracy of the temperature reconstruction is studied, and the theoretical reference is provided for the projection light layout in the practical experiment. At last, a set of two-dimensional reconstruction system of combustion flow field is set up in the laboratory of McKena flat-flame furnace with a diameter of 60 mm, and an optical machine structure of light beam insertion and air layout is designed to solve the problem of multi-beam scanning under the limited reconstruction area. The data acquisition and processing software is developed by Labview. The projection data is acquired on-line in real time, and the average value is measured on a number of times, and the accidental error is effectively eliminated. The circular symmetric combustion field distribution measurement is realized based on the FBP algorithm, and the problem of complete projection data acquisition is solved. The field distribution measurement of the orthogonal beam layout is carried out based on the modified ART algorithm, and the two-dimensional temperature concentration reconstruction of the high-resolution 11-stage 11 is realized. the rotating platform and the translation table are combined to be used, more light beams are arranged in the orthogonal direction by a single light path scanning and adding rotation mode, a higher resolution reconstruction of 15 to 15 is obtained, The reconstructed image can be made to tend to have a true structure of the furnace surface geometry. The results show that the maximum deviation is 6.8%, the average deviation is 4.0%, and the feasibility of the two-dimensional reconstruction algorithm is verified. The two-dimensional distribution reconstruction of the temperature and component concentration of the combustion flow field based on the TDLAS technique is developed by means of absorption spectrum line selection, reconstruction algorithm research, numerical simulation analysis and experimental measurement. The high-resolution and high-precision measurement of the non-uniform flow field of the combustion flame is realized. It is of great significance to study the application of TDLAS in the diagnosis of combustion flow field.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O643.21
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