Mixing and combustion augmentation of the RBCC with different mixer configurations in ejector mode

Abstract

Achieving mixing and combustion augmentation of air and rocket exhaust gases become a crucial issue in RBCC ejector mode, in which the mixer is an effective way to improve mixing efficiency. In current study, the three-dimensional coupled implicit Reynolds average Navier-Stokes (RANS) equations, SST k-ω turbulent model and Eddy-Dissipation Concept (EDC) reaction model are employed to investigate the flow fields with different mixer configurations, namely the lobe, rectangle, triangle, and pentagon. The simulated pressure of the prototype has the same trend with the experimental results. The different grid scales bring only a subtle difference for the simulation results, which prove the validity of the calculation results. Simultaneously, the vortex structure, mixing efficiency, combustion efficiency and total pressure loss are investigated. The results show that the lobed mixer and rectangle mixer retain the best mixing combustion augmentation characteristics, and the triangle is the worst. Besides, with the number of lobes decreases, the larger scale vortex structure is induced downstream the mixers. It improves the combustion performance by enhancing the penetration depth. Finally, all mixers only generate the total pressure loss downstream instead of the current location, revealing that mixers have less impact on the friction loss of the inflow.