Experimental and numerical analysis of rotating detonation in liquid hypergolic propellants

This study employed an impinging-jet injector with 62 impinging pairs and an annular combustion chamber to conduct experiments on rotating detonation using liquid monomethylhydrazine (MMH) and nitrogen tetroxide (NTO). The experiments successfully achieved self-sustained rotating detonation waves spontaneously formed by hypergolic propellants, and observed detonation initiation, single-wave mode, and dual-wave mode. Furthermore, numerical simulations based on the Reynolds-averaged Navier–Stokes/large eddy simulation hybrid model and the discrete phase model were performed, successfully reproducing the hypergolic rotating detonation phenomenon. Experimental results revealed low-amplitude pressure oscillations in the combustion chamber prior to rotating detonation formation. The detonation waves in liquid MMH–NTO were found to develop from low-amplitude combustion instability, with the deflagration-to-detonation transition process exhibiting progressive characteristics. Numerical simulations revealed a transient deflagration process following the detonation wave. As the upstream droplets evaporated and absorbed heat, the temperature drop weakened the deflagration. Prior to the subsequent detonation wave arrival, the deflagration intensity attenuates to its minimum level, thereby storing energy to sustain stable detonation propagation while effectively suppressing the pre-wave deflagration characteristic. Energy release in hypergolic rotating detonation concentrates in the high-density droplet zone at the combustor head, exhibiting peak combustion intensity. The detonation wave triggers abrupt pressure and temperature surges that induce rapid propellant droplet evaporation and reactant compression. The compressed reactants undergo near-constant-volume combustion with fast energy release, driving supersonic detonation wave propagation.