微通道气体单相流动特性的数值分析

Numerical analysis of single-phase gaseous flow characteristics in microchannels

微通道是各种微系统结构中一个基本的组成部分.考虑了可压缩与粘性加热的影响,针对氮气在3种不同尺寸的微通道(水力直径范围:30～3 000μm)内的流动特性进行了数值研究.分别就不同尺寸、不同雷诺数(Re)下压力降、摩擦因子和摩擦常数的规律进行了研究,着重考察了长径比、入口段出口段影响、可压缩性影响及粘性加热影响.计算分析揭示出转捩雷诺数提前,在300μm管道转捩雷诺数提前到1 200附近.

The microchannel is an integral part of various micro systems. The flow characteristics of nitrogen in three different microchannels （hydraulic diameter of 30-3 000 μm） were numerically investigated with consideration of the effect of compressibility and viscosity heating. The effects of size and Reynolds number （Re） on pressure drop, friction factor and friction constant were investigated. Especially, the priority of the research was placed on the effect of ratio of length, entrance/exit, compressibility and viscosity heating. The calculated results show that transition Re is brought forward to about 1 200 in 300 μm microchannels.