基于TDLAS的层析成像技术TDLAT

PARALLEL-BEAM TOMOGRAPHY BASED ON TDLAS

可调谐二极管吸收光谱技术(tunable diode laser absorption spectroscopy,TDLAS)已成为超声速燃烧的重要测量手段之一.为提高其空间分辨能力,需发展基于TDLAS,结合层析成像术的二维断层成像术(tunable diode laser absorption tomography,TDLAT).设计了一套基于6平行光束--旋转测量的新型TDLAT系统,吸收波长为7185.6cm-1和7444.3cm-1双线,采用分时--直接吸收探测策略.重建中,使用代数重建算法,先分别反演计算两吸收线的吸收率和吸收比分布,再获得温度和浓度分布.利用该系统,在CH4/Air预混平面燃烧炉上开展初步验证试验.结果表明,TDLAT系统可以反演出温度和浓度分布特征,反演的温度分布结果与热电偶测量值吻合较好.进一步改进该系统,可用于超燃直连台中,测量燃烧室出口气流的温度和组分浓度分布.

Tunable diode laser absorption spectroscopy （TDLAS） has been one of the most powerful techniques for combustion diagnostics in high speed flow. In order to improve its spatial solution, a new method called TDLAT （tun- able diode laser absorption tomography） has been deveioped combining with computed tomography （CT）. This study reports a TDLAT system composed of six parallel beams and a motorized？rotation？stage. Two water vapor absorption lines, 7 185.6cm-1 and 7444.3 cm-1, were utilized in each beam. Temperature and concentration distribution can be deduced after the reconstruction of absorbance of the line-pair using algebraic reconstruction technique （ART）. A veri- fication？experiment was performed using a premixed CH4/Air fiat burner. Comparing with thermocouple measurement, the good temperature reconstruction indicates that this TDLAT can capture the primary characteristic of this flame. More researches about TDLAT are undergoing. The future improved TDLAT system will be used to measure the temperature and concentration distributions in a scramjet facility.