가변파장 레이저흡수분광법과 레이저유도플라즈마 분광법 복합을 통한 온도장 재건

Abstract

A new technique that reconstructs the temperature and species-concentration fields by using tunable diode laser absorption spectroscopy (TDLAS) and laser-induced breakdown spectroscopy (LIBS) is demonstrated on axisymmetric combustion fields. For two-line thermometry, the uncertainties in linestrengths of the absorption lines cause systematic errors in both temperature and species concentration estimations. Thus, in the study, the radial profile of water vapor concentration is obtained first using LIBS, assuming that the combustion is complete; then, the radial temperature profile is estimated from the radial profile of the absorption coefficient, as reconstructed from the absorbance profile obtained using TDLAS. The spectral line of water vapor at 7185.6 cm-1 is selected because its linestrength showed a monotonic decrease with the increase in temperature within the measuring temperature range. The radial profiles of temperature and water mole fraction are well-reconstructed, and the measurement error is found to be as low as 3%.