采用可调节表面张力的大密度比、大黏滞系数比格子玻尔兹曼伪势空化模型模拟了近壁区空化泡溃灭过程,并进一步分析了表面张力和初始空化泡内外压差对空化泡溃灭过程中流场分布的影响,探究了表面张力变化对空化泡溃灭时产生的微射流和溃灭压力演化的影响。结果表明:在近壁区空化泡溃灭过程中,随着表面张力减小,加剧了气液交界面的变形,导致微射流更为集中。同时空化泡在溃灭过程中蓄积的表面能减小,在溃灭时刻迅速释放后,减弱了空化泡溃灭强度,空化泡溃灭最大微射流流速和最大压力均随着表面张力的减小而减小,导致空化泡溃灭时间缩短,增加了壁面引起的Bjerknes力,加剧空化泡朝向壁面溃灭的趋势。
Abstract
The process of near-wall cavitation bubble collapse was simulated by using Lattice Boltzmann pseudo-potential cavitation model with tunable surface tension and large density and viscosity coefficient ratio.Furthermore,the influence of surface tension and the initial pressure difference between inside and outside the bubble on the flow field distribution was analyzed,and the relationship between surface tension and maximum micro-jet and collapse pressure was investigated.The results indicate that,with the decrease of surface tension,the range of high-pressure region above the cavitation bubble increases,while the range of low-pressure region between bubble and wall decreases in the final collapse stage.The smaller surface tension intensifies the deformation of the gas-liquid interface,resulting in a more concentrated micro-jet.In addition,more surface energy accumulated during cavitation bubble collapse strengthens the collapse intensity,leading to the increase of the maximum micro-jet velocity and collapse pressure.However,with the increase of pressure difference between inside and outside the cavitation bubble,the effect of surface tension is reduced.Besides,the smaller surface tension leads to the shorter lifetime of cavitation bubble,which increases the Bjerknes force and aggravates the trend of cavitation bubbles collapse towards the wall.
关键词
空化泡溃灭 /
表面张力 /
溃灭压力 /
格子玻尔兹曼方法 /
微射流
Key words
cavitation bubble collapse /
surface tension /
collapse pressure /
lattice Boltzmann method /
micro-jet
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