Passive mixing control via lobed injectors in high-speed flow.

摘要

High speed, non-reacting flowfields associated with lobed fuel injectors were studied both experimentally and numerically in order to understand the mixing processes associated with these devices. The experimental study involved using the non-intrusive technique of Planar Laser Induced Fluorescence (PLIF) of the injectant (N₂ seeded with acetone) while the numerical simulations involved a 2 − D time marching algorithm using vortex element methods.; For the experimental investigation, a Flight Test Fixture housing the components of the experiment was designed and fabricated. This fixture was inserted into a large scale “trisonic” wind tunnel in order to achieve high subsonic through transonic airflow speeds. PLIF imaging of the injectant in the nearfield was performed in order to study the evolution of the flowfield. From these images, various mixing and strain field parameters were quantified. It was found that the lobed geometries aided in mixing the injectant with the surrounding air in a much more rapid manner when compared to a non-lobed (i.e., straight slot) injector, while also providing an increase in the average strain rates.; Numerical simulations of the lobed injector flowfields were performed to corroborate and further explore these flows. These simulations compared the differences between an infinite width injector, a finite width injector, and a finite width injector which took into account the fabrication method by which the injector was constructed. Differences between the simulations of these different injector flowfields were seen in both the nearfield and farfield flow evolution. The nearfield flow evolution predicted by the simulations which account for the injector fabrication procedure agreed well with what was observed experimentally.