基于维里系数的实际气体分子平均自由程近似计算∗

摘要

When the effect of real gas in the calculation of micro gap gas lubrication is considered,the molecule mean free path of the real gas is required to calculate.A calculation method of the molecule mean free path of the real gas was proposed based on Virial coefficient.According to this calculation method,the compressibility factor in real gas state equa⁃tion was determined by Virial equation,and by substituting the ideal gas state equation with the real gas state equation,the molecule mean free path of the real gas was calculated based on the algorithm of the molecule mean free path of the ideal gas.The molecule mean free paths of the real gas of dry air,CO2,N2,H2 at different pressures were calculated respectively by using this method,and compared with the results of their ideal gas. The results show that the molecule mean free paths of the real gas of dry air are quit close to the calculation results from the idea gas.Under normal pressure,the molecule mean free paths of the real gas of the dry air,CO2 ,N2 are slightly less than those of their ideal gas,and the molecule mean free path of the real gas of H2 is slightly larger than that of the ideal gas.Along the increasing of the pressure,the molecule mean free path is decreased;and the difference of the molecule mean free path between the real gas and the ideal gas is in⁃creased.%考虑微间隙气体润滑计算中的实际气体效应时，需要计算实际气体分子平均自由程。提出一种基于Virial系数的实际气体分子平均自由程的计算方法，该方法通过Virial方程确定实际气体状态方程中的压缩因子，基于理想气体分子平均自由程的算法，用实际气体状态方程代替理想气体状态方程，从而计算得到实际气体分子平均自由程。采用该方法计算不同压力下，空气、 CO2、 N2、 H2实际气体分子平均自由程，并与理想气体分子平均自由程进行比较。结果表明，空气的实际气体分子与理想气体分子的平均自由程计算结果差别很小；常压下，空气、 CO2、 N2实际气体分子平均自由程略小于理想气体， H2的实际气体分子平均自由程略大于理想气体；随着压力增大，分子平均自由程减小，实际气体分子平均自由程偏离理想气体分子平均自由程的程度增加。