Laser-induced-fluorescence visualization of transverse gaseous injection in a nonreacting supersonic combustor

Abstract

A laser-induced-fluorescence (LIF) visualization study is reported of transverse gaseous injection into a Mach 2.07 freestream. The purpose of the study was to obtain an experimental data base for validating calculations of three-dimensional mixing in supersonic combustor flowfields without chemical reaction. Three injection configurations were studied: 1) injection from a single orifice into a constant-area duct, 2) injection from a single orifice behind a rearward-facing step, and 3) injection from staged orifices behind a reaward-facing step. Densitometer scans of LIF photographic negatives allowed injectant penetration and spreading profiles to be quantitatively determined for each injection configuration over a range of injection dynamic pressure ratio. These data represent the first detailed measurements of the three-dimensional flowfield in the vicinity of the injectors. Shock-structure tirple points were located visually as a second measure of injectant penetration. Parametric functions were fit to the data to establish quantitatively the effect of a rearward step, staged injection, and injection dynamic pressure ratio on injectant penetration and spreading into a supersonic flow without chemical reaction.