摘要
长直圆管道内气体流动问题是真空抽气理论研究中最基本的问题,也是研究最多,理论最成熟的一部分内容。但是在一些特殊的应用场合中流动控制的细节上还存在一些问题有待于解决。本文研究了长直圆管道快速抽真空问题和分子流态下长直圆管道出口处分子的分布规律问题。
在研究真空搬运机械手快速响应的过程中,本文建立了真空机械手快速响应时间的数学模型,并对数学模型进行求解。在求解其中真空度响应时间的过程中发现,数学模型不能求解。为了解决这个问题本文采用了Fluent模拟的方法,但是模拟过程中发现Fluent软件没有合适的边界条件,于是本文采用了UDF编程的方法解决非稳态流动速度的边界条件问题。利用模拟结果对模型进行优化,结果表明优化后的结构能够满足工程的需要。把Fluent软件引入到真空抽气模拟过程中,这不仅可以指导实际应用还为流体计算软件在真空模拟方面的应用和软件自身算法改进提供了新思路。利用Fluent软件进行真空抽气过程的模拟,可以直观的体现抽气过程的各种参数变化,在新产品开发过程中可以部分代替实物试验,减少试验风险,降低生产成本。
目前对于分子流下分子穿过直圆管道后的分布规律问题研究还不完善,本文总结前人研究的成果进一步完善了分子流态下长直圆管道出口处分子分布规律理论。本文建立了直圆管道中分子第一次飞行的数学模型并进行求解。由于数学模型不能够完全表达分子的运动规律,所以用蒙特卡洛法编程解决数学模型没有解决的问题。程序计算结果与第一次飞行分子的数学模型计算结果吻合,说明程序是正确可信的。程序对穿过长直圆管道的气体分子进行分类讨论,比较了直接穿过长直圆管道的分子和碰撞后间接穿过长直圆管道的分子对整体束流效应的贡献程度。本文还提出了“角度束流效应评价参数”概念,完善了束流效应评价参数理论。数学模型计算结果和蒙特卡洛法模拟结果表明经典的束流效应理论模型存在误差。
The gas flow problem in the long straight cylindrical pipeline is the most fundamental problem in the study of the vacuum pumping theory. However in some special application situations, there are some questions in the details on flow control which remain to be resolved. This paper investigates the rapid vacuum pumping problems in the long straight cylindrical pipeline and the molecules distribution problems of molecular flow in the long straight cylindrical pipeline.
On the study of the process of vacuum transportation manipulator rapid response, this paper established the mathematical model of the vacuum transportation manipulator rapid response time. On the process of solving the vacuum rapid response time, we found that the mathematical modal can not be solved. To resolve this problem, this paper adopted Fluent simulation method. But in the process of the simulation, we found that the fluent software did not have the suitable boundary conditions, so this paper used the UDF programming method to solve this non-steady flow rate boundary conditions problem. By using this simulation results to optimize the mathematical model, the results show that the optimized structure can meet the engineering needs. By applying the Fluent software to the process of vacuum pumping simulation, not only can guide practical application but also can offer new ideas of the application of vacuum simulation and the improvement of the software its own algorithm. By using the fluent software to simulate the vacuum pumping process, all kinds of the parameters changes of the pumping process can be displaied directly. In the process of new product development, this simulation can partly replace practicality experiment, reduce experimental risks, and decrease production costs.
At present the study of the the molecules distribution problems of molecular flow in the long straight cylindrical pipeline is not perfect. This paper summarized the previous research results and further perfect the molecular distribution theory of molecular flow at the outlet of the long straight cylindrical pipeline. This paper established the molecule first flight mathematical model in the straight cylindrical pipeline and solved. Because the mathematical model can not completely express the molecular motion law, we used Monte Carlo method program to solve the problems which the mathematical model can not solve. The program results matched very well with the first flight mathematical model results, that is to say the program we compiled is correct and credible. The program made classified discussion on the gas molecules which pass through the long straight cylindrical pipeline, and compared the contribution degree to the beaming effect of the molecules directly passed through the long straight cylindrical pipeline with post-collisional indirect passed through the long straight cylindrical pipeline. This article also put forward the conception of 'the evaluation parameters of angle beaming effect ', and perfected the theory of the beaming effect evaluation parameters. The mathematical model results and the Monte Carlo simulation results show that the classical beaming effect theoretical model existing error.
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