稀薄条件下平板间润滑气膜内速度滑移现象分析  

ANALYSIS OF VELOCITY SLIP BETWEEN FLAT IN LUBRICATING FILM UNDER CONDITIONS OF THIN GAS

作　　者：宁方伟[1] 龙威[1] 公玲[1] 裴浩[1] 杨绍华[1] 

机构地区：[1]昆明理工大学机电工程学院,昆明650500

出　　处：《机械强度》2016年第4期738-743,共6页Journal of Mechanical Strength

基　　金：国家自然科学基金项目(51305185)资助~~

摘　　要：空气静压导轨润滑气膜工作在微米级时,内部气流受稀薄效应影响,沿流动方向压力和流速的变化规律与宏观计算所得差异较大。在气膜高度方向上,由于特征尺度减小,气体分子间作用效果加剧,传统忽略垂直方向压力梯度变化的假设不再成立,气膜内部不仅呈现较明显的分层趋势,并且速度滑移现象越发显著。通过LAMMPS(大规模原子分子并行模拟器)、LBM(离散格子玻尔兹曼方法)和Fluent等方法模拟气膜支撑区气体流态并计算其流速和压力,得出了相关结论:润滑气膜内沿气体流动方向分为压力驱动区和牛顿摩擦区,沿高度方向分为近壁层、稀薄层、连续流层,速度滑移主要发生在压力驱动区的近壁层和稀薄层。气膜分层及速度滑移现象存在于压力驱动区和牛顿摩擦区;压力驱动区的气膜分层及速度滑移随气体流速的增加而增强,牛顿摩擦区的气膜分层逐渐弱化,速度滑移现象逐渐退化为近壁面边界层。When lubricating gas film of aerostatic guide way worked in micron level,internal airflow was affected by rarefied gas,the pressure and flow rate along flow direction was different to the result of calculating. In the gas film height direction,due to the characteristic scale decreased,the effect of gas molecule was intensified,traditional assumption of ignored vertical pressure gradient no longer founded,not only interior air film present obvious stratified trend,but velocity slip phenomenon was more significant. Simulating flow patterns and calculating its velocity and pressure in gas film by LAMMPS（ Large-scale Molecular Massively Parallel Simulator）,LBM（ Lattice Boltzmann Method） and Fluent in this paper,came to the relevant conclusion： the gas film in the longitudinal direction was divided into pressure-driven area and Newton friction area,and it also was divided into near wall layer,thin layer,continuous flow layer along its height direction,velocity slip mainly occurred in the near wall layer and thin layer of pressure-driven area. Gas stratification and velocity slip present in pressure-driven and Newton friction areas;Gas Stratification and velocity slip was enhanced with increasing gas flow rate,gas film stratification in Newton friction zone was gradually weakening,slippage speed gradually degenerated into near-wall boundary layer.

关 键 词：稀薄效应 速度滑移 Knudsen数 分子碰撞 牛顿摩擦 

分 类 号：TH47[机械工程—机械制造及自动化]