Numerical investigation of the turbulent mixing performance of a cantilevered ramp injector

An injector geometry is considered for fuel delivery in a high-enthalpy, high-Mach-number airflow typical of that found in hypersonic propulsion systems such as the scramjet and shock-induced combustion ramjet or shcramjet. It is thought to embody the characteristics of both conventional ramp and low-angle wall injection techniques. The objective is to investigate the turbulent hypervelocity fuel/air mixing characteristics of the considered injector geometry, with particular emphasis on the effect of the convective Mach number and global equivalence ratio on its mixing efficiency. The analysis of the three-dimensional hypervelocity mixing flow is based on the Favre-averaged Navier-Stokes equations closed by the Wilcox kω turbulence model for a multispecies gas. A Roe scheme turned second-order accurate through a symmetric total-variation-diminishing limiter is used for the spatial discretization while approximate factorization is used to iterate in pseudotime. Obtained results show that the mixing efficiency varies by 31% for a convective Mach number ranging from 0 to 1.5 while the associated mass averaged stagnation pressure varies by only 10%. The mixing efficiency is shown to be increased by 30% for a threefold increase in the global equivalence ratio.