Studies of diamond-shaped injectors in a supersonic flow
In this paper, we survey our results for sonic gaseous injection through diamond port injectors into supersonic freestreams. The overarching objective is to tailor the secondary flow structure to produced gasdynamic flame holding and provide enhanced stirring mechanisms. A brief review of our foundational Mach 5.0 numerical simulation is presented. This is followed by a description of our most recent reacting and nonreacting studies at Mach 2.0. The goals of the inert mixing studies were to (1) compare the flow structure around a diamond injector between two leading-edge injection angles (45 and 90 degrees) and (2) investigate the flow features with dual-port torch injection. The goal of the reacting studies, on the other hand, was to examine the reactivity in the lateral counter-rotating vortex pair (LCVP) under the high temperature test conditions. NO- and OH- planar laser-induced fluorescence (PLIF) diagnostics were used to accomplish these goals, and complementary 1-D and 3-D numerical simulations were performed. The plume penetration of the diamond port with 90-deg. leading-edge injection was found to be slightly higher than that with 45-deg. leading-edge injection. Furthermore, the NO-PLIF images captured the 3-D structure of the LCVP for the first time. OH consumption in the LCVP was clearly observed when ethylene was injected from the diamond port and the fuel-lean upstream torch was applied, but significant combustion and heat release were not attained. Unfortunately, we were unable to achieve, due to facility limitations, the necessary temperatures and pressures for flame holding. 2010 by the American Institute of Aeronautics and Astronautics, Inc.