Development of a TDLAS sensor for temperature and concentration of H$_{2}$O in high speed and high temperature flows

The development of a sensor for simultaneous temperature concentration of H$_{2}$O and temperature in high speed flows is presented. H$_{2}$O is a desirable target sensing species because it is a primary product in combustion systems; both temperature and concentration profiles can be used to assess both the extent of the combustion and the flow field characteristics. Accurate measurements are therefore highly desirable. The sensor uses a vertical-cavity surface emitting laser (VCSEL) scanned at 50 kHz from 7172 to 7186 cm$^{-1}$. Temperatures and concentrations are extracted from the spectra by fitting theoretical spectra to the experimental data. The theoretical spectra are generated using GENSPECT in conjunction with line parameters from the HITRAN 2012 database. To validate the theoretical spectra, experimental spectra of H$_{2}$O were obtained at known temperatures (290-550 K) and pressures (~ 30 torr) in a heated static gas cell. The results show that some theoretical lines deviate from the experimental lines. New line-strengths are calculated assuming that the line assignments and broadening parameters in HITRAN are correct. This data is essential for accurate H$_{2}$O concentration and temperature measurements at low pressure and high temperature conditions.