2026-09-22T19:47:10Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/132557 2026-02-20 col_2142_5131 col_2142_14787 com_2142_5130 com_2142_9630 com_2142_234

application/pdf en text Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2026-02-19 without embargo terms The student, August Beck, accepted the attached license on 2025-12-02 at 14:34. The student, August Beck, submitted this Thesis for approval on 2025-12-02 at 15:00. This Thesis was approved for publication on 2025-12-03 at 15:03. DSpace SAF Submission Ingestion Package generated from Vireo submission #23020 on 2026-02-19 at 18:26:01 Flameholding methods for compact hypersonic systems Beck, August David 2025-12-03 Lee, Tonghun Hypersonics Scramjet Ramjet Hypermixer SSTO Supersonic Combustion Oxygen Enrichment Shock-Enhanced Mixing Cavity Flameholder Flameholding Flameholder Cavity Resonance eng 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. 2025-12 Thesis https://hdl.handle.net/2142/132557 Copyright 2025 August David Beck Mechanical Sci & Engineering Mechanical Engineering University of Illinois Urbana-Champaign M.S. Thesis