Critical breakup transition characteristics of thin viscose liquid film at spinning disk rim

Liquid film breakup mode at disk rim of centrifuge particle generator directly determines droplet shapes and sizes, which is a key factor to affect product qualities. A critical transition coefficient for spinning disk particle generator was proposed to characterize liquid film breakup transition characteristics from film to ligament, to extend to other breakup modes, and to establish critical equations for transition from direct droplet to ligament, ligament to fully ligament, and fully ligament to sheet. The experimental results of three working fluids and two disks indicated that disk surface wettability played key role for liquid film to become direct droplet or to transit from direct droplet to ligament, which incomplete wetting caused random critical volume flow rate with no direct correlation between disk diameter and critical volume flow rate. Critical volume flow rate increased with increasing disk diameter in fully-ligament and film modes. In general, the increase of liquid flow rate, rotation speed, liquid density, and viscosity drove towards film breakup mode. However, high surface tension force maintained liquid film in direct drop or ligament even at large flow rate and rotation speed. Moreover, increasing disk diameter enhanced both centrifugal force and surface tension and breakup mode did not change unless the force balance was lost.