FLAME DIAGNOSTICS BY LIGHT SHEET IMAGING AND BY SHEARING INTERFEROMETRY

Combustion in a propane/air burner is analyzed by means of imaging mol ecular constituents present in the plane of a laser light sheet and by recording the local refractive index distribution, with a shearing: i nterferometer. The pulsed illumination with a UV light sheet yields an instantaneous image of the distribution of propane by elastic scatter ing, and of OH and CH radicals by laser-induced fluorescence. Spectral separation allows simultaneous and separate imaging of elastic and in elastic scattering, thus providing a means to analyze the spatial inte r-relation of propane, CH, and OH. In a fuel-rich flame, laser-induced incandescence of soot particles is observed. Calibration of propane c oncentration levels is achieved by the refractive index measurements, which also help to estimate flame temperatures.