Numerical investigation of turbulent hydrogen combustion in a SCRAMJET using flamelet modeling

Abstract

A numerical method is presented for the simulation of turbulent diffusion flames in complex compressible flow fields. The method uses a two equation k - ϵ turbulence model combined with a stretched laminar flamelet model for turbulent diffusion flames as a mathematical description of the flame. Coupling between turbulence and non-equilibrium chemistry is achieved via a statistical description of the mixture fraction with a presumed β -probability density function (PDF) and a mean turbulent strain rate acting on the flame. The governing equations are solved by means of a fully implicit finite volume scheme on unstructured triangulated grids using an approximate Riemann solver for the convective fluxes and a central scheme for the viscous fluxes. The scheme is applied for the simulation of the hydrogen injection in a supersonic combustion ramjet engine (SCRAMJET) and the numerical results are compared qualitatively and quantitatively with shadow-pictures, velocity measurements, and temperature measurements in the case without, as well as with, combustion.