Characterization of Scramjet Combustor with Transverse Fuel Injection

An experimental study of a three-dimensional Mach 2 scramjet combustor has been conducted. The combustor featured a square cross-section and a three-dimensional expanding section, with optical access on one side. A gaseous ethylene and gaseous oxygen pilot flame was used to ignite the primary fuel in the form of gaseous ethylene (C2H4) at various core air mass flow rates. The primary fuel was injected perpendicular from a combustor wall at just downstream of the pilot flame. Wall pressure measurements were taken along the length of the combustor. The measurements revealed that supersonic combustion was achieved for a limited axial distance downstream of the fuel injection. High- speed flame imaging was used to help characterize the supersonic reaction zone. In addition, C2* and CH* Chemiluminescence data were obtained for a range of equivalence ratios in order to determine heat release patterns. Relative combustion performance was assessed for each case by comparing the wall pressure traces and analyzing the flame visualization data. The results showed that the maximum performance was reached when the overall equivalence ratio was only 0.25 due to poor mixing. This study aims to provide the baseline performance data using normal injection, which will be used to compare combustor performance using different geometries and different injection schemes.