LIF imaging and 2D temperature mapping in a model combustor at elevated pressure

Abstract

Planar laser-induced fluorescence (PLIF) has been used to measure time-resolved spatial distributions of the fuel, the OH radical, and the temperature field in a jet engine model combustor segment. For temperature measurements, a two-line PLIF scheme was used: two different spectral lines of the OH radical, which served as indicator molecule, were excited successively within a short time delay using nanosecond pulses from two UV laser systems operating on different wavelengths. The ratio of the two fluorescence signals depends on the temperature; this forms the basis of the temperature measurement. To our knowledge, this temperature mapping technique has been applied for the first time in the high pressure combustion of kerosene. The fluorescence signal resulting from excitation by one of the two lasers is proportional to the OH density and provides thus information on the OH radical distribution and on flame structure. The same technique can be utilized to excite fluorescence from the fuel, thus providing qualitative information on kerosene distributions. These measurements yield information on flame structure, heat release and mixing properties, which can serve as design aids, as well as for CFD code validation purposes.