基于吸收光谱层析成像的气体摩尔分数和温度分布二维重建

Gas concentration and temperature distribution reconstruction based on absorption spectrum tomography technology

基于可调谐二极管激光吸收光谱层析成像技术,采用代数迭代重建算法,实现对气体摩尔分数场和温度场二维分布的重建.利用半透半反镜,将激光束反复穿过被测区域,用多个探测器依序接收,固定光路瞬时测量.建立H2O蒸气摩尔分数和温度分布模型,数值分析了初始光线角度、光线数目、网格数目对重建结果的影响.通过对初始假定分布数据进行取样得到期望数据,将期望数据与重建数据的对比结果作为重建结果评价依据,通过插值与初始数据比较评判整个重建方案.结果表明新的光线分布能够较好地对被测区域进行重建,同时证明了期望数据描述方法可行.

Based on tunable diode laser absorption tomography, two-dimensional distribution re- construction of gas concentration and temperature was realized using algebraic iterative reconstruction technique （ART）. Beam splitting lenses were used to make one laser beam cross the measurement area repeatedly. Thus could raise the utilization ratio of laser beam and simplify the structure of meas- urement platform. A model for H2O vapor concentration and temperature distribution was assumed, and numerical simulation was utilized using two absorption transitions. The influences of initial beam angle, the number of beams and grids on the reconstructed results were analyzed numerically. A con- cept of phantom description method used in simulation experiments was proposed in order to get closer to the real experiments. The method was used in the numerical simulation to evaluating concentration and temperature field reconstruction. Through data, and reconstructed result was obtained by this method, expected data were sampled from initial interpolation. The influence of random errors in projections on distribution reconstruction was also analyzed. The measurement plan could reconstruct the gas concentration and temperature distribution with a simplified platform using beam splitting lenses. The feasibility of the phantom description method was also proved bv the simulation experiment.