An Experimental Investigation on Forced Ignition Characteristics of Hydrocarbon Mixture Fuel in Scramjet Combustor

The scramjet combustor model installed with a micro-burner torch and cavity was tested in a combustion wind tunnel facility at the Kakuda Space Center of the Japan Aerospace Exploration Agency (JAXA). A methane-ethylene mixture gas fuel (36%/64%) was injected directly into the cavity. The aim of this dissertation was to clarify the forced ignition characteristics of the hydrocarbon mixture fuel in scramjet combustors. First, the effect of the fuel supply rate on the forced ignition limits was experimentally evaluated followed by an evaluation of the effect of the torch gas temperature on the forced ignition limits. In this study, the OH* chemiluminescence emission was measured to determine the ignition in the cavity. The torch gas entered directly into the shear layer between the main and recirculation flows within the cavity. When the methane-ethylene mixture fuel reached the leading edge of the cavity where air was plentiful, the mixture fuel was ignited in the shear layer. The results indicated that it was necessary to evaluate the ignition within the recirculation zone as well as in the shear layer.