Experimental and numerical study on single droplet breakage in turbulent flow

Abstract

Droplet size distributions in liquid-liquid turbulent flow are determined by droplet breakage and coalescence. The current understanding of these processes are not sufficient. An experimental study on single droplet breakage in turbulent flow, where coalescence can be neglected, is presented in this paper to study the droplet breakage mechanism. A rectangular channel consisting of a pair of opposite steel walls having a series of stationary protuberances to enhance turbulence level, and a pair of opposite glass walls that are smooth to facilitate image capture of the droplet breakage process is used as the droplet breakage channel. The commercial CFD code FLUENT is utilised to simulate the continuous single-phase flow in the droplet breakage channel with interest particularly in the turbulent characteristics such as the turbulent kinetic energy and turbulent energy dissipation rate, as these parameters are closely related to the droplet breakage process. The large eddy simulation (LES) method was used to provide detailed features of the flow. Results from LES were also compared with those from a RANS model (SST k-ω). The simulation results demonstrated that the turbulence level is enhanced across the pair of walls with protuberances. There are more coherent strong vortices in the region close to the wall with protuberances. Some preliminary experimental results on droplet breakage are also presented.