Experimental Investigation of Ligament Formation Dynamics of Thin Viscous Liquid Film at Spinning Disk Edge

The ligament formation and break-up process of thin viscous liquid film at the spinning disk edge were performed experimentally. The regression models for ligament number, tail end diameter of ligament, and mean diameter of droplets were proposed. Despite the velocity slippage of rotary cup atomizers being smaller than that of the disk atomizer, it will not improve the atomizing characteristics. The tail end diameter of ligaments and the size of droplets decrease with increasing rotational speed, while liquid flow rate shows smaller influence on the tail end diameter and droplet sizes. For the break-up of a ligament in the centrifugal field, the connected region between joints presents as dumbbell structures, and the dumbbell structures may contract from both ends to the middle for further integration. Despite the capillary wavelength for the break-up of a ligament being about 3.15 times of the ligament diameters due to ligament stretching, the actual dominant mode is the short-wave mode.