PHOTOCHEMICAL IGNITION AND ENHANCEMENT OF SUPERSONIC COMBUSTION

SUCCESSFUL OPERATION OF FUTURE AEROSPACE VEHICLES (E.G. AOTV AND NASP) DEPENDS ON MAJOR ADVANCES IN COMBUSTIONTECHNOLOGY. THE CONDITION OF HIGH FLIGHT-SPEED IMPOSES SEVERE STRAINS ON IGNITION RELIABILITY AND OVERALL COMBUSTION EFFICIENCY. A NOVEL APPROACH TO ALLEVIATE THESE DIFFICULTIES IS PROPOSED. THE INNOVATIVE IDEA IS TO SELECTIVELY IRRADIATE REACTANTS, INTERMEDIATES, INHIBITORS OR SENSITIZERS IN THE COMBUSTION ZONE. THE ENSUING PHOTODISSOCIATION REACTIONS GENERATE HIGHLY REACTIVE RADICALS WHICH MODIFY THE GAS PHASE KINETICS AND LEAD TO IGNITION AND ENHANCEMENT VIA CHAIN-BRANCHING PATHS. THE OVERALL OBJECTIVE OF THIS PROPOSAL IS TO DETERMINE THE FEASIBILITY OF USING PHOTOCHEMICAL MEANS TO IMPROVE COMBUSTION PERFORMANCE UNDER SUPERSONIC FLOW CONDITIONS. SPECIFIC TASKS FOR PHASE I EFFORT ARE LIMITED TO IGNITION AND WILL INCLUDE: SUPERSONIC PURE PHOTOCHEMICAL IGNITION TESTS (IN CLOSE COOPERATION WITH NASA LANGLEY HYPERSONIC FACILITY); LITERATURE SEARCH TO IDENTIFY MOST SUITABLE PHOTO-SENSITIZERS; LABORATORY SCREENING TO QUANTIFYTHEIR EFFECTIVENESS; AND SUPERSONIC TESTS TO PROVE FEASIBILITY OF THE MOST LIKELY CANDIDATES FOR PHOTOCHEMICAL IGNITION. ANTICIPATED BENEFITS FOR RAMJET/SCRAMJET COMBUSTION ARE: 1) NON-INTRUSIVE AND RELIABLE IGNITION AND FLAMEHOLDING, WHICH WILL CIRCUMVENT ENGINE-DEGRADING SHOCK WAVES PRODUCED BY CONVENTIONAL DEVICES, AND 2) IMPROVEMENT IN OVERALL COMBUSTION EFFICIENCY WHICH WILL RESULT IN MAJOR SAVINGS IN WEIGHT, BULK AND COST.