Numerical investigation on flow and film cooling characteristics of coolant injection in rotating detonation combustor

Abstract

The film cooling is a possible active thermal protection solution for the rotating detonation engines. As the rotating detonation wave is of high periodic and unsteady features, the film cooling characteristics inside the rotating detonation combustor are very complicated. To illustrate the influence of rotating detonation wave on the flow dynamics of coolant jets and the thermal protection performance of film cooling in the rotating detonation combustor, a numerical investigation is performed in the current study, on the base of a simplified physical model wherein only single row of film cooling holes in the axial direction is concerned. The results show that both the blocking effect and oscillating effect occur in the transverse jet injection, upon the impact of sweeping of detonation wave and oblique shock wave. Due to the occupancy of momentary combusting flow invasion into the film cooling hole during one cycle of wave sweeping, the inward flow from the film cooling hole to the combustor chamber is not the pure ‘coolant jet’ but instead of a ‘mixed’ jet. The blocking effect of sweeping oblique shock wave front on the coolant jet injection is significantly weaker when compared to the detonation wave front. With the use of film cooling, the time-averaged temperature on the outer wall of the combustor chamber is reduced effectively, especially in the middle and rear sections of the rotating detonation combustor. The coolant jet injection does not change propagation speed of the rotating detonation wave but reduces a little the peak pressure and peak temperature of each cycle.