Investigation of rapid detonation initiation under injection mixing conditions with downstream low-energy ignition strategies

This study investigates the deflagration-to-detonation transition (DDT) under injection mixing conditions using high-resolution numerical simulations and a downstream ignition strategy. We analyze the effects of inflow Mach number , fuel equivalence ratio (ER), ignition duration, and ignition location on mixing and detonation initiation. Results show that lower Mach numbers enhance transverse mixing, while higher Mach numbers facilitate faster detonation onset via stronger shear-induced energy deposition. Near-stoichiometric ER reduces initiation distance and boosts detonation velocity, whereas deviations impede flame propagation . Additionally, a new initiation mechanism emerges under low-energy ignition and low internal energy mixtures: a Mach stem forms during flame acceleration, leading to autoignition behind it. Reflected shocks further promote detonation by intensifying interactions with flame fronts. This mechanism demonstrates a pathway to rapid detonation using minimal ignition energy. Furthermore, appropriate ignition duration and location accelerate upstream flame propagation, with suboptimal placement risking poor mixing and detonation failure. These findings provide comprehensive insights into optimizing conditions for efficient detonation initiation under realistic supersonic combustion systems. • Investigated rapid detonation initiation under injection mixing conditions. • Proposed a low-energy ignition strategy using a Mach stem initiation mechanism. • Explored the effects of inflow Mach number , fuel equivalence ratio, and ignition duration. • Introduced a novel approach to achieve detonation initiation with minimal energy input. • Provided new insights into DDT under low-energy ignition for engineering applications.