To the Question of Energy Use of Detonation Combustion

D URING detonation combustion1 of explosive gas mixtures, immediately after the passing of detonation wavefront (completion of chemical reaction), the products of combustion are in a state (call it state D) that is quite rich in both heat and kinetic energy (i.e., the energy of translational motion). Assuming no losses, the state D of combustion products can be calculated using the classical thermodynamic theory of Jouguet. The propagation speed of detonation obtained in this calculation agrees well with experiment, which confirms the correctness of the thermodynamic theory as the limiting case with no losses. For the combustion products in the detonation wave, such a calculation gives: density is 2–1.7 times greater than that of the initial mixture (approximately (k + 1)/k times greater, where k is the adiabatic exponent, pvk = const, for the combustion products); pressure is approximately 2 times greater than the pressure achieved in a closedvolume explosion; temperature is 10-20% higher than the temperature of a closed-volume explosion (approximately 2k/(k + 1) times higher); speed of translational motion is about 0.4–0.5 times that of detonation propagation, which means that kinetic energy of translational motion reaches 17% of the total energy of the mixture. It is interesting to consider to what extent detonation combustion of fuel allows more efficient energy use. One often comes across proposals for detonation regime of combustion in machines such as a gas turbine. Below we present a thermodynamic analysis of the efficiency of cycles with detonation. We will consider here the essential aspects and only briefly comment about technical viability of cycles, losses that reduce the efficiency as compared to the calculated values, etc.