Theory and calculation of parameters of the detonation engine thermodynamical cycle

Abstract

The ideal thermodynamic cycle of a detonation engine is substantiated and a method of computing the engine parameters is presented. In the ideal cycle the processes of gas compression and expansion are adiabatic. It is shown that low thermodynamic effectiveness of the detonation engine can be explained by significant wave losses of the total pressure in the shock wave and the entropy increase. The advantage of the engine in comparison with other thermal machines is the capability of obtaining a high value of absolute energy of the gas flow to do the work of gas expansion. While analyzing the thermodynamic cycle it is assumed, like in the gas turbine engine theory, that the characteristics of gas condition are determined by the parameters of stagnation subsonic flow in the sections corresponding to the beginning and the end of the processes making up the cycle. Heat supply downstream of the shock wave takes place in the subsonic flow in a constant-pressure process. Consideration of the cycle with stagnation parameters significantly simplifies its analysis and gives a fuller picture of its energy. A formula for calculating the coefficient of thermal efficiency of the ideal cycle of a detonation engine is presented as a function of the specific speed of propagation of the stabilized shock wave. It is shown that the ideal thermodynamic cycle of a detonation engine is described by two adiabatic curves, an isothermal curve determining huge wave losses, and two isobaric curves. The work of gas expansion in a detonation engine can be implemented both for obtaining the moving force of a vehicle and in industry, e. g., for metal hardening and cutting, production of high-hardness artificial diamonds, geophysical investigation.