Influence of surface and edge profile of a spinning disc on its atomization characteristics in direct drop mode

A spinning disc in direct drop regime is useful for contacting applications using one stream as drops. Here, we present a systematic probe into the effect of several edge and surface modification strategies on droplet characteristics. The characteristics of interest in this study are mean sizes of primary and secondary drops and their spread around respective mean values, and the evenness of circumferential distribution of drops. Exposure controlled static imaging is used to obtain blur free images in high resolution. Concentric grooving on surface offered stable film under limited flow condition, improves circumferential distribution, and significantly eliminates secondary drop formation. Serration at the disc edge controls the pitch of the drop detachment points, a feature naturally unique to only ligament mode. A new scale named maldistribution index (MI) is proposed to quantify circumferential distribution of released droplets.