Comparison of the mixing efficiency of different injector configurations

•Mixing efficiency comparison of a plane injector and one with streamwise ramps.•Injection of a heavy precursor into an accelerated hot transonic nozzle flow.•Flow acceleration rapidly decreases turbulence.•No significant difference in spatial mixing homogeneity for both injectors.•Significantly improved temporal homogeneity for the ramp configuration.

The mixing efficiency of two injector configurations, one with a plane geometry and one with a streamwise-ramp geometry, is compared. The dense precursor gas tetraethoxysilane (TEOS – Si(C2H50)4Si(C2H50)4) is premixed with nitrogen and ejected through circular holes in the base of each injector into the nozzle flow at a co-flow Mach number of Maco-flow≈0.66Maco-flow≈0.66 and a temperature of Tco-flow≈1200K. Immediately downstream of the blunt trailing edge of the injector the flow field is accelerated to supersonic speed. The mixing process is determined by a multi-species large-eddy simulation (LES). The analysis shows a higher mixing efficiency of the streamwise ramp configuration against the plane geometry. Especially the temporal homogeneity is improved as a result of reduced vortex shedding at the injector base.