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 efe ciencies. To evaluate this parameter from available data of direct connect combustor experiments, ideal nozzle calculation was carried out for each stream tube, starting from the data at the combustor exit, and the results were integrated across the nozzle exit to obtain the efe ciencies and performance parameter. The relative importance of heat release and aerothermodynamic losses were compared for various cone gurations of the fuel injectors and combustor ducts. For e ight Mach numbers less than 7, the heat release had a stronger ine uence on the performance than the losses. The optimum length, where the effects of both effects canceled each other, was 15 ‐20 times the e ow section width for the rectangular section combustor with perpendicular wall injectors.