Effect of the air mass flow rate on coalair twophase rotating detonation waves

A lot of studies on rotating detonation engines have been carried out due to the theoretically higher thermal efficiency compared with traditional deflagration engines. However,there are few investigations reported on gassolid twophase rotating detonation engines which may be used as solid ramjets. In this paper,twodimensional numerical simulations based on a nonpremixed coalair rotating detonation engine were carried out. The unsteady viscous model with volumetric reaction was used for the gas phase,the discrete phase model was used for the solid phase,and the kinetics/diffusion limited rate model was used for the surface combustion of coal. The effect of air flow rate on the rotating detonation wave was studied. The working characteristics of the rotating detonation engine under different modes were analyzed and the numerical simulation results were verified by experiments. Results show that the calculated velocity and flow field of the rotating detonation agree well with the experimental results. The layers between air and particles could not completely coincide with each other because the particle injection velocity was lower than air injection velocity,and thus the local equivalence ratio before the detonation wave was higher than the global equivalence ratio. As the air mass flow rate increased from 38.14 kg/s to 114.40 kg/s,the velocity and temperature peak of the detonation wave first increased and then decreased,and pressure peak increased gradually. The detonation velocity reached the maximum and the mode transition process occurred when the air mass flow rate was 49.03 kg/s. Compared with 〖JP〗single wave mode,the strength and stability of double wave mode were decreased. According to the gassolid phase distribution in the combustion chamber,the flow field during the stable propagation of rotating detonation wave can be divided into three zones:filling zone,detonation product zone and deflagration product zone.