摘要
基于双螺杆真空泵气体输运的特点,将泵腔内级间的泄漏通道简化为不同类型的真空管路,采用相邻级间的平均压强确定不同压强下级间泄漏气体的流态,计算得到级间泄漏的质量流量。根据质量守恒定律,建立了双螺杆真空泵气体输运过程的数学模型。以渐开线型端面的等螺距螺杆真空泵为研究对象,计算分析了泵从大气压到极限真空的整个抽气过程。对不同入口压强下的级间泄漏量与抽速进行了研究,研究表明:不同的泄漏通道对级间泄漏的影响有所不同。在排气端,齿顶圆与泵腔内壁之间的泄漏通道对级间泄漏的影响较大;在吸气端,两转子齿顶齿根面之间、斜齿面之间以及凹齿面之间这三种泄漏通道对级间泄漏的影响较大。
The gas transport in the double-screw vacuum pump,from atmosphere to base pressure,was empirically approximated,mathematically modeled,numerically simulated and experimentally measured. The inter-stage leakage was assumed as the gas-flow via a small hole between adjacent sections of a rectangular pipe driven by their averaged pressure difference. The mass flow-rate of the back-flow was evaluated with the model. The leakage-path lengths and viscous/molecular flow-rates,of the constant pitch screw vacuum pump with involute end face,were calculated to understand its pumping behavior. The impact of the inlet pressure on the total leakage rate and pumping speed of each inter-stage leakage path was investigated. The simulated results show that each inter-stage leakage path has different impact on the pumping speed and total leakage rate. For example,at the highest inlet pressure,the leakage path between the addendum-circle and cavity-wall has a major impact at the exhaust side,but a minor impact at the suction side.
出处
《真空科学与技术学报》
CSCD
北大核心
2017年第4期351-356,共6页
Chinese Journal of Vacuum Science and Technology
基金
企业技术研发项目(No.102-432836)
中央高校基本科研业务经费项目(No.JZ2015HGBZ0465)
中国博士后科学基金面上项目(No.2016M590041)
关键词
螺杆真空泵
泄漏
极限真空
抽速曲线
Screw vacuum pump
Leakage
Ultimate pressure
Pumping speed curve