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.