TEMPERATURE IMAGING IN A SUPERSONIC FREE JET OF COMBUSTION GASES WITH2-LINE OH FLUORESCENCE

Temperature measurements were performed in a shock-tunnel-generated fr ee jet of hydrogen/oxygen reaction products diluted in argon with a no nsimultaneous, two-excitation-line planar laser-induced fluorescence t echnique with the hydroxyl radical (OH) as a tracer. Single-shot image s were obtained with broadband excitation of isolated transitions in t he A (2) Sigma(+) <-- X (II)-I-2(1, 0) band of OH near 282 nm, with br oadband, temporally integrated detection of the resulting nonresonant emission. A measurement of the fluorescence lifetime in the free jet s howed no variation with excited rotational level, allowing the rotatio nal temperature to be obtained from the ratio of single-shot images wi th laser excitation of different rovibronic transitions.