Computational Investigation of Shock-Enhanced Mixing and Combustion

Abstract

A computational investigation of shock-enhanced mixing and combustion is presented. To understand the influences of the mixing process on the combustion process, the mixing characteristics of the reacting case are compared with those of the nonreacting case. Parametric studies varying the conditions of fuel injection are conducted to find the trends of the mixing and combustion processes. Three-dimensional Navier-Stokes equations with a chemical reaction model and κ-ω turbulence model are used. The upwind method of Roe's flux difference splitting scheme is adopted. It is shown that the mixing process has a strong influence on the combustion process, whereas the combustion process does not have any significant effect on the mixing process. The combustion process is divided into two mixing regimes: a convection-dominated regime, where the burning rate increases with distance from the injection plane, and a diffusion-dominated regime as one moves downstream, where burning rate is constant. In the parametric studies, varying the fuel pressure with the fuel density held fixed makes little difference, whereas varying the fuel density makes a significant difference in mixing rate and burning rate. A prediction of minimum combustor length for complete combustion is made.