科研之友
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摘要
The experiments of microflow are very difficult to handle, owing to a few factors influencing the measurement accuracy. Based on our experiences, a detailed introduction about the experimental uncertainty and the relative factors is presented in this paper. From the analysis of the experimental uncertainty, the measurement of microtube diameters obviously dominates the experimental precision. Several factors, for example, the evaporation on gas/liquid interfaces, the deformation of microtube, the compressibility of liquid, the viscous heating and the wall slip are discussed. According to our present experimental results, the flow characteristics driven by the lower pressure in microtubes with the diameter larger than 20 mum agree well with the prediction from classical Hagen-Poiseuille (H-P) theory, while the viscosity vs. pressure relationship should be considered under a high pressures in the microtubes with 3-10 mu diameters, and the precision depiction of shape is taken into account in the cone-shape microneedle with the outlet diameter 1-15 mum.
