Flow field characteristics and particle path tracking of a hollow rotating detonation engine with a Laval nozzle

Abstract

A statistical particle path tracking method is applied to a hollow rotating detonation engine (RDE) with a Laval nozzle, and the flow field characteristics are investigated. The in-house solver BYRFoam based on OpenFOAM is used, and a large-area outflow field at the tail of the combustor and an array of injection holes are implemented. The influence mechanism of the tail nozzle on the internal and external flow fields of the hollow RDE is revealed. The results confirm that the tail nozzle helps suppress the rotating shock wave of the outflow field, which can make the exhaust plume structure more symmetrical. The influencing factors of the flow field of RDE with nozzle are studied. The results show that the farther the equivalence ratio deviates from 1, the closer the normal shock wave is from the nozzle outlet. The paths of representative flow particles are tracked, and the paths and physical properties of flow particles from different injection areas are obtained and compared. The results demonstrate that the overall movement trend of particles along the circumferential direction is opposite to that of the detonation wave, and some particles entering the combustor from the inner hole enter the virtual inner cylinder. The particle paths of hollow RDE without nozzle and RDE with radial injection method are studied. The results show that the particle circumferential deflection angle is smaller for RDE without nozzle and larger for RDE with radial injection method compared to RDE with nozzle and axial injection. A statistical tracking method for a large number of particles is proposed to obtain the flow characteristics of the gas in the combustor. The results confirm that the average circumferential deflection angle and the average residence time and its dispersion degree of the inner hole gas are larger than that of the outer hole gas. Flow particles with smaller initial radial position coordinates produce more curved particle traces. A thermodynamic statistical method for a large number of particles and the concept of a maximum work–heat ratio are used to analyze the macroscopic thermodynamic cycle characteristics of the gas. The results reveal that the maximum net mechanical work and the maximum work–heat ratio of the outer hole particles are larger than those of the inner hole particles. The gas entering the combustor from the outer hole has a greater proportion of chemical energy converted into useful work and a better expansion effect.