克努森数在微尺度相似流动特性研究中的作用

为了研究克努森数对微尺度相似流动的影响,选取孔径分别为3,1,0.5,0.3mm的相似小孔模型并视流体为连续介质,在相同的雷诺数下对各尺度小孔流体克努森数不同和相同的情况进行数值模拟,计算小孔的质量流量系数并分析其内部流场特征.结果表明:在相同的雷诺数下,原件与放大件的内部流场在克努森数相同时表现出更好的相似性,小孔质量流量系数也表现出更好的吻合性,因此在采用相似放大模型研究微小尺度结构的流动特性时,为了得到更为准确的结果,必须保证相似放大件和微尺度原件克努森数相同.

Effect of Knudsen number on microscale similar flow characteristics

Four similar hole models with the aperture of 3,1,0.5 and 0.3mm were selected,with the fluid regarded as continuous medium to investigate the effect of Knudsen number on the characteristics of microscale similar flow.The mass flow rate coefficient was calculated by numerical simulation when the Knudsen number of fluid with each scale pore was variable and constant at the same Reynolds number,and then the internal flow field was analyzed.The results show that when the Knudsen numbers of the four hole models are equal,the internal flow fields and the mass flow rate coefficients of different scale pores show a better similarity at the same Reynolds number,so it is required to ensure the same Knudsen number to get more accurate results in investigating the flow characteristics of microscale structure by amplificatory models.