Chemically Reacting, Turbulent Shear Layer

Abstract

A chemically reacting, turbulent shear layer between two streams was investigated in a new, blowdown water tunnel. The two streams contained dilute, aqueous solutions of diffusion-limited reactants (phenolphthalein and sodium hydroxide, respectively) which mixed in the layer and reacted to form a visible reaction product. Using optical densitometry techniques, the amount of product was measured as a function of Reynolds number. These results for water (Schmidt No. = 600) are compared with the previous mixing measurements of Konrad in a gaseous shear layer (Sc = 0.7) and the simple mixing method of Broadwell. The unique flow visualization provided by the visible reaction product revealed a remarkable spanwise instability (superimposed on the large coherent vortices) which appears to be important in introducing three-dimensional motions into the flow.

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