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首页> 外文期刊>Experimental Thermal and Fluid Science: International Journal of Experimental Heat Transfer, Thermodynamics, and Fluid Mechanics >Turbulent and transitional velocity measurements in a rectangular microchannel using microscopic particle image velocimetry
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Turbulent and transitional velocity measurements in a rectangular microchannel using microscopic particle image velocimetry

机译：使用显微粒子图像测速仪测量矩形微通道中的湍流和过渡速度

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Microscopic particle image velocimetry (microPIV) experiments were performed on a polydimethylsiloxane (PDMS) microchannel with a cross-section measuring 320 mum x 330 mum for Reynolds numbers between 272 and 2853. Care was taken to ensure that the seed particle density was great enough that accurate instantaneous velocity vector fields could be obtained for all the Reynolds numbers investigated. Velocity fluctuations were calculated from ensembles of microPIV velocity fields. The /u(max) fluctuation showed an increase at Re = 1535 and a further increase as Reynolds numbers were increased, suggesting that transition to turbulence began near Re = 1535, a Reynolds number lower than predicted by classical theory. The /u(max) data also suggest the flow was fully developed at a Reynolds number between 2630 and 2853, also lower than classical results. This finding was confirmed in plots of the mean velocity profile. For the fully developed flow, the measured /u(max) fluctuation agreed well with classical results for turbulent duct flow, but the /u(max) fluctuation was 25-40% lower than turbulent duct flow results. Finally, spatial correlations of velocity fluctuations were calculated to lend some insights into the characteristics of the large-scale turbulent structures observed in the turbulent microchannel flow. (C) 2004 Elsevier Inc. All rights reserved.
机译：显微颗粒图像测速（microPIV）实验是在聚二甲基硅氧烷（PDMS）微通道上进行的，横截面尺寸为320微米x 330微米，雷诺数在272和2853之间。要注意确保种子颗粒密度足够大对于所研究的所有雷诺数，都可以获得准确的瞬时速度矢量场。从microPIV速度场的集合计算速度波动。 / u（max）波动与湍流管道流量的经典结果非常吻合，但 / u（max）波动比湍流管道流量低25-40％结果。最后，计算了速度涨落的空间相关性，以便对湍流微通道流中观测到的大规模湍流结构的特征有所了解。 （C）2004 Elsevier Inc.保留所有权利。

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