瞬变流中气泡动力过程研究

微气泡的生成等基础问题制约着鼓泡脱气技术的发展。本文基于对文丘里鼓泡器内流场的研究,对不同雷诺数下的气泡动力特性进行研究,采用大涡模拟和流体体积法相结合的数值模拟方法,对气泡在不同瞬时动态变化流场下的动力特性进行研究,通过分析气泡在不同湍流下的表面积,气泡球度,以及气泡表面所处的湍流应力,计算气泡所受的破坏应力与聚合应力之比,得到气泡的临界韦伯数随气泡在瞬变湍流中的变化过程,分析气泡破碎的临界条件。

Study of the Bubble Dynamics in the Unsteady Flow

Problems such as the generation of microbubbles restrict the development of bubble degassing technology.In this paper,based on the study of the flow field in the Venturi bubble generator,the dynamic characteristics of the bubble under different Reynolds numbers are studied.The numerical simulation method combined with the large eddy simulation(LES)and the fluid volume method(VOF)is used to analyze the bubble dynamics under different unsteady transient flow fields.The dynamic characteristics are studied by analyzing the surface area of the bubble under different turbulences,the bubble sphericity,and the turbulent stress on the bubble.It indicates that the variation of Weber number of the bubble is obtained by the ratio of the destructive stress suffered by the bubble and the cohesive stress on the gas-liquid interface.In the process of transient turbulence,the bubble breakup is concerned with the Weber number reaching a critical value.