液体中空泡收缩过程的数值研究

Numerical Study on the Collapse of Cavitation Bubbles in Liquids

材料在液体中的空蚀破坏程度会因为液体环境的改变而大相径庭,而液体中空泡的生长、溃灭是造成材料空蚀破坏最根本的原因。为了研究液体环境对空泡运动过程的影响,利用有限差分法计算空泡在不同液体环境中的收缩过程,对不同液体黏性、表面张力条件下不同尺寸空泡的收缩过程进行了分析。计算结果表明:液体黏性会减缓空泡收缩过程中的脉动现象,且黏性越大,空泡收缩过程中脉动现象所持续的时间越短,脉动幅度也越小;表面张力越大,空泡收缩稳定后的半径也越大,且表面张力在空泡收缩过程中表现出的对空泡泡壁的加速效应会增大空泡的脉动频率。与前人的研究相比,研究还发现:在同样的液体环境中,随着空泡初始半径的减小,空泡在收缩过程中呈现出的脉动现象所持续的时间会越来越短,而最终稳定后的量纲一半径则会越来越大,即空泡在收缩过程中被压缩的比例越来越小。计算结果为理解液体中空泡的溃灭行为和由此引起的空蚀破坏提供了理论依据。

Cavitation erosion of materials can be different when the liquid is changing. As the dynamics of cavitation bubbles directly lead to the cavitation erosion of materials, it is necessary to investigate the bubble dynamics in different liquids. The collapse process of bubbles filled with gases and vapors in liquid was numerically studied. The influence of viscosity and surface tension on the Collapse was investigated. It was found that the pulsing phenomenon during the collapse process is affected mostly by the viscosity ,while the final radius of the bubbles mostly by the surface tension. The time that the pulsing phenomenon lasts and the pulse amplitude appear to decrease with the increase of the viscosity, yet the frequen- cy of the pulsing phenomenon and the final radius Of the bubbles increase with the increase of the surface tension for the acceleration effect brought by the surface tension to the bubble wall. A smaller initial bubble radius would lead to a shorter pulsing phenomenon and a bigger final non-dimensional radius than a larger one, which was not found in former researches. This research can lead to a better understand of the collapse of cavitation bubbles, which can induce the cavitation erosion of materials.