Abstract:

Micro particle image velocimetry (Micro-PIV) system was used to study the flow field characteristics of deionized water in micro pin fin arrays with diameter of micro pin fin D=0.4 mm in Reynolds number (Re) range of 50—800. The streamline distribution and velocity field in the staggered and in-line micro pin fin arrays were obtained at different Reynolds numbers. The effects of Re and micro pin fin arrangement on vortex structure and velocity distribution in the wake region were analyzed. The results showed that in the range of Re=50—700, the vortex structure appeared in the staggered and in-line micro pin fin arrays. When Re=800, the vortex shedding began in the staggered micro pin fin array. The vortex length in the wake region of the staggered micro pin fin array increased with the increase of Re. While for the in-line micro pin fin array, the vortex length increased with the increase of Re at low Re, and kept the value of the longitudinal micro pin fin spacing when Re≥300. The streamwise velocity in the main flow area of the in-line micro pin fin array was higher than that of the staggered micro pin fin array. While the transverse velocity in the staggered micro pin fin array was higher than that of the in-line micro pin fin array, and the maximum value was about 25% higher than that of the in-line micro pin fin array. The staggered arrangement of the micro pin fin enhanced the mixing of the fluid in the micro channel.

Key words: micro pin fin array, Micro-PIV, flow field, vortex, streamline, microchannels, microfluidics

摘要：

采用微观粒子图像测速法（Micro-PIV），实验研究了Reynolds数（Re）=50～800范围内去离子水在微肋直径D=0.4 mm微肋阵内的绕流流场特性，获得了不同Re下错排和顺排微肋阵内的流线分布与速度场，分析了Re与微肋排布方式对旋涡结构、流速分布等流场特性的影响规律。研究结果表明，在Re=50～700范围内，错排和顺排微肋阵内均出现涡结构，当Re=800时错排微肋阵内开始发生旋涡脱落；错排微肋阵内旋涡长度随着Re的增大而增加，而对于顺排微肋阵，在低Re时旋涡长度随着Re的增大而增加，当Re≥300后，旋涡长度保持微肋间距不再增加；顺排微肋阵内主流区顺流速度较错排微肋阵大，而错排微肋阵内横向速度大于顺排微肋阵且最大值比顺排微肋阵高约25%，微肋错排布置增强了流体的掺混。

关键词: 微肋阵, 微观粒子图像测速法, 流场, 旋涡, 流线, 微通道, 微流体学