Experimental Study of Ethylene Combustion in a Scramjet Combustor

In this paper the ignition characteristics of gaseous ethylene hydrocarbon fuel is investigated in the supersonic clean airstreams experimental facility with a resistance heater. The generic cavity flame holder is used to create recirculation and promote the fuel/air mixing at the lower wall of the combustor. Three different injection concepts are considered in this research: (1) ethylene injection upstream of the cavity; (2) ethylene and hydrogen injection upstream of the cavity simultaneously; (3) ethylene injection preceded by pilot hydrogen injection. The pilot injection showed to be a supportive tool for holding the flame of the main normal ethylene fuel injection. Therefore, using pilot hydrogen injection and cavity configuration necessitates optimizing the combustor length to ensure the complete combustion and the full liberation of the chemical energy stored in the fuel before exiting the combustor. The present study proved the possibility of igniting the ethylene and maintaining its flame in the supersonic airstreams.