Shock tunnel experiments are presented that examine combustion modes of ethylene and a 64/36% ethylene/methane mixture under Mach 8 flight-representative conditions within an axisymmetric scramjet cavity combustor. Combustion modes (scram-mode and dual-mode) are presented via streamwise pressure measurements and visualized via planar laser-induced fluorescence (PLIF) of the hydroxyl (OH) combustion radical in the combustor exhaust plume. Ethylene-fuelled experiments developed scram-mode combustion under lean fuelling, whereas increased fuelling anchored combustion to the fuel injector wake. Further fuelling increases to stoichiometric levels developed dual-mode combustion. Exhaust OH PLIF indicated ethylene scram-mode combustion developed combustion products primarily in the wall-adjacent regions, whereas asymmetric flowfields were noted for the dual-mode. The addition of methane inhibited reactions, with no scram-mode combustion observed at even fuel-rich conditions. Higher fuelling rates developed dual-mode combustion with comparable pressure rises to the ethylene-fuelled dual-mode cases. OH PLIF indicated reduced concentration of OH for the ethylene/methane mixture. This work confirms the retarding influence of methane upon the reaction pathways of ethylene and reaffirms that fuels do not react independently in gaseous mixtures.
Experimental Scramjet Combustion Modes of Hydrocarbon Mixtures at Mach 8 Flight Conditions
AIAA Journal ; 58 , 12 ; 5117-5122
2020-10-15
6 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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