Thermodynamic studies of a novel aeroengine concept

Abstract The purpose of the work described is to indicate the potential of a high-speed, spark ignition compound-turbocharged engine as an alternative to the gas turbine powered turboprop. Using relatively simple thermal cycle models, it is possible to show that such a compound-turbocharged engine should be capable of achieving very high thermal efficiency levels. A more sophisticated model of this engine type confirms these findings. It proves more difficult to estimate the power-weight ratio, but the specific power output of such an engine, measured in units of kW/1, is shown to be very high. In addition, such a thermally efficient engine type will permit a much reduced take-off fuel payload. As well as modelling the compound-turbocharged engine itself, comparisons are also made with the conventional gas turbine. The study focuses on propeller shaft input powers in the region of 1 MW. A suitable design strategy for the new engine type is discussed, including the requirement for a lightweight, continuously variable transmission system. At present, it is intended to employ a high-speed electrical transmission system for this purpose, and this relatively new technology is briefly highlighted.