不同极性牛顿流体的微尺度流动  

Flow of Newtonian fluids with different polarity in micro scale

作　　者：吴九柱 程林松[1] 李春兰[1] 曹仁义[1] 陈长超 徐中一[1] 

机构地区：[1]中国石油大学(北京)石油工程学院,北京102249

出　　处：《科学通报》2017年第25期2988-2996,共9页Chinese Science Bulletin

基　　金：国家重点基础研究发展计划(2015CB250902);高等学校博士学科点专项科研基金(20130007120014);国家自然科学基金(51574258;51674273)资助

摘　　要：极性是影响流体微尺度流动的重要因素.本文研究了去离子水(强极性,极性10.2)和异丙醇(中等极性,极性4)在0.04~24.8 MPa/m,半径7.5,5,2.5,1?m微管中的流动规律.结果表明,微尺度下流体流动不再遵循泊肃叶定律,流速偏低,且表现出非线性特征.随着压力梯度升高,边界层厚度不断减小,造成有效流动半径不断增大,导致了流动的非线性.当压力梯度升高到一定程度,边界层厚度稳定,非线性流过渡为线性流.流体极性越强,流固相互作用对流动影响越大,消除黏度影响后,去离子水的边界层厚度大于异丙醇,非线性流动的压力梯度上限低于异丙醇.Due to the great development of medicine,micro-electro mechanical systems（MEMS） and seepage theory of unconventional oil and gas,fluid flow especially liquid flow in micro scale is getting more and more attention.In micro scale,flow is affected by many factors which are negligible in macro scale,thus shows different characteristics compared to conventional theory,such as Navier-Stokes equations.Aiming to study the flow characteristics of deionized water and isopropanol in micro scale,a visual experimental device is established.The direct objective is to measure flow rate of experimental fluids under different pressure gradient,in microtubes with different radius.The pressure is measured directly by pressure transducer.Flow rate is measured indirectly by measuring the displacement of the meniscus in metering tube in a measureable time interval.The tubes are made of fused silica.We choose deionized water and isopropanol as experimental fluids because they both have hydroxide radical.The polarity of water and isopropanol is 10.2 and 4,respectively.The pressure gradient ranges 0.04–24.8 MPa/m.The radius of tubes range 1–7.5 ？m.The length of experimental tubes ranges 8–49 cm.Uncertainty of all experiments is less than 3%.The results showed that fluid flow in microtubes with radius smaller than 7.5 ？m did not conform to Navier-Stokes equations.Experimental flow rate is lower than theoretical value calculated by Poiseuile equation.The flow rate deviation ranges 7.53%–70.75%.Flow rate-pressure gradient curves showed nonlinear characteristics in all experiments.Based on the boundary layer theory of laminar flow,the thickness of boundary layer is calculated.Relationship between boundary layer thickness and its influencing factors is investigated.In this study,thickness of boundary layer is positively correlated with polarity and viscosity,while it is negatively correlated with pressure gradient and radius of the tube.There was a power function relationship between the thickness of boundary layer and pressur

关 键 词：微尺度 微圆管 非线性 分子极性 边界层厚度 

分 类 号：O373[理学—流体力学]