Numerical investigation of the operating process in an annular detonation chamber of low diameter

Abstract

Burning in unsteady rotating detonation waves is one of the ways of operating process organization in future aircrafts engines. However, a minimum combustion chamber diameter in which the unsteady rotating detonation process can be actualized is a significant limitation of such engines. A possibility of hydrogen-air mixture burning in an annular chamber with a diameter of 78 mm is shown in this paper using methods of three-dimensional computational fluid dynamics. The geometry of the chamber and the modes of its operation were selected, and the influence of the total pressure of air at the inlet was studied. At the pressure of 32 bar, the mass flux in the critical section of the aerodynamic nozzle was 7349.2 kg/(s·m2). It is shown that in a rotating reference frame in which the detonation wave is at rest, streamlines come to the wavefront almost at right angles. This fact allows making simple estimates of the fresh mixture parameters in front of the wave. Comparison with the detonation parameters in a premixed hydrogen-air mixture in the tube showed that the velocity of the detonation wave in the chamber is 0.65-0.74 of the Chapman-Jouguet detonation velocity, and its height is approximately equal to the characteristic size of the cellular structure of the detonation.