Experimental study on splash phenomena of liquid jet impinging on a vertical wall

Abstract

In this study, the splash phenomena of a plain orifice jet impinging on a vertical wall were examined. Experiments were carried out by changing the jet speed (i.e., inlet pressure) and the distance of a vertical wall with rounded and sharp-edged nozzles of different diameters, and the splashed fraction was measured by weighing the mass drained on the vertical wall. In addition, the breakup of the liquid jet and the flow patterns resulting from the jet impinging on the vertical wall were visualized. By increasing the velocity of a liquid jet emerging from a rounded nozzle, the Rayleigh, first wind-induced, and second wind-induced regimes could be observed in order. For the cavitating jet, the jet velocity became significantly larger than the volume flow rate divided by the nozzle area. Nevertheless, the trends of jet breakup as well as the splashed fraction results between the rounded and sharp-edged nozzles were similar for the same jet velocity. The splashed fraction reached its maximum value when small droplets resulted from the secondary breakup of large fragments started impinging on the vertical wall. In addition, the jet velocity at which the maximum splashed fraction attained decreased with increasing distance of the vertical wall from the nozzle exit. These experimental results were explained qualitatively in terms of the conditions of the liquid jet, breakup regime, drop impact, and splashing phenomena.