MEMS中气体运动的若干微尺度效应

Some microscale effects of gas flows in MEMS

宏观流动到微流动不单是“量”的变化，而且有“质”的不同。在微流动中，由于微尺度效应，主导流动的作用力发生变化，惯性力不再占主导地位；在宏观尺度流动中可以忽略的表面效应和壁面滑移等现象，开始凸现出来，这就导致了微流动中出现了与宏观流动不同的现象和规律。本文研究微流动问题中的若干微尺度效应：包括微喷管中气体流动的特性、微槽道中的稀薄气体效应和分子泵内的流动问题。这些研究对于设计和开发新的微机械机电设备是非常重要的。

The difference between macroscopic flows and microscopic flows is not only a matter of scale, for these two flows are basically different in nature. In the latter case, the main acting forces are highly perturbed by microscale effects, and inertial forces lose their predominant role. Moreover, surface effects and wall slip that can both be neglected on the macroscale become prominent, leading to the emergence of new phenomena and new governing rules. In this article the influence of several microscale effects are illustrated through the following studies： properties of gas flow in a micro-nozzle, effect of rarefaction in a micro＇ channel gas flow, properties of fluid flows in a molecular pump. These studies are of fundamental importance for the design and development of new Micro Electromechanical System.