Numerical study on detonation initiation process in a reverse ignition boosted detonation chamber

To achieve efficient detonation initiation within a short distance and time, an innovative ignition approach based on hot jet ignition and shock wave focusing within a reverse ignition boosted detonation chamber configuration is proposed. Two-dimensional numerical simulations are employed to comprehensively investigate the mechanisms of detonation initiation in H2–air mixtures. The intricate evolutionary processes involving flame acceleration, deflagration to detonation transition, and detonation wave propagation are meticulously analyzed. The numerical investigation reveals that the ignition and propagation processes within this configuration can be categorized into four distinct stages: the ignition and initial flame development stage, vortex development and shock reflection stage, rapid flame acceleration and detonation transition stage, and detonation wave propagation and stabilization stage. These stages correspond to specific sections within the detonation chamber, namely, the ignition chamber, shock reflection section, narrow channel, and main detonation chamber. Flame acceleration is driven by a synergy of wall interactions, vortex entrainment, stretching, and shock reflection. Furthermore, a positive feedback loop between the flame, vortices, and the chamber walls amplifies flame acceleration significantly. The critical moment of initiation hinges upon the convergence of the flame front with the leading shock wave. The formation of large- and small-scale cellular structures under different detonation mechanisms further facilitates stable propagation.