【作者】 刘勇；

【导师】 凌智勇；

【作者基本信息】 江苏大学 ， 机械电子工程， 2006， 硕士

【摘要】 本文采用实验室拥有的微流动实验台，对液体及固液两相流在石英圆管道中压力流动的流量-压力特性进行了实验研究。实验台压力调节范围0～1MPa，用高压气源作为压力源，采用位移法间接测量微管道中的液体流动的流量。本文采用实验介质分别为去离子水和不同质量分数的铜纳米流体。首先，本文测量了去离子水在疏水性和亲水性表面管道中的流动特性，其中微管道内经分别为25μm和50μm，长度分别为40mm和70mm。采用对微圆管道自组装一层单分子octadecyltrichlorosilane(OTS)膜来改变其界面性质，研究了界面性质对去离子水在50μm内径的微管道中流动滑移的影响。实验结果表明去离子水在自组装一层单分子OTS膜管道中的流动，其流量出现明显增大，这是由于去离子水在疏水性微管道中的流动出现了表面滑移。本文不仅研究了单一流体在微管道中的流动情况，而且对纳米流体在微管道中的流动问题也做了一些研究。本文介绍了纳米流体的制备，通过将纳米粒子与去离子水直接混合，采用添加分散剂、超声振动等方法，改变纳米粒子的表面特性，获得悬浮液稳定的纳米流体。采用纳米流体作为实验介质，对其在内经为25μm和50μm，长度为40mm、70mm和100mm的管道中流动的流量-压力特性进行了实验研究，在定常层流条件下，采用宏观的理论对实验流量进行了估算，以便于和实验结果进行比较。实验测量了去离子水—Cu纳米流体在微管道内流动的压力—流量特性，与纯水相比，流量并没有出现明显减小，实验所采用的纳米流体的压力—流量关系符合经典的宏观理论N-S方程，因此，在实验条件下，微管道内纳米流体的流动阻力并未明显增大，且不随纳米粒子的体积份额而变化。更多还原

【Abstract】 Fluid flow through small channels has become a popular research topic due to the emergence of biochemical lab-on-the-chip systems and micro electromechanical system fabrication technologies. But the characteristics of fluid flow in microchannel have not been found. Recently, several researchers have suggested that the well-accepted no-slip boundary condition may not be suitable for flows at the micro/nano scale. First, interface properties of the microchannel wall have been treated, and the interface properties’ effect on the flow slippage character of the deionized water in the microchannel, whose inner radius is 25μm and 50μm, length is 40mm and 70mm, is studied. The interface properties is changed by coating the wall of the capillary with octadecyltrichlorosilane (OTS), and the slip observed by measure the flux and pressure drop of deionized water flow under pressure driven in hydrophilic and hydrophobic microchannel. As the result shown that, when the deionized water flow in the hydrophobic capillary, the flux increased obviously. That because the deionized water slips over hydrophobic surface.In this paper, the characteristics for two-phase fluids flow over microchannel were studied. Preparation of nanofluids is the first key step in experiment. This paper presents a preparation method of nanofluids by directly mixing nanophase powers and base fluids. Some auxiliary dispersants are necessary to obtain the even distributed and suspensions. With this method, several nanofluids with different volume fraction have been prepared. In order to research the problem of two-phase fluids flow over channel, this paper adopt nanofluid as experimental medium, and study the characteristics of the flow rate and pressure driven for nanofluids flow over microchannel, which inner radius is 25μm and 50μm, length rang from 40mm to 100mm. This characteristics of nanofluids compare with the deionized water flow over the same microchannel. The result indicated that the flow rate didn’t monished compared with deionized water, and the flow characteristics of nanofluids in the microchannel in agreement to the macroscopic two-phase liquid flow characteristics. So the flow resistance for nanofluids flow over microchannel don’t increase, and don’t change along with mass fraction.更多还原