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在入口管路束流效应和涡轮端盖反射作用的双重因素影响下,以纯分子流态经泵前入口管道流向涡轮分子泵环形一级动叶列抽气面处的气体分子,其入射密度是不均匀分布的。本文基于自由分子流态基本假设,建立入口直圆管道计算模型,采用试验粒子蒙特卡洛方法,利用Molflow+软件,模拟被抽气体分子经泵入口到涡轮叶列抽气面的飞行过程及行为;数值计算得到气体分子到达涡轮转子一级动叶列入射平面的密度分布和气体通过入口管道的传输几率,并分别经回归分析拟合给出二者的计算公式,可为涡轮分子泵抽气性能的后续研究提供更精确的理论数据;算例证明,以此分布计算分子泵一级动叶列的正向传输几率,比采用均匀分布假设的积分中值法的计算结果偏小。
Under the influence of the inlet pipe beam effect and the turbine end cap reflection, the gas molecules flowing in the pure molecular flow state through the inlet pipe of the pump to the suction surface of the annular first-stage turbine blade of the turbomolecular pump have an incident density of Unevenly distributed. Based on the basic assumption of free molecular flow state, a straight circular pipe model was established. The experimental particle Monte Carlo method and the software Molflow + were used to simulate the flight process and behavior of the extracted gas molecules from the pump inlet to the suction surface of the turbine blade. The density distribution of the gas molecules arriving at the plane of incidence of the first-stage turbine blades and the transmission probability of the gas passing through the inlet pipe are numerically calculated, and the formulas of the two are given respectively by regression analysis and fitting, which can be used to pump the turbopump The follow-up study of the performance provides more accurate theoretical data. The calculation results show that the probability of forward transfer of the first order bucket of the molecular pump is smaller than that of the median value method using the uniform distribution assumption.