A DNS study of detonation in H₂/O₂ mixture with variable-intensity turbulences

Direct numerical simulation with a detailed chemical reaction mechanism is performed for detonation-turbulence interaction in a stoichiometric hydrogen/oxygen mixture. Three turbulences are introduced into detonation with different intensities which are defined by turbulent Reynolds number and turbulent Mach number. The results show that turbulent flow corrugates both shock and flame fronts and makes cellular structures obscure and randomized. The strongest turbulence distorts the shock so strongly that the transverse wave is unclear and cellular structure is destroyed. Time-averaged one-dimensional profiles demonstrate that turbulence promotes the reaction progress. Stronger turbulence produces more intermediate species, by which the chemical reaction reaches completion more rapidly. The turbulent combustion regime indicates that small eddies intrude the flame structure, for which unburned gas pockets are broken into pieces and consumed rapidly. It is consistent with the tendency of the probability density function of induction length, which has only one peak in a smaller value under stronger turbulences, whereas two peaks under the weakest turbulence and without turbulence. Turbulence increases the peak pressure on one-dimensionally averaged structure except for the case where the cellular structure is destroyed. Averaged detonation velocity is strongly correlated with the magnitude of peak pressure, which is the lowest in the strongest turbulence, whereas its deviation increases with turbulent intensities. The absence of the cellular structure, which has been confirmed in optical measurements of rotating detonation engines, could be attributed to the collapse of the cellular structure observed in the strongest turbulence.