Numerical simulation of detonation propagation and extinction in two-phase gas-droplet ammonia fuel

Numerical simulations of detonation propagation and extinction in ammonia droplet-laden premixed ammonia–oxygen gas are performed in a 2-D planar channel. The sustained propagation and ultimate quenching of detonation with perturbations from ammonia droplets are observed under lower and larger values of initial droplet number density (N_d,0) and diameter (d₀), respectively. The detonation always quenches under d₀=15 μm. The detonation propagation/extinction behaviour and cell structure are dependent on both d₀ and N_d,0. The positive correlations between droplet volume fraction, inter-phase mass, momentum, and energy transfers and d₀ are more nonlinear than their counterparts of N_d,0. The post-Mach stem region experiences higher-intensity detonative combustion and thus droplet evaporative, accelerative, and heating effects than the post-incident wave region. During the detonation extinction process, the detonation wave degenerates into detonative spots which then decouple into shock and reaction fronts; gaseous pressure, heat release rate, and nitric oxide volume fraction peaks decline.