Parametric Study of a Turbojet Engine with Auxiliary Bypass Combustion – The TurboAux Engine

A parametric study of a novel turbojet engine with an auxiliary combustion chamber, nicknamed the TurboAux engine is presented. The TurboAux engine is conceived as an extension of a turbojet engine with an auxiliary bypass annular combustion chamber around the core stream. The study presented in this article is motivated by the need to facilitate clean secondary burning of fuel at temperatures higher than conventionally realized from air exiting the low-pressure compressor. The parametric study is initiated by performing a simple optimization analysis to identify optimal ‘fan’ pressure ratios for a series of conventional low-bypass turbofan engines with varying bypass ratios (0.1 to 1.5). The fan pressure ratios for corresponding bypass ratios are chosen for studying varying configurations of the TurboAux engine. The article is presented in two phases – (i) Phase I presents the simulations carried out to arrive at an optimal configuration of a TurboAux engine and it formulation, (ii) Phase II presents simulations and results to compare the performance of a low-bypass turbofan engine to the TurboAux engine. The formulation and results are an attempt to make a case for charter aircrafts and efficient close-air-support aircrafts.