Analysis of velocity slip flow in lubrication film of aerostatic guide way in micron scale

摘要

When lubricating gas film of aerostatic guide way worked in the level of micron, rarefaction effect plays an important role in internal airflow. Based on simulation of large-scale molecular massively parallel simulator (LAMMPS), Lattice Boltzmann method (LBM) and computational fluid dynamics (CFD) in this paper, velocity slip and pressure distribution in gas film are discussed. In the method of calculation and simulation, the gas film lubrication along flowing direction can be classified into two areas: pressure driven area and Newton friction area. But, at the same time, along its height direction, it is also divided into near wall layer, rarefied layer and continuous flow layer. Velocity slip mainly appears in both the near wall layer and the rarefied layer of pressure driven area. Meanwhile, velocity slip present in pressure driven area and Newton friction areas. Gas stratification and velocity slip maybe enhanced with increasing gas flow rate, whereas gas stratification in Newton friction zone is gradually weakening. Therefore, slippage speed gradually degenerates into the level of near-wall boundary layer.