Kinetic Enhancement of Microchannel Detonation Transition by Ozone Addition to Acetylene Mixtures

Abstract

The kinetic acceleration of deflagration-to-detonation transition (DDT) of acetylene/oxygen mixtures at lean conditions in a microchannel is investigated using ozone addition. Equivalence ratios and ozone concentration are varied to understand the thermal and kinetic impacts, respectively, on DDT transition. The addition of ozone is found to drastically reduce the DDT time and onset distance via kinetic enhancement. The results show that, with a small amount of ozone addition, the DDT time is reduced by up to 77.5%; whereas it only slightly increases the Chapman–Jouguet velocities by 6.7%. Moreover, the addition of 1% ozone extends the DDT limit from equivalence ratios of 0.3 to 0.2. Furthermore, it is observed that ozone addition has a much larger effect on DDT time than the increase of the equivalence ratio. The present results suggest that, for accelerating DDT, the kinetic effect via ozone addition is much greater than the thermal effect. By using the ozone dissociation chemistry with an acetylene kinetic model (HP-Mech), the kinetic effect of ozone on DDT acceleration is examined. The present finding provides new insight into controlling engine knocking and detonation transition in detonation engines.