基于Micro-PIV的不同截面形状微柱群内部流场特性研究

采用显微粒子测速技术（Micro-PIV）对圆形、椭圆形及菱形等不同截面形状错排微柱群绕流流动进行研究，得到了不同雷诺数（Re）下微柱群内部的速度场、流线等绕流流场信息，分析了Re与截面形状对绕流流场结构的影响规律。研究结果表明，微柱体绕流过程中漩涡脱落相对于常规尺度具有一定的滞后性；圆形微柱体背风区最早发生流动分离，菱形、椭圆形次之；随着Re的增大，微柱体尾流区出现涡结构，回流长度逐渐增大，在三种截面形状微柱群绕流流动中圆形截面微柱群的回流长度和回流区域最大。

Study on flow field in micro-cylinder groups with different cross-section shapes by Micro-PIV method

The flow around staggered micro-cylinders with different cross-sectional shapes, such as circular, elliptical, and diamond, was investigated via micro particle image velocimetry (Micro-PIV). Flow field information, such as velocity field and streamline, was obtained using different Reynolds numbers（Re）, and the impacts of Re and cross-sectional shape on the flow field structure were analyzed. Results show that boundary layer separation in the process of flow around the micro-cylinder lagged in comparison to macro-scale flow around the cylinder. Flow separation in the wake region of the micro-cylinder having a circular cross-section occurred earlier than those of micro-cylinders having elliptical and diamond-shaped cross-sections. A vortex structure appeared in the wake region of the micro-cylinders, and backflow length increased with the increasing Re. The backflow length and backflow area of the flow around the micro-cylinder having a circular cross-section are the largest among the three types of cross-sections.