THERMODYNAMICAL EFFICIENCY OF A DETONATION ENGINE

Abstract

An attempt has been made to analyze qualitatively and quantitatively the thermodynamic cycle of detonative combustion and to compare it with the Otto and Brayton cycles in order to establish the degree of its thermodynamic perfection. A comparison of the thermodynamic cycles of Otto, Brayton, and detonation was carried out for equivalent Carnot cycles, which has the same degree of thermodynamic perfection as the investigated cycles. To determine the parameters of the detonation cycle, the classical detonation theory based on the laws of thermodynamics and gasdynamics was used. It is shown that the detonation cycle in comparison with the cycles of Brayton and Otto has larger entropy at the end of the heat supply and smaller one at the end of the heat removal. That means it has a higher mean-integral temperature of heat input and a lower mean-integral temperature of heat removal. Thus, in the range of characteristic values of the adiabatic index k, the temperature at the end of the heat input process in the detonation cycle exceeds the Otto cycle temperature by about 7–15 %. Consequently, the detonation cycle is thermally more efficient, since the thermal efficiency of the cycle increases with the expansion of the temperature boundaries of the equivalent Carnot cycle.