Planar laser-induced fluorescence of OH in a chemically reacting boundary layer

Planar laser-induced fluorescence of hydroxyl radicals has been performed in a reacting boundary layer with emphasis on resolving the complications of performing these measurements in the vicinity of a wall. Excitation of the (1, 0) band of the A(2)Sigma-X(2)II transition at 282 nm coupled with detection of the fluorescence from the (1, 1) and (0, 0) bands near 310-nm minimized interference due to scattered light from the flow apparatus. A silicon intensified target detector provided 2-D images of hydroxyl radical concentration in the reacting boundary layer enabling visualization of ignition. Results are shown for the ignition of ethane-air mixtures over heated quartz or platinum surfaces highlighting the utility of the technique.