Propagation characteristics of AlH3/air gas–solid two-phase rotating detonation wave

Utilizing high-energy solid powder fuel is the key path to enhancing the performance of rotating detonation engines. However, traditional solid fuels have problems such as slow reaction kinetics or long ignition delay, which restrict their energy release efficiency in detonation environments. The thermal decomposition temperature of AlH3 is low, and its hydrogen storage density is high, which can provide a feasible path for gas–solid two-phase detonation. This paper employs the Eulerian–Lagrangian method to solve the gas–solid two-phase detonation problem, and the effects of different parameters on the flow field and detonation wave propagation characteristics are considered. The results show that the detonation wave exhibits two spatially separated heat release zones behind a single shock front. The forward reaction zone is dominated by the H2–O2 homogeneous reaction, while the rearward reaction zone is dominated by the Al(s)–O2 heterogeneous reaction. As the equivalence ratio increases, the wave velocity and pressure first increase and then decrease. The same non-monotonic trend is observed when the inlet total temperature is raised. Excessive equivalence ratio reduces the energy contribution of aluminum combustion, shifting the detonation toward hydrogen-dominated propagation, whereas excessive inlet temperature causes premature AlH3 decomposition ahead of the wave. The inlet mass flow rate monotonically increases the front pressure, but the wave velocity exhibits an optimal range. At excessively low flow rates, aluminum particles burn incompletely; at excessively high flow rates, particles tend to escape through the triple wave point, both of which degrade the effective fuel utilization.