Detachment of droplets by air jet impingement

Surface cleaning using air jets is an appropriate method to remove particles from surfaces especially when cleaning by mechanical methods is not suitable. The detachment behavior of droplets using an air jet is not necessarily the same as solid particles and there is a lack of studies regarding this behavior. In this article, the detachment of droplets on a plastic substrate by air jet impingement was investigated experimentally. Droplets of two different size ranges were impinged by an air jet with different impinging angles. For micrometer-sized droplets, a smaller horizontal velocity was required to detach large droplets. Moreover, the horizontal velocity required to detach 50% number fraction of droplets decreased when the air jet impinging angle increased. Millimeter-sized droplets split into many portions. Most portions remained on the substrate and only a few were resuspended. The remaining portions were distributed in a fan shape, with larger droplets traveling further on the substrate. A linear lower bound of traveled distance was observed. Due to the splitting and the small fraction of resuspension, it should not be expected that air jet cleaning of droplets is the same as that for solid particles.