The gas flow diode effect: theoretical and experimental analysis of moderately rarefied gas flows through a microchannel with varying cross section
The gas flow diode effect: theoretical and experimental analysis of moderately rarefied gas flows through a microchannel with varying cross section
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气流二极管效应：中等稀薄气流通过不同横截面微通道的理论和实验分析
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
J. Thöming
中科院分区：
文献类型：
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作者：
I. Graur;T. Veltzke;J. Méolans;M. Ho;J. Thöming
摘要
适度稀薄的气体流动在连续区域中与粘性流动和在高稀薄度下与自由分子流动清楚地区分开。作为相关的各种技术应用，这种流动过程的理解是至关重要的微机电系统（MEMS）和真空技术的相当大的增强。在这项工作中，我们专注于稀薄气体通过纵向变化截面的长通道的等温流动。我们采用两种方法，一个分析和一个数值的线性化的S-模型的解决方案的基础上，都允许我们预测的质量流率在发散和收敛的流动方向为任意压力梯度。这两种方法都验证了CO2，N2和Ar渗透实验的锥形微通道制造的微铣削。当地的克努森数范围从0.0471到0.2263。所有的数值和分析结果与实验数据吻合良好，并表明，当管道灌注收敛方向的质量流量显着较高。对这种气流二极管效应的物理现象的理解可能为MEMS中的新型组件（如静态单向阀）铺平道路。
Abstract
Moderately rarefied gas flows are clearly distinguished from viscous flow in the continuum regime and from free molecular flow at high rarefaction. Being of relevance for various technical applications, the understanding of such flow processes is crucial for considerable enhancement in micro electromechanical systems (MEMS) and vacuum techniques. In this work, we focus on the isothermal rarefied gas flow through long channels with longitudinally varying cross section. We apply two approaches, an analytical one and a numerical one that is based on the solution of the linearized S-model, both allowing us to predict the mass flow rate in diverging and converging flow directions for arbitrary pressure gradients. Both approaches are validated by CO2, N2 and Ar permeation experiments on tapered microchannels manufactured by means of micromilling. The local Knudsen numbers ranged from 0.0471 to 0.2263. All the numerical and analytical results are in good agreement to the experimental data and show that the mass flow rate is significantly higher when the duct is perfused in converging direction. The understanding of the physical phenomenon of this gas flow diode effect might pave the way for novel components in MEMS such as static one-way valves.