Effect of pressure wave disturbance on auto-ignition mode transition and knocking intensity under enclosed conditions

摘要: Pressure wave propagation behavior is an essential feature for the combustion under enclosed conditions, e.g. internal engines. Previous work by Pan et al. (2016) and Yu (2015) showed that pressure disturbance not only affects hot-spot formation knocking origin, but also induces detonation through a coupling mechanism between flame front. On this basis, study further investigates role of in auto-ignition mode intensity means detailed numerical simulations with stoichiometric H2/air mixture. Firstly, waves different levels strength have been obtained adjusting ignition temperature hot kernel. It shows as raised at each initial temperature, decreased monotonously, declining compression ratio rise caused disturbance. Secondly, three modes observed variations strength, i.e. detonation, mixed supersonic deflagration. As weakness there transition from to deflagration, accompanied rapid decreases peak, obvious pre-flame partial reaction significant increases front speed. These observations are still maintained elevated conditions. Finally, such computations summarized non-dimensional Bradley's diagram. The results show both thermodynamic state can affect intensity, modifications mainly transition. This qualitatively consistent distribution regimes diagram, even though some deviations do exist because diagram constructed on basis initially non-reactive flows.