A quasi-one-dimensional model of coupled incomplete droplet evaporation and equivalence ratio effects on rotating detonation performance

Concerning the significant deficit of detonation wave speed relative to the Chapman–Jouguet (C–J) speed observed in kerosene-fueled rotating detonation engine (RDE) experiments, this study investigates the impact of incomplete kerosene droplet evaporation and its coupling with the equivalence ratio on the detonation performance in RDEs. A quasi-one-dimensional Eulerian–Eulerian multiphase model is developed, integrating gas dynamics with droplet behavior—including rapid droplet breakup, momentum equilibration, and coupled heat and mass transfer processes. Simulation results reveal that incomplete evaporation leads to significant thermal losses and consequent detonation speed deficits, as a sizable fraction of the fuel remains unvaporized prior to the sonic point. Moreover, the detonation performance is found to be highly sensitive to the overall equivalence ratio; an optimum detonation speed is achieved only at ratios exceeding unity, with the peak shifting to higher values as the initial droplet size increases. This “Peak Detonation Speed Shift with Equivalence Ratio” effect explains the pathological detonation phenomena observed in experimental RDEs, where inadequate atomization and localized inhomogeneities result in substantial deviations from the ideal C–J velocity. The findings underscore the importance of enhanced fuel atomization and uniform mixing for improving the thermodynamic efficiency and propulsion performance of liquid-fueled RDEs.