微纳米结构壁面对流场及动压润滑的影响研究

Impact of Micro/Nano Surface Structures on Flow Field and Hydrodynamic Lubrication

固体边界具有的微纳米结构将影响流体在近壁面处的流动行为,进而由于尺度效应改变流体在整个微间隙的流动或润滑规律.将壁面可渗透微纳米结构等效为多孔介质薄膜,采用Brinkman方程来描述流体在近壁面边界渗透层内的流动,并将其与自由流动区域的不可压缩流体Navier-Stokes控制方程耦合,在界面处的连续边界条件下求解和分析了速度分布规律和压力变化规律.针对恒定法向承载力的油膜润滑条件,进一步讨论了静止表面或运动表面的微纳米结构对近壁面流动行为的影响;并揭示了考虑壁面微纳米结构的流体动压润滑的油膜厚度和摩擦系数的变化规律.论文结果为具有可渗透微结构表面的微间隙流动与润滑提供了理论参考.

Micro/nano surface structures will affect the fluid flow behavior near the wall in the micro-scale flow, so that the entire fluid flow behavior and lubrication property in micro channel may be changed in which the surface micro/nano structures act as a porous medium layer. Under continuous boundary conditions, the velocity and pressure distribution can be solved using Brinkman equation as the momentum equation of porous region, coupled with Navier-stokes equation which is momentum equation of free region. When assuming the normal load capacity of oil film is constant,permeability characteristics and location of surface micro/nano structures have a great influence on fluid flow behavior near the wall, thus change oil film thickness and friction coefficient of hydrodynamic lubrication. The results provide a theoretical reference of micro-scale flow and lubrication, the surface of which is not completely smooth.