Direct numerical simulation of detonation–turbulence interaction in hydrogen/oxygen/argon mixtures with a detailed chemistry

Abstract

Direct numerical simulation is conducted to address the detonation–turbulence interaction in a stoichiometric hydrogen/oxygen/argon mixture. The argon dilution rate is varied so that the mixture composition is 2H2 + O2 + 7Ar and 2H2 + O2 + Ar to discuss the effects of cell regularity on the sensitivity to turbulence. Turbulent Reynolds number and turbulent Mach number are taken to be common for both mixtures. The results show that the shock and flame of detonation in both mixtures are significantly deformed into corrugated ones in the turbulent flow, producing many small unburned gas pockets. However, one-dimensional time-averaged profiles reveal the different sensitivity of the mixtures: in the highly diluted mixture (2H2 + O2 + 7Ar), the reaction progress is not much influenced by turbulence, whereas in the less-diluted mixture (2H2 + O2 + Ar), the reaction takes place more rapidly with turbulence. Analysis of the properties of turbulence and turbulent fluctuations in the detonations clarifies that the direct contribution of turbulence to the flame front is weaker; there is no clear correlation between the heat release and the curvature of the flame. On the other hand, a broader Mach number distribution just upstream of the shock front creates more hot spots in the less-diluted mixture, which results in a shorter induction length. These results indicate that the main contribution of turbulence is creation of different shock strength, which could lead to different reaction rates depending on the cell regularity.