超声驻波场中油滴失稳破碎特性仿真研究OA

The phenomenon of droplet destabilization and subsequent breakup in ultrasonic standing wave fields is of paramount significance in various domains,including spray combustion and thermoacoustic coupling.Based on the highly nonlinear spatial distribution of standing wave acoustic fields,this study employs the COMSOL Multiphysics simulation platform to construct a visualized and quantifiable model of the acoustic field.By intergrating the phase-field method to accurately track the air-droplet interface,the destabilization process and breakup characteristics of single and multiple droplets under the action of ultrasonic standing waves are investigated.Additionally,the impact of acoustic pressure amplitude and frequency in the ultrasonic standing wave field on the breakup time of various alkane droplets is studied.The results show that the droplet breakup velocity is closely related to its position in the acoustic field.Specifically,droplets at the pressure node break up the fastest,followed by those at the upper antinode,while droplets at the antinode break up the slowest.For instance,a 2.8 mm n-heptane droplet experiences a breakup time of merely 1.16 ms at the node,2.07 ms at the upper antinode,and 3.62 ms at the antinode.Furthermore,the breakup process of droplets at the indentical positions accelerates significantly with increasing acoustic pressure intensity.For large-molecule alkane droplets,increased surface tension makes breakup more difficult.Nevertheless,at the pressure node where droplets are primarily subjected to acoustic radiation forces,the increase in breakup time is not significant.The study also reveals evident axial attenuation in the acoustic field,with higher initial frequencies leading to faster attenuation.Consequently,the acoustic pressure gradually decreases along the axial direction downward,a distribution characteristic unfavorable for droplet deformation and breakup.This work elucidates the intrinsic relationship between the destabilization and breakup characteristics of alkane droplets and the acoustic field parameters in ultrasonic standing wave fields.The numerical results enhance the understanding of the mechanism of acoustic-induced droplet breakup and offer noval insights and methodological references for applications such as acoustic field-assisted spray combustion and thermoacoustic coupling.