  Two-dimensional wedge-stabilized oblique detonations in stoichiometric and
fuel-lean H2/O2/Ar mixtures with water mists are studied with
Eulerian-Lagrangian method. The effects of water droplet mass flow rate on flow
and chemical structures in the induction zone, as well as physical / chemical
roles of water vapor, are investigated. The results show that the oblique
detonation wave (ODW) can stand in a range of water mass flow rates for both
stoichiometric and fuel-lean mixtures. With increased droplet mass flow rate,
the deflagration front in the induction zone is distorted and becomes
zigzagged, but the transition mode from oblique shock wave (OSW) to ODW does
not change. Moreover, the initiation and transition locations monotonically
increase, and the OSW and ODW angles decrease, due to droplet evaporation and
water vapor dilution in the induction region. For fuel-lean mixtures, the
sensitivity of characteristic locations to the droplet loading variations is
mild, which signifies better intrinsic stability and resilience to the oncoming
water droplets. The chemical explosiveness of the gaseous mixture between the
lead shock and reaction front is studied with the chemical explosive method
analysis. The smooth transition is caused by the highly enhanced reactivity of
the gas immediately behind the curved shock, intensified by the compression
waves. Nonetheless, the abrupt transition results from the intersection between
the beforehand generated detonation wave in the induction zone and OSW.
Besides, the degree to which the gas chemical reactivity in the induction zone
for fuel-lean mixtures is reduced by evaporating droplets is generally lower
than that for stoichiometric gas. Also, physical and chemical effects of water
vapor from liquid droplets result in significant differences in ODW initiation
and morphology.
