湍动流场中粘弹液滴变形破碎的三维数值模拟及实验研究

The deformation and fragmentation of viscoelastic droplets not only exist commonly in nature but also involve a large number of key technologies in industry. The study on the breakup of viscoelastic droplets is paucity. This project will combine the experimental method and numerical simulation approach to investigate the oscillating breakup of viscoelastic droplet in turbulence flow. It will focus on the following three aspects: 1. Based on the constitutive equations of viscoelastic liquid, the three dimensional numerical model on the pneumatic breakup of viscoelastic droplets will be established, which include the large eddy simulation, the coupled level set and volume of fluid method, as well as high order encrypted adaptive mesh. Results will reveal the mechanism of rheological effect coupled with turbulence pulsation related to the breakup and deformation of droplets. 2. Based on abundant experiments and calculated results, the dimensionless numbers which apply to the breakup of viscoelastic droplets will be proposed to define its breakup modes and critical values. 3. The harmonic oscillation breakup model will be established for the numerical calculation of numerous droplets in the Euler -Lagrange frame. It can be used to predict the distribution of the fragments.

粘弹液滴的变形破碎不仅在自然界中普遍存在而且还涉及工业界的大量关键技术，目前对此的研究非常缺乏。本项目拟采用数值计算和实验测量方法对湍动流场液滴振荡破碎进行研究，重点完成如下三方面工作：1.基于粘弹流体本构方程，采用湍流大涡模拟，耦合的水平集-流体体积界面捕捉方法和高阶加密自适应网格，建立粘弹液滴气动破碎的三维数值模型，揭示流变效应耦合湍流脉动对液滴变形破碎的作用机理。2.基于大量实验和计算结果，提出适用于粘弹液滴破碎的无量纲参数集，界定其破碎模态和临界值。3.建立适用于欧拉-拉格朗日框架下大量液滴群数值计算的粘弹流体液滴谐波振荡模型，并预测子液滴的分布规律。

本项目采用数值计算,实验测量和理论分析对湍动流场液滴变形破碎进行系列研究，主要包括：1、基于粘弹流体本构方程，采用湍流大涡模拟，耦合水平集-流体体积界面捕捉方法和高阶加密自适应网格，建立液滴变形破碎的三维数值模型，涉及的液滴物性包括牛顿流体、剪切变稀的非牛顿流体，粘弹流体等。2、基于大量实验和计算，结合不稳定性理论，受力平衡分析，谐波振荡模型和能量守恒原理，提出适用于粘弹液滴破碎的无量纲参数集，分析关键无量纲参数的变化趋势，界定其破碎模态和临界值，预测和分析破碎后子液滴的分布规律。3、对高韦伯数下液滴的对心/非对心，等径/非等径碰撞问题进行数值模拟和实验测量研究，分析碰撞参数对液滴碰撞破碎结果的影响，并对碰撞聚结过程中的形变程度、能量演变和压力流场进行研究。4、对液滴撞击固体壁面的动力学特性开展研究，主要关注液滴撞击曲面，微结构表面，移动表面和非对称情况的模态划分，铺展和反弹特性。项目负责人以一作或通讯发表（含录用）SCI论文14篇，中文论文1篇；发明专利授权1项，实审10项。参加全国会议6次，国际会议6次，特邀报告4次，培养研究生9名，入选省部级人才两人次。项目经费开支均在预算之内，直接经费执行率87.55%。