Flow Structure in Rotating Detonation Engine with Separate Supply of Fuel and Oxidizer: Experiment and CFD

Abstract

The experimental and computational investigations of detonation liquid rocket engine (DLRE) operating on natural gas (NG) – oxygen mixture have been performed to examine the impact of the DLRE configuration and fuel supply parameters on the operation process and thrust performance. In experiments, the absolute pressures of NG and oxygen supply were up to 30 and 15 atm, respectively; the mass flow rate of the reactive mixture was varied from 0.05 to 0.7 kg/s; the overall mixture composition was varied from fuel lean (with equivalence ratio 0.5) to fuel rich (with equivalence ratio 2.0). The maximum thrust and the maximum specific impulse obtained in this experimental series was 75 kgf and 160 s, respectively, at the maximum average pressure in the combustor of about 10 atm. It is shown that the increase of static pressure in the combustor results in the increase of both engine thrust and specific impulse. With the growth of the specific mass flow rate of reactive mixture, the operation process, on the one hand, becomes more stable, and on the other hand, the number of detonation waves simultaneously rotating in one direction in the combustor annulus increases. The results of DLRE fire tests were used to explore the predictive capabilities of the Semenov Institute of Chemical Physics (ICP) computational technology designed for full-scale simulation of the operation process in continuous-detonation combustors. Comparison of the predicted results with measurements proved that the calculations accurately predict the number of detonation waves circulating in the tangential direction of the annular DLRE combustor and the chaotic near-limiting operation mode resembling the mode with longitudinally pulsating detonation in the DLRE with CD nozzle extension. Calculations predict with reasonable accuracy both the detonation propagation velocity and detonation rotation frequency. In addition, calculations correctly predict the trends in the variation of DLRE operation parameters in an engine of a particular design. As in the experiments, the use of nozzle extension increases thrust. As for the thrust values, the calculations were shown to systematically overestimate them by at least 27% compared with measurements.