油水两相流中超声振动表面油滴的脱附行为

Desorption Behaviors of Oil Droplets Absorbed on an Ultrasonic Vibration Surface in Oil-Water Two-Phase Flows

对油水两相流中超声振动表面油滴的脱附行为进行数值模拟及微观可视化实验,研究超声作用下油滴的变形及运动状态,探讨声流及空化微射流等机制对油滴脱附行为的强化作用,进而分析入射声压、微射流速度对油滴脱附速率的影响。结果表明:超声作用下油滴受到声流曳力及声流回流产生的剪切力,脱附效率明显提高,且随着入射声压的增大,油滴脱附速度也逐渐增大,当入射声压幅值从0.8 MPa提高到1.4 MPa时,油滴脱附时间缩短41.8%。此外,超声空化产生的微射流也是强化油滴脱附的重要影响机制,贴壁微射流对吸附油滴产生强烈冲击,加速了油滴从壁面剥离,并与声流协同作用下有效加速油滴的脱附过程。

The desorption behaviors of oil droplets absorbed on an ultrasonic vibration surface in oil-water two-phase flows were investigated using the methods both numerical simulation and microscopic visualization experiment.The deformation and motion of oil droplets under ultrasound were studied,and the enhanced effects of acoustic streaming and cavitation micro-jets on the desorption behaviors of oil droplets were also discussed,then the influences of the incident sound pressures and micro-jet velocities on the desorption rate of oil droplets were analyzed.The results showed that the desorption efficiency of oil droplets is obviously improved under the action of ultrasound.That is mainly because that the oil droplets are subjected to the drag force caused by acoustic streaming and the shear force generated by its reflux.The desorption velocity of oil droplets increases gradually with the increase of incident sound pressures.When the amplitude of incident sound pressures increases from 0.8 to 1.4 MPa,the desorption time of oil droplets is shortened by 41.8%.In addition,the micro-jet generated by ultrasonic cavitation is also an important influence mechanism for enhancing the desorption process of oil droplets.The wall micro-jet produces a strong impact on the absorbed oil droplets,which accelerates the oil droplets peeling from the wall surface,and the desorption process of oil droplets is also further accelerated in synergy with the acoustic streaming.