PARALLEL-BEAM TOMOGRAPHY BASED ON TDLAS

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 (tunable diode laser absorption tomography) has been developed 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, 7185.6cm ^-1and 7444.3cm ^-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 verification?experiment was performed using a premixed CH ₄/Air flat 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.