Flame-Stabilization of Liquid and Gaseous Surrogate Fuels in a Scramjet Combustor

This experimental study investigates the flame-stabilization and thermal choking location of aviation kerosene and various well-defined fuel surrogates in a direct-connected vitiated tunnel with a model scramjet combustor with an inlet Mach number of 2.2 and a stagnation temperature of 1500±30 K. The goal is to characterize a backwards-swept strut-cavity configuration with liquid and gaseous fuels in combustion experiments and explore the influence of injector diameter on flame stabilization. The model consists of a flush-wall injector with a backward-swept strut located upstream of a cavity flameholder. The stabilization mode and heat release profile of the reference jet-fuel is examined and compared to n-dodecane at global equivalence ratios of ϕ=0.3, 0.45 and 0.6. Furthermore, a comparison is made with combustion of gaseous mixtures composed of methane and ethylene at ϕ=0.3. Results show clear differences in the thermal choking limit and choking location between the different fuels. The analysis indicates that the combustion of liquid fuels injected at room temperature is dominated by vaporization and mixing timescales rather than chemical kinetics.