Mixing and chemical reaction at high Schmidt number near turbulent/nonturbulent interface in planar liquid jet

This study investigates the mixing of reactive species at a high Schmidt number (Sc approximate to 600) near the turbulent/nonturbulent (T/NT) interface in a planar liquid jet with a chemical reaction A + B -> R. Reactants A and B are supplied from the jet and ambient flows, respectively. An I-type hot-film probe and optical fiber probe are used for the simultaneous measurements of the streamwise velocity, mixture fraction, and concentrations of all reactive species and for detecting the T/NT interface. Statistics conditioned on the time elapsed after interface detection are analyzed. The conditional mean mixture fraction and concentrations change sharply near the interface. The widths of these changes are independent of the chemical species. The conditional statistics reveal the dependence of the chemical reaction on the interface orientation. The segregation intensity near the interface shows that the mixing state of the two reactants also depends on the interface orientation. However, the large reaction rate near the interface is related to the large concentration of reactant A rather than the mixing state, because reactant A supplied from the jet tends to be deficient near the interface. Near the interface where the reaction rate is large, the concentration of the chemical product is also large. The difference in the product concentration between the different interface orientations is larger for the infinitely fast reaction (as investigated by using the equilibrium limit) than the finite Damkhler number case, and the dependence of the chemical reaction on the interface orientation is expected to be significant for a fast chemical reaction. (C) 2015 AIP Publishing LLC.