摘要：It is very important to analyze and study the motion process of droplets impacting superhydrophobic surface, which is of great significanee to understand the mechanism of superhydrophobic surface and guide the design and manufacture of superhydrophobic surface. Taking by three-dimensional volume of fluid (VOF) simulation coupling coupled level set (CLS) algorithm, on the one hand, we simulate the morphological changes in the process of droplet impingement, as well as the internal velocity and the pressure distribution;on the other hand,we focus on the effects of droplet impact velocity, surface wettability, surface tension on the dynamics of the droplets. The CLSVOF model inherits the advantages of the VOF model for accurately constructing the phase interface and inherits the advantage that the level set can accurately calculate the surface tension, which improves the accuracy of the calculation of the droplet impact on the superhydrophobic surface. The computed results distinctly demonstrated there were four stages: falling, spreading, shrinking and rebounding. The time history of each stage agreed well with the pictures captured by high-speed camera, which indicated the computational fluid dynamics scheme was effective. Moreover, the motion mechanism of the droplets impacting on the solid surface is elaborated, which was helpful to control the solid-liquid interface to achieve a variety of solid interface characteristics.

摘要：目的:船用螺旋桨性能评估中常用的雷诺平均方法(RANS)存在许多难题,特别是在处理边界层发展、尺度效应、翼尖和轮毂涡等复杂流动现象时。本文使用动态大涡模拟(DLES)、延迟分离涡模拟(DDES)和应力混合涡模拟(SBES)三种尺度解析模拟(SRS)方法,以提高流动特性预测的准确性。创新点:1.通过SRS方法详细地描述螺旋桨流场的不规则和多尺度湍流结构;2.通过粒子图像测速(PIV)试验,分析缩比螺旋桨的真实流场。方法:1.考虑叶片的周期分布和计算消耗,提取1/5的螺旋桨计算区域,并采用局部网格细化方法,获得分辨率足够高的网格模型(图1);通过仿真结果与已有试验数据的对比,验证SRS方法在螺旋桨性能预测方面的可行性与有效性(图3)。2.通过搭建PIV试验装置(图4),得到缩比螺旋桨在特定横截面上的速度和涡量分布情况下的尾流演变(图9和10),从而分析SRS方法对流场结构的捕捉能力。结论:1.通过定量和定性分析发现,SRS方法在预测特征参数和捕捉流场信息方面表现良好,特别是值得重点关注的SBES模型;2.作为一种可视化流场分析工具,PIV测量方法可以为螺旋桨等旋转机械的设计和性能改进提供一定的参考依据。