Laser absorption methods for simultaneous determination of temperature and species concentrations through a cross section of a radiating flow

An active laser absorption technique is proposed for simultaneous determination of temperature and species concentrations of a combustion flow. For homogeneous medium, the conventional method of ratio of the Boltzmann's population distribution factors to determine temperature is extended to include influence of the interfering species from measurements of multiple monochromatic absorptions. It is further shown that this technique may be used to retrieve two-dimensional thermodynamic variables across a selected cross section. The problem of solving a nonhomogeneous case is reduced to that of a homogeneous one if an appropriate multidirection scanning technique is employed.