Coalescence of Droplets of an Ink Jet (2nd Report, Valuation of Drag Coefficient of Droplets by 2-D Cylinder Model)

摘要

In Hertz type ink jet printers, a liquid jet ejected from a 10 μm capillary tube into air breaks up to droplets, and after, some of the droplets are charged and the remaining non-charged droplets are used as dots for printing. We reported experimental results on the coalescence of droplets in a previous paper. In this paper, the flow patterns around two cylinders were analyzed in order to examine the drag of droplets by using a 2-D model. Experiments were carried out to visualize the flow past two circular cylinders arranged in a series in a water tunnel. The analytical results of the streamline agree with that of the experimental results qualitatively. The error of analysis and experiments of reduction ratio of drag coefficient between the first and second cylinders is 3.7 in the case of the first coalescence.