Investigations on ethylene combustion in a scramjet combustor using resistance heaters

In this article, the ignition characteristics of the gaseous ethylene hydrocarbon fuel is investigated in a supersonic clean airstream experimental facility with resistance heaters. A generic cavity flame holder is used to create a recirculation region and promote the fuel/air mixing at the lower wall of the combustor. Three different injection concepts are considered in this research: (a) ethylene injection upstream of the cavity; (b) ethylene and hydrogen injection upstream of the cavity simultaneously; and (c) ethylene injection preceded by pilot hydrogen injection. The pilot injection is 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 complete combustion and full liberation of the chemical energy stored in the fuel before exiting the combustor. This study proved the possibility of igniting the ethylene and maintaining its flame in the supersonic airstreams.