On the Early-Stage Deformation of Liquid Drop in Shock-Induced Flow

Abstract

Breakup of liquid drops in diversified gas flow conditions is widely investigated. The primary interest of previous researchers has been focused on breakup regimes, which depend principally on the Weber number We ¼ ρu2d=σ. Oscillation, bag mode, bag and stamen, multi-wave piercing, stripping, and catastrophic breakup were accepted as main breakup regimes in most early literatures [1, 2]. The early-stage deformation of waterdrop exposed to shock-induced flow is experimentally investigated. High-speed photography is applied to record the development of the drop, and numerical simulations are performed as well to assist the understanding of deforma- tion dynamics. A parameter reflecting the accumulation speed induced by shearing of the gas flow is proposed in the research. Two mechanisms, the pressure mechanism and the shear mechanism, are identified responsible for the early-staged deformation. It is found that the former is the main cause of the drop-scale flattening, while the latter might count for formation of the small bulges and rings. The bulges and rings are the main sources of the mist in the flow.