Two component laser velocimeter measurements in a dump combustor flowfield

Two component, Bragg-diffracted laser velocimeter measurements were obtained on a ducted, turbulent, hydrogen-air flow field, both with and without chemical reactions. The geometric configuration was designed to be representative of a sudden expansion or 'dump' combustor. The air stream was seeded with one-micron alumina particles. Radial distributions of mean axial velocity, radial velocity, and turbulence intensity were obtained for axial stations from one-half to six duct diameters from the nozzle exit plane. A comparison of the laser velocimeter data obtained in the flow field with and without chemical reaction is presented to demonstrate the usefulness of LV measurements in determining the effect of the chemical reaction on the flow field mixing rate and the size and location of the recirculation zone within the mixing duct. Comparison of the laser velocimeter data with calculations assuming frozen or equilibrium chemistry are presented to demonstrate the self-consistency in the measured velocity, pressure and gas composition. Operational difficulties encountered in application of the laser velocimeter to a highly turbulent, chemically reacting flow field are discussed.