Turbojet module sizing for integration with turbine-based combined cycle engine

Abstract The turbojet module for a turbine-based combined cycle engine is sized subject to constraints arising from the configuration of its scramjet engine. An existing turbojet engine (TJE) core (compressor, burner, turbine) is scaled for air mass flow rate such that the desired thrust at the handover Mach number is achieved. An aerothermal model for the TJE core is integrated with a supersonic intake and nozzle, which are designed using a method of characteristics code. The intake and nozzle, which are constrained by the ramp angles selected for the scramjet module, are managed by appropriate use of splitter plates. The TJE module is sized by scaling the engine core with matching intake and nozzle designs in an iterative manner until the process converges to an acceptable value of handover thrust. A single operating point at the handover Mach could be found that met the thrust requirement while satisfying the constraints.