The effects of nozzle plate defects on droplet jetting behavior and directionality are studied numerically and experimentally. In particular, we examine the mechanism responsible for the phenomenon of tail-hooking, where break-up occurs at a point on the side of the nozzle, rather than on the central axis. We investigate how nozzle defects lead to this breaking of jet axisymmetry. Fully three-dimensional simulations through nozzle geometry were performed using Flow3D software are compared with experiments performed on a large scale model of a drop on demand inkjet print-head. For nozzles plates in which the outer surface is not perfectly aligned with the nozzle axis, we observe asymmetric break-off. The directionality of main droplets is not greatly affected by the nozzle angle but the behavior and directionality of the satellite droplets is dramatically altered. ©2013; Society for Imaging Science and Technology.
