Performance evaluation of scramjet combustors using kinetic energy and combustion efficiencies

A performance parameter of scramjet combustors was introduced on the basis of thrust. It was written in terms of the kinetic energy and combustion eff iciencies. To evaluate this parameter from available data of direct connect combustor experiments, ideal nozzle calculation was carried out for each s tream tube, starting from the data at the combustor exit, and the results w ere integrated across the nozzle exit to obtain the efficiencies and perfor mance parameter. The relative importance of heat release and aerothermodyna mic losses were compared for various configurations of the fuel injectors a nd combustor ducts. For flight Mach numbers less than 7, the heat release h ad a stronger influence on the performance than the losses. The optimum len gth, where the effects of both effects canceled each other, was 15-20 times the flow section width for the rectangular section combustor with perpendi cular wall injectors.