TRANSVERSE GAS-JET INJECTION BEHIND A REARWARD-FACING STEP

An experimental and theoretical study of the behavior of a transverse gas Jet injected behind a rearward-facing step in supersonic now is de scribed. In-flight iodine planar laser-induced fluorescence imaging wa s performed to study this flowfield at NASA Dryden Flight Research Cen ter using a flight test fixture situated under the fuselage of an F-10 4G aircraft, Jet structure and penetration data were obtained, in addi tion to limited characteristics for jet mixing and for supersonic flow over a rearward-facing step in a flow regime and for injection locati ons not extensively studied in the past. A model for jet behavior is d escribed that places emphasis on the dynamics of the vortical structur es observed to dominate jet cross section, The complex flowfield forme d downstream of the step is represented by a combination of empirical and analytical correlations, Model predictions for jet trajectories co mpare reasonably well with results from the present in-flight experime nts as well as with prior wind-tunnel experimental data.