Zhang Zhijun, Wang Xiaowei, Zhao Lili, Zhang Shiwei, Zhao Fan
School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819, China.
School of Mechanical Engineering, Shenyang University, Shenyang 110044, China.
Micromachines (Basel). 2019 Jan 24;10(2):79. doi: 10.3390/mi10020079.
A Knudsen pump operates under the thermal transpiration effect or the thermal edge effect on the micro-scale. Due to the uneven temperature distribution of the walls in the channel axis direction or the constant temperature of the tips on the walls, directional thermally-induced flow is generated. In this paper the Direct Simulation Monte Carlo (DSMC) method is applied for N₂⁻O₂ gas mixtures in the ratios of 4:1, 1:1, and 1:4 with different Knudsen numbers in a classic rectangular Knudsen pump to study the flow characteristics of the gas mixtures in the pump. The results show that the changing in the gas physical properties does not affect the distribution of the velocity field, temperature fields, or other fields in the Knudsen pump. The thermal creep effect is related to the molecular mass of the gas. Even in N₂ and O₂ gas mixtures with similar molecular masses, N₂ can be also found to have a stronger thermal creep effect. Moreover, the lighter molecular weight gas (N₂) can effectively promote the motion of the heavier gas (O₂).
克努森泵在微观尺度下基于热渗透效应或热边缘效应运行。由于通道轴向壁面温度分布不均匀或壁面尖端温度恒定，会产生定向热致流。本文将直接模拟蒙特卡洛（DSMC）方法应用于经典矩形克努森泵中，研究比例为4:1、1:1和1:4且具有不同克努森数的N₂ - O₂混合气体，以探究泵内混合气体的流动特性。结果表明，气体物理性质的变化不会影响克努森泵内速度场、温度场或其他场的分布。热蠕变效应与气体的分子量有关。即使在分子量相似的N₂和O₂混合气体中，也能发现N₂具有更强的热蠕变效应。此外，较轻分子量的气体（N₂）能有效促进较重气体（O₂）的运动。
