Untersuchungen zu laminarer, transitioneller und turbulenter Strömung in rechteckigen Mikrokanälen
Untersuchungen zu laminarer, transitioneller und turbulenter Strömung in rechteckigen Mikrokanälen
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Untersuchungen zu laminarer、transitioneller 和 turbulenter Strömung in rechteckigen Mikrokanälen
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发表时间：
2009
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通讯作者：
Wolf Wibel
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作者：
Wolf Wibel
对微通道内压降和层流-湍流转捩的研究结果存在争议。为此，本文对矩形微通道内的压降进行了实验研究。根据计算结果，计算了压降关联式，并通过入口和出口效应进行了校正。利用μ PIV技术在通道内进行速度测量。在这里，通过时间平均的速度分布和湍流波动，过渡到湍流内部的微通道的特征。这种调查发生在不同的通道的末端。在沿通道沿着流入区内部的不同位置，以恒定的雷诺数进行额外的研究。实验中使用的微通道被研磨成不锈钢;它们的水力直径均匀地为d h = 133 μm。为了研究纵横比对压降和过渡的影响，研究了纵横比a = 1，2，5的通道。单通道还通过喷砂进行粗糙化，以研究表面粗糙度的影响。的比较和讨论的结果在宏观通道中的类似调查进行。
Investigations in literature show controversial results for the pressure drop and the laminar-turbulent transition in microchannels. Experimental investigations on the pressure drop in rectangular microchannels are undertaken in this work for this reason. From the results pressure drop correlations are calculated, corrected by inlet and outlet effects. Velocity measurements utilizing μPIV-technique are performed inside of the channels. Here, both by time-averaged velocity profiles and by turbulent fluctuations, the transition to turbulent flow inside of the microchannels is characterized. This investigation takes place at the end of the channels at varying Reynolds-numbers. Additional investigations are performed at constant Reynolds-number at different positions inside of the inflow zone along the channel. The microchannels utilized within the experiments are milled into stainless steel; their hydraulic diameter is uniformly d h = 133 μm. To investigate the influence of the aspect ratio on the pressure drop and the transition, channels of aspect ratios a = 1, 2, 5 are investigated. Single channels are additionally roughened by sandblasting to investigate the influence of surface roughness. A comparison and discussion of the results in reference to analogous investigations in macroscopic channels is performed.