INNOVATIVE SCRAMJET FLAMEHOLDERS FOR ENHANCED MIXING

AN EXPERIMENTAL INVESTIGATION OF INNOVATIVE FLAMEHOLDER DESIGNS TO ENHANCE MIXING IN A SUPERSONIC COMBUSTION RAMJET (SCRAMJET) ENGINE IS PROPOSED. IN A SCRAMJET ENGINE OPERATING AT HYPERSONIC FLIGHT SPEEDS,THE SHORTER RESIDENCE TIME AND DECREASED MIXING RATE CAUSE DETERIORATION IN THE COMBUSTION EFFICIENCY AS COMPARED WITH LOWER SPEEDS. TWO CONFIGURATIONS RECENTLY DEVELOPED TO PROMOTE RAPID MIXING FOR SUBSONIC FLOWS WILL BE TESTED IN A SUPERSONIC FLOW AND EXPERIMENTALLY COMPARED WITH A BASELINE CONVENTIONAL CONFIGURATION. THE TWO CONFIGU-RATIONS ARE A MULTIPLE-STEP FLAMEHOLDER AND A THREE-DIMENSIONAL "TOOTHED" STEP FLAMEHOLDER. THE OBJECTIVE OF THIS STUDY IS TO EVALUATE THE CONFIGURATIONS, OR COMBINATIONS OF THEM, AS A MEANS OF RAPID AND THOROUGH MIXING OF THE FUEL WITH THE SUPERSONIC AIR STREAM. DURING PHASE I, THE FEASIBILITY OF THESE SCRAMJET MIXING CONCEPTS WILLBE DETERMINED. PHASE I WILL INVOLVE AN EXPERIMENTAL STUDY OF THE CONFIGURATIONS USING A FACILITY SIMILAR TO A BLOW-DOWN WIND TUNNEL. WE PLAN TO MIX HELIUM WITH NITROGEN AND MEASURE THE CONCENTRATION PROFILE AT A SUITABLE DISTANCE DOWNSTREAM OF THE STEP. IT IS EXPECTED THAT THE NEW MIXING CONFIGURATIONS WILL ALLOW THE HELIUM TO DIFFUSE MORE RAPIDLY ACROSS THE SUPERSONIC NITROGEN FLOW. WITH FAVORABLE RESULTS IN PHASE I, A PHASE II RESEARCH AND DEVELOPMENT PRO-GRAM WILL BE PURSUED TO PROVIDE PARAMETRIC INFORMATION FOR DESIGN OPTIMIZATION.