Quantitative visualization of combustion species in a plane

Multiple-point measurements of species concentration and other flow properties in combustion gases are needed to guide the formulation of models describing interactions between the chemistry and fluid mechanics of combustion phenomena. A description is presented of a new technique for quantitative single-shot measurements of combustion species concentration in a plane. Results based on a laser-induced fluorescence are provided for OH in both a premixed laminar flat flame and a premixed turbulent flame. The technique yields submillimeter spatial and submicrosecond temporal resolution and permits spatial correlations to be viewed directly. The method is applicable to a variety of combustion species. A sheet of laser light, tuned to an optical resonance of the species being probed, is transmitted across the flow field under study. Part of the light is absorbed and reemitted as fluorescence. A fraction of the fluorescence radiation is focused on a camera. The output of the camera is displayed or processed.