基于激光吸收光谱技术的燃烧场气体温度和浓度二维分布重建研究

Two-dimensional reconstructions of gas temperature and concentration in combustion based on tunable diode laser absorption spectroscopy

基于可调谐半导体激光吸收光谱技术和代数迭代算法(ART)实现燃烧场温度和浓度二维分布重建.采用时分复用技术,在1kHz扫描频率下分别扫描H2O的两条吸收谱线,7205.25和7416.05cm1,对温度分布在300—1100K范围内的气体温度场进行了重建.研究了投影角度和投影光线数目对温度场和浓度场重建结果的影响,并将温度场重建结果与热电偶测量结果进行比较,结果表明,采用四个投影方向时,温度场重建结果与热电偶测量结果除中心低温区域外基本符合.当光线数目减少时,通过在两条光线间增加虚拟光线,代入到迭代算法中,增加光线数目,提高了温度场和浓度场的重建效果.但此方法受到燃烧场温度梯度大小的影响,即在两条光线之间气体温度梯度较大,增加虚拟光线提高温度场重建效果不明显.

Based on the tunable diode laser absorption spectroscopy, the combustion gas concentration and temperature distribution are reconstructed using algebraic iterative reconstruction technique （ART）. Time division multiplexing technology is adopted to scan two H20 absorption transitions （7205.25 cm-1 and 7416.05 cm-1） simultaneously at 1 kHz repetition rate. The influences of projected angle and the number of beams on the temperature and concentration field reconstruction are studied. Compared with the thermocouple readings, the temperature distribution reconstruction has a well agreement except a low temperature area in the middle of the combustion field. Aiming to achieve an optimal reconstruction with a limited number of beams, a few virtual beams are added to the ART method. Through this method, the effectivenesses of temperature and concentration field reconstructions increase, but there is not an obvious improvement when a large gradient of temperature exists between two lines.