Experimental study on visualization of the flow field in microtube |
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Authors: | Liu?Zhigang Email author" target="_blank">Zhao?Yaohua?Email author |
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Affiliation: | Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100080, China |
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Abstract: | An experimental study was conducted to visualize the flow field and confirm the transitional Reynolds number from laminar
to turbulent flow, as distilled water flows through quartz glass microtubes with inner diameter 315 and 520 μm. With gentian
violet as colorant, the flow field pictures in the microtube, and therefore, is shot by a CCD camera with a microscope at
different Reynolds numbers. Pressure drop data were also used to characterize the friction factor for those microtubes in
the Reynolds number range of 200–2300. The experimental results clearly showed that the flow in the microtube was the laminar
state and the friction factors agreed well with the Poiseuille equations when the Reynolds number was low. As the Reynolds
number was larger than 1200 and 1500 for the microtube with inner diameter 315 and 520 μm, respectively, the friction factor
departed from the classical laminar solution due to the earlier transition from laminar to tubulent flow. The flow turned
into full turbulent when the Reynolds number reached 1500–1800. |
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Keywords: | visual experiment microtube microscale flow friction factor turbulent transition |
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