Flameholding methods for compact hypersonic systems
Methods of flameholding enhancement for ethylene-fueled compact hypersonic systems were characterized using high-speed pressure measurements and imaging in the high-enthalpy supersonic facility ACT-II. “Hypermixer” geometries consisting of tapered wedges with and without expansion-ramp vortex generators were tested in an axisymmetric Mach 2.6 flowpath to assess their performance in combination with a cavity flameholder. It was observed that the hypermixer geometries enhanced fuel-air mixing and flameholding through turbulent flame production as well as an enhancement of cavity activity, and were suited for establishment of ram-mode combustion. Additionally, the presence of a cavity flameholder was necessary for autoignition at the tested conditions, and was not possible for the hypermixer geometries alone. Non-premixed oxygen enrichment was tested as an alternative in an axisymmetric Mach 3.5 flowpath. It was observed that oxygen enrichment had significant capability to promote stable scram-mode combustion with low losses in total pressure from sources other than combustion effects, as well as capability in controlling the combustion mode through modulation of flow rate. Oxygen enriched flowpaths were successfully modeled using reduced-order techniques.
Hypersonics, Scramjet, Ramjet, Hypermixer, SSTO, Supersonic Combustion, Oxygen Enrichment, Shock-Enhanced Mixing, Cavity Flameholder, Flameholding, Flameholder, Cavity Resonance
University of Illinois - Urbana-Champaign
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