表面特性对棘齿型Knudsen泵气体分离特性影响的模拟研究  

Simulation Study of the Effect of Surface Properties on Gas Separation Characteristics for Ratchet-type Knudsen Pumps

作　　者：韩峰 张志军[1] 张世伟[1] 王晓伟 HAN Feng;ZHANG Zhi-jun;ZHANG Shi-wei;WANG Xiao-wei(School of Mechanical Engineering and Automation,Northeastern University,Shenyang 110819,China)

机构地区：[1]东北大学机械工程与自动化学院,辽宁沈阳110819

出　　处：《真空》2024年第3期13-19,共7页Vacuum

基　　金：国家自然科学基金资助项目(U20A20292);中国航空工业空气动力研究院高超声速气动力与热技术重点实验室基金资助;北京控制工程研究所先进空间推进技术实验室和北京市高效能及绿色宇航推进工程技术研究中心开放基金项目(LabASP-2020-02);中国科学院环境光学与技术重点实验室开放基金(2005DP173065-2022-02)。

摘　　要：Knudsen泵作为一种微型泵,在微机电系统(MEMS)中具有广泛应用。本文提出了一种具有不同表面反射系数的棘齿型Knudsen泵,通过直接模拟蒙特卡罗(DSMC)方法对该泵内He-Xe混合气体流动特性进行了数值模拟研究。结果表明:表面反射特性对Knudsen泵内的流场特性和气体分离特性影响巨大,不同的表面反射特性导致了Knudsen泵内不同的热驱流动机理;三角形倾斜边的α_(n)=σ_(t)=0时Knudsen泵内主要热驱流动为辐射流,有利于气体分离,而α_(n)=σ_(t)=1时Knudsen泵内主要热驱流动为热边缘流,对气体分离没有明显有利作用;三角形倾斜边的α_(n)=σ_(t)=0时He和Xe的速度和扩散速度在三角形棘齿上顶点附近差异最大,而α_(n)=σ_(t)=1时在三角形棘齿左侧顶点附近差异最大;越轻的气体流动速度和扩散速度越快。本文可为实际工程应用中微型气体分离装置的设计和生产提供理论依据。The Knudsen pump,a type of micro-pump,is widely used in microelectromechanical systems(MEMS).The paper proposes a ratchet-type Knudsen pump with varied surface accommodation coefficients.The gas flow characteristics of this pump are simulated numerically by using the direct simulation Monte Carlo(DSMC)method.The results show that surface accommodation characteristics significantly influence the flow field and gas separation features.Distinct surface reflection characteristics give rise to varying thermally induced flow mechanisms within the Knudsen pump.The primary thermally induced flow in the Knudsen pump atα_(n)=σ_(t)=0 of the inclined edge of the triangle is the radiometric flow,which is advantageous for gas separation.Atα_(n)=σ_(t)=1 of the triangular inclined edge,the primary thermally induced flow is the thermal edge flow,which is not clearly advantageous for gas separation.The velocity difference and diffusion velocity difference between He and Xe are greatest near the upper vertex of triangular ratchet atα_(n)=σ_(t)=0 of the triangular inclined edge,while the differences are greatest near the left vertex of triangular ratchet atα_(n)=σ_(t)=1.Moreover,the flow velocity and diffusive velocity increase as the gas becomes lighter.This paper may establish a theoretical foundation for creating and producing miniature gas separation devices applicable in practical engineering contexts.

关 键 词：Knudsen泵 气体分离 表面特性 热驱流动 棘齿型微通道 DSMC方法 微机电系统(MEMS) 

分 类 号：TB711[一般工业技术—真空技术] O356[理学—流体力学]