AN EXPERIMENTAL INVESTIGATION ON LIQUID SHEET BREAKUP DUE TO PERFORATIONS IN IMPINGING JET ATOMIZATION

Abstract

In this work, atomization of the liquid sheet formed by two like-on-like impinging liquid jets is studied experimentally. The primary focus of this study concerns sheet breakup due to the formation and growth of perforations on the liquid sheet. In this mode of atomization, perforations or holes originate at a location where the liquid sheet becomes thin due to stretching. As time elapses, these perforations will grow in size and move either toward the bottom or toward the rim of the sheet. Depending on the initial location of their formation, these perforations either interact with the rim of the sheet or with other surrounding perforations and disintegrate the sheet into ligaments, which further disintegrate into drops. The phenomenon of perforation formation and growth is captured using a high-speed backlight imaging technique and processed using in-house-developed image processing algorithms based on MATLAB. The effect of liquid properties and Reynolds number on the growth of perforations is studied in this work. Based on the experiments conducted in this study, perforation-based atomization is broadly classified into three different modes. In the first mode, a single perforation interacts with the rim and disintegrates the sheet into ligaments. In the second mode, two or more perforations interact, and their common area of interaction is disintegrated into ligaments and droplets. In the third mode, the liquid sheet breaks up due to perforation interaction with impact waves. Studies on atomization behavior of the liquid sheet at high ambient pressure up to 0.8 MPa revealed improved atomization.