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A computational assessment of independent stage control of a cascade injector was performed. This investigation used computational fluid dynamics to gain understanding of the mechanics governing the penetration characteristics of the cascade injector. Comparison to experimental data, the effects of the first injection stage, and a turbulence model study are presented. The computational solutions predicted penetration height with good accuracy compared to the experimental data, based on planar laser-induced fluorescence of the NO molecule, but were not as successful predicting injectant plume width. Penetration in the near-field was found to correspond with the position of the shock wave generated by the injectant. The Menter turbulence model produced higher values of eddy viscosity in the vicinity of the plume and more spreading, which agreed better with the experimental data. The computational data was also used to generate a synthetic laser-induced fluorescence signal, which was used to improve the penetration boundary prediction., Prepared in collaboration with the Aerospace Propulsion Division, Air Force Research Laboratory, Wright Patterson AFB, OH. Presented at the AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit (42nd) held in Sacramento, CA on 9-12 Jul 2006 and published in the proceedings of the same as paper AIAA 2006-4863. The original document contains color images. All DTIC reproductions will be in black and white.

An experimental investigation of a cascade injector was completed. The objective of this investigation was to determine whether the number of active stages in the cascade injector could be used to control penetration and mixing characteristics. The injector was tested at two overexpanded injection conditions in a Mach 3 crossflow. Shadowgraph and schlieren imaging, Mie scattering, Planar Laser Induced Fluorescence, and pressure profiling were the diagnostic techniques used to reveal various features of the injectant plume and its interaction with the supersonic crossflow. Results suggest that penetration can be controlled by the number of active stages in the cascade injector. Additional analysis and experiments are planned to better quantify the effects of injector stages revealed in this initial work., Prepared in cooperation with Innovative Scientific Solutions, Inc., Dayton, OH and AFRL/PRAS, Wright-Petterson, OH.