克努森数对微尺度相似流动特性影响的实验

为了研究克努森数(Kn)对微尺度相似流动特性的影响,选取理论孔径分别为0.357 4mm的小孔和3.6mm的相似放大孔实验件,并保证相同的长径比.在相同的雷诺数(Re)下对孔的Kn相同和不同的情况进行实验研究,计算孔的流量系数并进行分析比较.结果表明:在相同的Re下,小孔与相似放大孔在Kn相同时,两者流量系数吻合性很好;在Kn不同时,小孔和相似放大孔流量系数不同.因此在采用相似放大模型研究微尺度结构的流动特性时,必须保证相似放大件和微尺度原件Kn相同.

Experiment on effect of Knudsen number on micro-scale similarity flow characteristics

In order to investigate the effect of Knudsen number (Kn) on the micro-scale similarity flow characteristics, a micro-scale hole and another similar scaling-up hole with same length-to-diameter ratio were chosen, with their theroetical hole' diameters of 0.3574mm and 3.6mm, respectively. At the constant Reynolds number (Re), different Kn were chosen to analyze the discharge coefficients of these two holes. Results shows that at the same Re, the discharge coefficients of the two holes are in good agreement with each other while the Kn of these two holes, however, the discharge coefficients don't maintain the same when the Kn are different. As a conclusion, it is necessary to ensure the Kn of the similar scaling-up coupon is the same with the micro-scale coupon when similar scaling-up model is used to investigate micro-scale flow characteristics.