基于TDLAS技术的燃烧场温度与气体浓度分布重建研究

发布时间：2018-08-06 20:09

【摘要】：可调谐二极管激光吸收光谱技术可实现对气体温度、浓度、流速及压强等参数的检测,该技术具有灵敏度高,响应速度快,系统简单,可实现非接触、无扰动的测量,在燃烧诊断领域具有很大的应用潜力。将该技术与CT技术相结合,可实现燃烧流场温度和组分浓度的二维分布检测。本论文基于可调谐二极管激光吸收光谱技术分别以燃烧相关的O_2和H_2O两种气体为目标测量气体,开展了对燃烧过程中温度和气体浓度检测的研究,同时通过数值模拟和实验进行了二维分布重建中算法和光束分布研究。主要开展的研究内容和创新点有:(1)利用氧气的两条吸收谱线,结合波长调制理论和温度反演算法,提出了基于波长调制技术对温度测量的标定方法。在实验室利用高温管式炉和两台激光器搭建了一套实时温度测量系统,该系统通过分时锯齿扫描技术,实现了用一套锁相设备分别对两条吸收谱线的谐波信号进行解调。设计了动态温度测量和稳态温度测量两组实验,分别验证了温度测量系统的响应速度,测量精度,以及标定算法的可行性。在300 K到900 K温度范围内,系统的测量误差在±20 K,其相对精度在±4%以内,并从实验系统和影响二次谐波信号的因素等方面详细分析了实验的误差来源。(2)针对不均匀燃烧场温度测量,提出了一种去除边界层低温段对测量结果影响的修正方法,以获得对燃烧场中心区域温度更高精度的测量;利用开发的Matlab测温谱线对的选择程序,在大量的H_20吸收谱线中选取了 1395.51 nm和1395.69 nm两条吸收谱线进行了非均匀一维温度和浓度测量实验,结果表明,燃烧场中心区域的温度测量精度由修正前的10%提高到3%以内,测量最大偏差小于30 K,并通过控制空气流量改变燃烧状态,对其温度和水气浓度的实时连续测量,验证了该多路径在线测量系统和修正算法的稳定性和可行性。(3)改进了二维分布重建算法,通过数值模拟对比了改进前后的重建效果,并在实验中验证了该算法的可行性。数值模拟研究了光束分布对重建结果空间分辨和准确度的影响,提出了光束需分布在与燃烧场对称轴垂直和平行方向上,才能得到有效利用的方法。同时,为减小安装的复杂性,设计了一种双对射光路结构,使得在有限的安装窗口数量下,得到更多的光束角度和数量,该光束分布方式对多数燃烧场都有较好的适用性。搭建了一套燃烧场温度和浓度二维分布同时在线重建实验系统,基于该试验系统重建了不同燃料空气当量比下温度和水气浓度分布变化,其燃烧场峰值温度与热电偶测量结果的相对误差小于5.6%,而水气浓度的反演结果与理论计算结果的相对误差在8.6%以内。另外,分别重建了由两个炉面构成的不同燃烧场温度和水气浓度二维分布情况,结果表明,当光束方向与燃烧场对称轴垂直和平行时可得到与实际燃烧场分布相一致的重建效果。
[Abstract]:Tunable diode laser absorption spectroscopy can detect the parameters of gas temperature, concentration, velocity and pressure. This technology has high sensitivity, fast response and simple system. It can realize non-contact and undisturbed measurement. It has great potential in the field of combustion diagnosis. This technology can be combined with CT technology to achieve combustion. Based on the tunable diode laser absorption spectroscopy (tunable diode laser absorption spectroscopy), the measurement of temperature and gas concentration in the combustion process was studied in this paper, based on the tunable diode laser absorption spectroscopy (tunable diode laser absorption spectroscopy), and the two dimensional distribution was carried out through numerical simulation and experiment. The main research contents and innovation points are as follows: (1) using two absorption spectra of oxygen, combining wavelength modulation theory and temperature inversion algorithm, a calibration method for temperature measurement based on wavelength modulation technology is proposed. In the laboratory, a set of high temperature tube furnace and two lasers have been used to build a set of real-time temperature. The system realizes the demodulation of the harmonic signals of two absorption lines by a set of phase-locked equipment through the time-sharing sawtooth scanning technology. The dynamic temperature measurement and steady temperature measurement are designed in two groups. The response speed of the temperature measurement system, the measurement accuracy, and the feasibility of the calibration algorithm are verified, respectively, in 3. In the range of temperature from 00 K to 900 K, the measurement error of the system is within + 20 K, its relative accuracy is within + 4%, and the error sources of the experiment are analyzed in detail from the experimental system and the factors affecting the two harmonic signals. (2) a correction of the effect of the removal of the low temperature of the boundary layer on the measurement results is proposed for the measurement of the temperature of the uneven combustion field. The method is to measure the temperature of the central region of the combustion field to be more accurate. Using the selected program of the developed Matlab spectrum line pair, 1395.51 nm and 1395.69 nm absorption lines are selected in a large number of H_20 absorption lines to measure the inhomogeneous temperature and concentration of one dimensional temperature and concentration. The results show that the temperature of the central region of the combustion field The measurement accuracy is increased from 10% before the correction to less than 3%, the maximum deviation is less than 30 K, and the stability and feasibility of the multi-path on-line measurement system and the correction algorithm are verified by controlling the air flow to change the combustion state and the real-time continuous measurement of its temperature and water gas concentration. (3) the two-dimensional distribution reconstruction algorithm is improved and the number is improved. The value simulation compares the reconstruction effect before and after the improvement, and verifies the feasibility of the algorithm in the experiment. The numerical simulation studies the effect of the beam distribution on the spatial resolution and accuracy of the reconstruction results. The method is proposed that the beam need to be effectively used in the vertical and parallel direction of the beam to the combustion field. With the complexity of the installation, a two pair beam structure is designed to obtain more angle and quantity of light beam under the limited number of installation windows. The beam distribution mode has good applicability to most of the combustion fields. A set of experimental system for simultaneous on-line reconstruction of the temperature and concentration of the combustion field is set up, based on the experimental system. The variation of temperature and gas concentration distribution under different fuel air equivalent ratio is rebuilt. The relative error of the peak temperature of the combustion field and the results of the thermocouple is less than 5.6%, and the relative error between the inversion results of the gas concentration and the theoretical calculation is less than 8.6%. In addition, the different combustion field temperatures made up of two furnace surfaces are rebuilt respectively. The results show that the reconstruction effect consistent with the actual combustion field distribution can be obtained when the beam direction is perpendicular to the symmetry axis of the combustion field and parallel to the combustion 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;O657.3

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