Chemical energy release, spanwise excitation, and dynamics of transitional reactive free shear flows

Abstract

IVe report results from numerical studies of a compressible, subsonic reactive mixing layer. The focus of the research is to investigate the effects of chemicalreaction exothermicity and 3D spanwise excitation on the growth of the shear layer, and the dependence of these effects on initial conditions. The model solves the unsteady, conservation equations for mass, m* mentum, energy, and species-concentrations in three dimensions. The convective transport equations are solved using the Flux-Corrected Transport (FCT) algorithm, directionaland timestep-splitting techniques, and appropriate inflow and outflow houndary conditions. A fourth-order phaseaccurate FCT algorithm is used in the model. A one-step, irreversible, Arrhenious chemical reaction rate, and realistic (speciesand temperaturedependent) modeling of diffusive transport are coupled with the convective transport using timestep-splitting. The numerical studies show that energy release can have the effect of reducing the shear layer growth and the amount of chemical product formed, with the combustion becoming less efficient as the free-stream fuel molar-concentration is increased in the range studied (10%-40%). The,threedimensional (3D) simulations show that enhanced entrainment and chemical production can be obtained by introducing sinusoidal spanwise perturbation of the inflowing streams. d