On the evolutions of induction zone structure in wedge-stabilized oblique detonation with water mist flows

TL;DR

This study investigates how water mist flows influence the structure and stability of wedge-stabilized oblique detonations in hydrogen-oxygen mixtures, revealing effects on wave angles, transition locations, and chemical reactivity.

Contribution

It provides new insights into the physical and chemical roles of water vapor in detonation dynamics, especially regarding induction zone evolution and wave transition behavior.

Findings

Oblique detonation waves can persist across a range of water mass flow rates.

Increased water droplets distort the deflagration front and alter wave angles.

Fuel-lean mixtures show greater stability and resilience to water droplet effects.

Abstract

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.