Numerical Estimate on High-Performance Operation of Pulse Detonation Engine

Abstract

Pulse detonation engine (PDE) is a promising propulsion device for aerospace, whose are expected both assignment to a next-generation supersonic transport (SST) as an air-suction-type engine and application as a rocket motor in the form of loading fuel and oxidizer (PDRE: Pulse Detonation Rocket Engine). The features of PDE are as follows: (1) The complex compressor applied in turbojet is unnecessary in the least because combustion is intermittently arisen as a self-sustaining detonation-wave propagating inside a detonation-tube and the high-enthalpy of the burned gas produced by combustion is utilized for generating thrust, and in consequence the potentialities of constructing simple engine system is anticipated. (2) The high-flexibility on operation range is possessed; the generation of high specific impulse is not only theoretically possible, but the flight-speed from zero-speed at takeoff to Mach 5 can be covered by single engine alone. (3) The high-thermal efficiency (60~80%) can be generated if from the high pressure to the thermal energy by supersonic expansion will be utilized; the thermal efficiency of PDE will be far superior to that of the jet engine. The reason is that PDE gives nearly Humphrey-cycle combustion process whereas the jet engine and the gas-turbine engine give Brayton-cycle combustion process.In the present study, the performances of PDE were numerically estimated with detailed chemical reaction model. Flight altitude, flight Mach number, PDE-tube length and fuel-injection forms, i.e. equivalence ratio and distribution of equivalence ratio were altered as operational parameters. In consequence the following possibilities were suggested: The PDE-operation in the lower fuel quantity than stoichiometric mixture gave the higher performances; thrust per mass flowrate of fuel and specific impulse on fuel density, than those in stoichiometric mixture. Moreover, the partial fuel-injection PDE-operation under optimizing fuel-injection form; the equivalence ratio of the head-end side (=1.0), that of the open-end side (=0.0) and the mean equivalence ratio in PDE-tube (=0.1), was anticipated to giving the highest-performances for various flight altitudes, flight Mach numbers and PDE-tube lengths.