DNS analysis of detonation-turbulence interaction with massless tracer particles: Effects of turbulence length scale

Direct numerical simulations (DNSs) using massless tracer particles with a detailed chemical reaction mechanism are performed for detonation-turbulence interaction (DTI) in a stoichiometric hydrogen/oxygen mixture, and the effects of different turbulent Reynolds numbers on DTI are investigated in detail. The use of massless tracer particles is useful because they can help obtain the flow properties along actual gas moving paths. This can help evaluate the change in front of and behind the shock, and the subsequent influence on combustion. Five turbulent conditions are considered with different turbulence properties specified by the turbulent Reynolds and Mach numbers. The results show that the regular and periodic structure of detonation, as observed in a quiescent mixture, is distorted by turbulence, depending on the turbulent Reynolds and Mach numbers. The Taylor microscale vortices obtained from the temporal–spatial averaging are compressed and expanded behind the shock and flame in the non-turbulent detonation, respectively. Commonly, in both turbulent Mach number cases, the Taylor microscale vortices are strongly compressed as the turbulent Reynolds number decreases. Through analysis using massless tracers, the detonation peaky structure is well demonstrated, which cannot be captured by temporal–spatial averaging as considered in our previous study. The ensemble-averaged profiles of each species elucidate that the reaction progresses faster as the turbulent Reynolds number decreases. By analyzing the massless tracer particles, the underlying mechanism of the promoted reaction is clarified using the shock intensity as an indicator of shock compression. As the turbulent Reynolds number decreases, the shock intensity increases with a shorter induction length, which is attributed to stronger compression. Novelty and significance This study is a continuing study of Suzuki et al.2024 PCI. While Suzuki et al.2024 aimed to investigate the effects of turbulent Mach number, this study targets the effect of turbulent Reynolds number. The novelty of this research is to reveal the effects of different turbulent Reynolds numbers through DNSs with tracer particles. The smaller the turbulent Reynolds number is, the stronger the detonation structures are distorted. Tracer analysis clarifies the underlying mechanism of reaction promotions as follows. When local inflow velocity into shock is high, post-shock pressure and temperature increase, which promote subsequent reactions.