Heat Release Effects on Shear-Layer Growth and Entrainment

Abstract

The effects of heat release were studied in a planar, gaseous reacting mixing layer formed between two subsonic freestreams; one containing hydrogen in an inert diluent, the other containing fluorine in an inert diluent. Sufficiently high concentrations of hydrogen and fluorine reactants were employed to produce adiabatic flame temperature rises of up to 940 K (adiabatic flame temperature of 1240 K absolute). Although the displacement thickness of the layer for a zero streamwise pressure gradient showed an increase with increasing heat release. the actual thickness of the mixing layer at a given downstream location was not observed to increase and, in fact, was characterized by a slight thinning. The overall entrainment into the layer was seen to be substantially reduced by heat release. The large-wale vortical nature of the flow appeared to persist over all levels of heat release in this investigation. Imposition of a favorable pressure gradient, though resulting in additional thinning of the layer was observed to have no resolvable effect on the amount of chemical product formation and hence on the mixing.

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