Effects of inert gas jet on the transition from deflagration to detonation in a stoichiometric methane-oxygen mixture

Detonation is an energetic combustion mode augmenting high flow momentum and thermodynamic efficiency, it has been applied in detonation engines, such as pulse engines (PDEs) rotating (RDEs), they have become potential aerospace propulsion equipment. Recently, fluidic jet-in-cross (JICF) demonstrated experimentally numerically that can accelerate the deflagration-to-detonation transition (DDT) process. Nonetheless, most of previous studies focused on jets using combustible mixture or oxygen, which may bring additional risk for turbulence-generated system engines. In this study, a more safe controllable inert gas (i.e., Ar) JICF, experiments are carried out to investigate effects argon jet enhancement method promoting DDT stoichiometric methane-oxygen mixture. The local concentration, turbulence intensity injection position process systematically examined. Two-dimensional numerical simulations also performed elucidate details evolution. experimental results show generated by promote flame acceleration onset only fast deflagration regime. enhancing effect prominent at higher increasing pressure shorter time. Too long duration increases concentration leads adverse prohibiting occurrence. During initial laminar acceleration, referred slow regime, no be observed. By looking structure jet, vortical features enhance transport mixing between reactants products. interaction reactive travelling wave further induces thus accelerates chemical reaction rate. With time elapsed, injected entrains largely dilutes ambient mixture, restrains DDT. Furthermore, novel dimensionless criterion characteristic parameter Turc proposed, quantitatively analyzing dominate mechanism propagation stage introduced.