PLIF thermometry based on measurements of absolute concentrations of the OH radical

Abstract

A method for measurements of planar temperature distributions based on planar laser-induced fluorescence (PLIF) of the OH radiacal is described. The technique was developed specifically for the application in lean combustion systems, where OH equilibrium concentrations are largely independent on equivalence ratio and a function of temperature only. It is thus possible to derive a temperature information from measurements of absolute OH concentration, which can be obtained from a combined PLIF/absorption measurement. This paper discusses the basics of the method, and de-scribes validation experiments in high pressure laminar premixed flames which were performed to asses its appli-cability and accuracy. Therefore, we compared our LIF based results with CARS measurements performed in the same flames. Finally, an example for the application in a lean gas turbine model combustor is discussed.