涡轮分子泵入口结构改进的计算研究
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摘要
针对涡轮分子泵的入口管道束流效应和涡轮端盖反射效应对传输几率的不利影响、以及大口径涡轮分子泵与小型仪器相连接的难题,本文提出分子泵入口结构的改进方案:将涡轮转子的平板端盖改成锥形反射屏结构,把过渡连接件做成圆弧过渡段结构。文中根据实际结构参数,建立了不同结构类型的计算模型,采用试验粒子蒙特卡洛方法,基于自由分子流态基本假设,利用Molflow+软件,计算了各个结构模型的传输几率。计算结果表明:当倾角α的取值范围在60°～70°、圆锥底角β的取值范围在25°～45°之间时,理论上可将涡轮分子泵的抽气速率提升5%左右。
A novel type of caliber adaptor was developed to match large inlet-diameter of turbo molecular pump and small outlet-diameter of vacuum container. The caliber adapter comprises a conical reflective screen over the flat turbine,a truncated cone with curved wall and large/small diameter flanges. The flow field in the caliber adaptor was mathematically modeled,theoretically analyzed with free molecular flow assumption and in test particle Monte Carlo method,and numerically simulated with Molflow + software. The influence of the adaptor geometry on the transmission probability was investigated for design optimization. The simulated results show that the dip-angle( α)of the truncated cone and the base-angle( β) of the conical reflective screen have a major impact. To be specific,the new caliber adaptor,with α in 60° ～ 70°and β in 25° ～ 45° ranges,theoretically increases the pumping rate of turbo molecular pump by about 5%.
A novel type of caliber adaptor was developed to match large inlet-diameter of turbo molecular pump and small outlet-diameter of vacuum container. The caliber adapter comprises a conical reflective screen over the flat turbine,a truncated cone with curved wall and large/small diameter flanges. The flow field in the caliber adaptor was mathematically modeled,theoretically analyzed with free molecular flow assumption and in test particle Monte Carlo method,and numerically simulated with Molflow + software. The influence of the adaptor geometry on the transmission probability was investigated for design optimization. The simulated results show that the dip-angle( α)of the truncated cone and the base-angle( β) of the conical reflective screen have a major impact. To be specific,the new caliber adaptor,with α in 60° ～ 70°and β in 25° ～ 45° ranges,theoretically increases the pumping rate of turbo molecular pump by about 5%.
引文
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[7]蓝增瑞.束流效应对圆管分子流导几率的影响[J].真空科学与技术学报,1987,7(1):22-27
[8]张世伟,韩进,刘坤,等.直圆管道中分子流态下“位置束流效应”的Monte Carlo法模拟[J].真空科学与技术学报,2006,26(4):295-298
[9]姬国钊.分子流态下气体分子在输运过程中分布的研究[D].沈阳:东北大学,2010
[10]张波,王洁,尉伟,等.蒙特卡罗法计算分子流状态下真空管道的传输几率[J].真空科学与技术学报,2014,34(6):571-574
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[12]杨乃恒,王继常,刘玉岱.蒙特卡罗法计算涡轮分子泵叶列的传输几率[J].东北工学院学报,1984,(01):85-90
[13]张以忱,韩晶雪,贺佳,等.基于MonteCarlo方法的圆截面直角弯管传输几率[J].真空科学与技术学报,2013,33(12):1169-1173
[14] Christina Yin Vallgren CY,Paolo Chiggiato P C,Jose Antonio Ferreira Somoza J F. Electrical Network Analysis for Vacuum Profile of MedAustron[R]. No. CERNATS-Note-2012-041 TECH,2012:1-14
[15] Kersevan R,Pons J L. Introduction to MOLFLOW+:New Graphical Processing Unit-Based Monte Carlo Code for Simulating Molecular Flows and for Calculating Angular Coefficients in the Compute Unified Device Architecture Environment[J]. Journal of Vacuum Science&Technology A Vacuum Surfaces&Films,2009,27(4):1017-1023
[16] Marton Ady R K. Introduction to the Latest Version of the Test-particle Monte Carlo Code Molflow+[C],2014
[17] Hermann M,Vandoni G,Kersevan R,et al. Simulations of the HIE-ISOLDE Radio Frequency Quadrupole Cooler and Buncher Vacuum Using the Monte Carlo Test Particle Code Molflow+[J]. Nuclear Instruments and Methods in Physics Research Section B:Beam Interactions with Materials and Atoms,2013,317:488-491
[2] Ogiwara N,Yanagibashi T,Hikichi Y,et al. Development of a Turbo-Molecular Pump with a Magnetic Shield Function[J]. Vacuum,2013,98:18-21
[3] Henning J. 2. Trends in the Development and Use of Turbomolecular Pumps[J]. Vacuum,1978,28(10-11):391-398
[4] Hucknall D J,Goetz D G. Turbomolecular Pumps[J].Vacuum,1987,37(8):615-620
[5] Flecher P,周世敦.涡轮分子泵的发展近况[J].真空与低温,1982,(02):59-65
[6]牟如意,张世伟,张志军,等.涡轮分子泵入口接管束流效应的蒙特卡洛计算[J].真空科学与技术学报,2017,37(08):753-759
[7]蓝增瑞.束流效应对圆管分子流导几率的影响[J].真空科学与技术学报,1987,7(1):22-27
[8]张世伟,韩进,刘坤,等.直圆管道中分子流态下“位置束流效应”的Monte Carlo法模拟[J].真空科学与技术学报,2006,26(4):295-298
[9]姬国钊.分子流态下气体分子在输运过程中分布的研究[D].沈阳:东北大学,2010
[10]张波,王洁,尉伟,等.蒙特卡罗法计算分子流状态下真空管道的传输几率[J].真空科学与技术学报,2014,34(6):571-574
[11] Kersevan R,Pons J L. Molflow+|A Monte-Carlo Simulator Package Developed at CERN[EB/OL]. https://molflow. web. cern. ch/
[12]杨乃恒,王继常,刘玉岱.蒙特卡罗法计算涡轮分子泵叶列的传输几率[J].东北工学院学报,1984,(01):85-90
[13]张以忱,韩晶雪,贺佳,等.基于MonteCarlo方法的圆截面直角弯管传输几率[J].真空科学与技术学报,2013,33(12):1169-1173
[14] Christina Yin Vallgren CY,Paolo Chiggiato P C,Jose Antonio Ferreira Somoza J F. Electrical Network Analysis for Vacuum Profile of MedAustron[R]. No. CERNATS-Note-2012-041 TECH,2012:1-14
[15] Kersevan R,Pons J L. Introduction to MOLFLOW+:New Graphical Processing Unit-Based Monte Carlo Code for Simulating Molecular Flows and for Calculating Angular Coefficients in the Compute Unified Device Architecture Environment[J]. Journal of Vacuum Science&Technology A Vacuum Surfaces&Films,2009,27(4):1017-1023
[16] Marton Ady R K. Introduction to the Latest Version of the Test-particle Monte Carlo Code Molflow+[C],2014
[17] Hermann M,Vandoni G,Kersevan R,et al. Simulations of the HIE-ISOLDE Radio Frequency Quadrupole Cooler and Buncher Vacuum Using the Monte Carlo Test Particle Code Molflow+[J]. Nuclear Instruments and Methods in Physics Research Section B:Beam Interactions with Materials and Atoms,2013,317:488-491