Effects of Evaporation Modeling on Kerosene–Air Oblique Detonation

A variety of droplet evaporation models with different levels of complexity are available to numerically simulate spray two-phase flows, but their effects on the characteristics of gas–droplet oblique detonation waves (ODWs) have not been well understood. In this study, wedge-induced kerosene-droplet–air ODWs are simulated in a Eulerian–Lagrangian framework with six evaporation models, including five equilibrium models based on various assumptions on liquid thermal conductivity and a nonequilibrium model. The effects of droplet evaporation to the initiation and surface instability of ODWs are highlighted when compared to their single-phase counterparts. In kerosene-droplet–air ODWs simulated with different evaporation models, it is found that the overall flow structures and shock angles are not sensitive, but the initiation length, the combustion rate, and the initiation patterns vary significantly. Through tracking the droplet evaporation histories, the above differences are attributed to the slowing down in evaporation rate when finite-rate liquid heat conduction, internal recirculation, and surface nonequilibrium are considered successively in the model. The formation mechanisms of three initiation patterns caused by the strength variations of interior detonation and shock waves under different evaporation rates are revealed as well. The importance of accurate evaporation modeling to numerical investigations of gas–droplet ODWs is emphasized.