Propulsive Performance of Ideal Detonation Turbine Based Combined Cycle Engine

Abstract

A novel two-mode propulsion system based on detonation combustion, known as a detonation turbine based combined cycle engine (DTBCC), was proposed and thermodynamically analyzed for potential application to aircrafts whose flight Mach number is from 0 to 5. The obvious advantage of the two-mode system is that both modes share the same multidetonation chambers. The quasi-stable total temperature and total pressure for inlet conditions of the turbine could be realized in this hybrid pulse detonation engine. A key parameter (drive area ratio) was defined as the ratio of the outflow area at the head to the cross-sectional area of the detonation chamber. The calculated results showed that the increase of the drive area ratio led to the increase in the mass flow entering the turbine; however, this led to the decrease of the total inlet temperature, the total inlet pressure, and the expansion-pressure ratio of the turbine. Compared with an ideal turbojet engine, the inlet temperature of the turbine in a preturbine hybrid pulse detonation engine with a drive area ratio of 1 was 80 K lower than the former under the same pressure ratio and the same fuel-air ratio. In other words, the increase of the drive area ratio may improve the performance of this hybrid pulse detonation engine. Variation of the pressure ratio was adapted to varied flight Mach numbers by a change of the drive area ratio, which induced the enlargement of the operating range. Finally, a performance model was established to research the components’ characteristics and the propulsive performance of the engine. Preliminary performance estimates suggested that thrust and specific fuel consumption of the two-mode propulsion system were superior to the existing turbine based combined cycle designs.