超重力下气泡聚并破碎特性的数值分析

Numerical Analysis of Bubble Coalescence and Breakup Characteristics under High Gravity

摘要: 气泡广泛存在于自然界及工业生产中，气泡的聚并破碎现象对气液两相流动及传热传质行为有重要的影响，研究气泡在超重力场下的聚并破碎现象对工业生产具有重要的意义。计算流体力学(Computational Fluid Dynamics, CFD)与群平衡模型(Population Balance Model, PBM)耦合能有效地模拟气液两相流动，且可以对气泡的聚并与破碎行为进行模拟。通过用户自定义函数(User Defined Functions, UDF)在径向上添加恒定力场，运用CFD-PBM耦合模型对超重力场中的气液两相流进行了模拟研究，探究超重力场对气泡运动行为及聚并破碎特性的影响，并对超重力场中气泡的聚并破碎机理进行探究。研究表明，超重力场对气泡的聚并破碎有着显著的影响，当超重力场强度较小时其主要影响气泡的聚并，大气泡含量较多，气泡尺寸分布较窄；随着超重力场强度的增加，气泡的破碎行为逐渐增强，小气泡的含量显著增多，气泡的尺寸分布变宽。

Abstract: Bubbles exist widely in nature and in industrial production. The coalescence and breakup of bubbles have an important effect on gas-liquid two-phase flow and heat and mass transfer behavior. It is of great significance to study the coalescence and breakup of bubbles under different force fields for industrial production. The CFD-PBM model can effectively simulate the gas-liquid two-phase flow and simulate the coalescence and breakup behavior of bubbles. A constant force field was added to the radial direction of the User Defined Function (UDF), and the gas-liquid two-phase flow in the high gravity field was simulated by using the CFD-PBM coupling model. The effects of the high gravity field on bubble motion and coalescence-breakup characteristics were investigated, and the coalescence-breakup mechanism of bubbles in the high gravity field was also investigated. The results show that the high gravity field has a significant effect on the coalescence of bubbles. When the intensity of high gravity field is small, it mainly affects the coalescence of bubbles, and there are more large bubbles and the size distribution of bubbles is narrow. With the increase of the strength of high gravity field, the bubble breakup behavior gradually increases, the content of small bubbles increases significantly, and the size distribution of bubbles becomes wider.