Stalling regimes of water droplet breakup in shock waves

The paper is a summаry of experimental studies of water droplet breakup in the flow behind the shock wave in the range of gas flow velocities 40 $\le U\le$ 175 m/s. A change between two different mechanisms of stalling breakup of the droplet occurs in this range of velocities, with domination of the inertia force in the case of droplet deformation and viscous friction force in the case of boundary layer shedding. The analysis of the change in the breakup mechanisms is based on a vast pool of observations and quantitative data on droplet dynamics and delays of its breakup obtained by a high-speed method of visualization with a stroboscopic laser source of light. A physical model of the process is constructed on the basis of experimental data and results of the parametric analysis, and criteria of the change in stalling mechanisms of droplet breakup are derived.