Effects of slot throat width on two-phase <i>n</i>-decane/air rotating detonation engine

In this paper, three-dimensional numerical simulations are conducted for rotating detonation combustion fueled by two-phase n-decane/air mixtures. The converging–diverging inlet configuration with various slot throat widths (0.5, 1.0, 1.5, and 2.0 mm) is considered. The influence of slot throat width on the flow field structures, pressure feedback, total pressure gain, and theoretical model of a design parameter (L/hD) for the rotating detonation chamber (RDC) are discussed. The simulation results show that with the increase in the slot throat width, the evaporation distance of unburned droplet increases, and the laminated structure with double detonation front is observed, which leads to the local uncouple of rotating detonation wave (RDW) and slightly decreases the RDW velocity. In addition, strong reverse shock waves are found with slot throat width of 1.5 and 2.0 mm. The undisturbed area decreases from 97% to 59%, which indicates that the slot throat width has a significant impact on the pressure feedback. Moreover, the total pressure loss mainly comes from the reverse shock wave, the normal shock wave, and the oblique shock wave. The total pressure gain increases linearly with the increase in the slot throat width. Positive total pressure gains of 2.6% are obtained with slot throat width of 2.0 mm. Furthermore, through theoretical analysis, the design parameter (L/hD) is modeled, three critical pressure ratios are derived, and the result shows that the ideal design interval of the RDC should be located between the second and the third critical pressure ratios. The simulation results can provide guidance for designing the two-phase RDC.