通孔平板附近空化泡动力学特性数值模拟研究

Numerical study on dynamic behaviors of cavitation bubbles near through-hole flat plate

在空化清洗过程中,清洗的程度与空化泡到孔板的距离和空化泡最大半径之间的比值息息相关。然而对通孔平板附近的空化泡动力学研究大多局限于空化泡形态和射流方向,对于射流强度以及演变周期的关注很少。本文基于开源流体动力学软件OpenFOAM平台,利用已建立的两相可压缩空化泡动力学模型对带有通孔平板附近的空化泡多周期演变动力学特性进行了深入地研究。通过分析发现,空化泡溃灭形成的液体射流到达孔心时的最大速度随着γ(特征距离)的增加而减小;随着ε(相对大小)的减小,液体射流达到孔心的最大速度增加;空化泡第一次溃灭时的最小半径均随着γ和ε的减小而逐渐增大,空化泡溃灭的剧烈程度有所减缓,第一次溃灭周期有所延长。

The effectiveness of cavitation cleaning process is closely linked to the ratio of the distance between a cavitation bubble and the orifice plate to its maximum radius in this process.However,most of the previous studies on cavitation bubble dynamics in the vicinity of a through-hole flat plate were limited to the factors such as morphology and jet direction,with little attention given to jet strength or evolutionary period.In this work,a two-phase compressible cavitation bubble dynamics model is used to study the multi-period evolution dynamics of cavitation bubbles near a flat plate with a through-hole,based on the open source fluid dynamics code OpenFOAM.Simulation results reveal that the maximum velocity of the liquid jet,formed by cavitation bubble collapsing,decreases as the distance parameterγincreases when it reaches the center of the hole.As the size parameterεdecreases,this liquid jet's maximum velocity at the hole's center increases.And,with a decrease inγorε,the minimum radius of a cavitation bubble at its first collapse increases gradually,the intensity of bubble collapsing slows down,and the time period of the first collapse is prolonged.