大泄漏率真空设备抽漏气理论计算

Influence of Large Leakage Rate on Pumping Time:A Theoretical and Experimental Study

在真空环境获得试验中,多数研究的都是高抽速低泄漏量的情况,很少有对高泄漏率进行分析研究的,但大泄漏量在工程应用中却是非常重要的部分。本文针对高抽速大泄漏量的问题进行研究,采用静态升压法来解决工程实践中经常存在的泄漏点分散和漏孔形状不规则的问题;考虑到泵组泄漏、气体成分和管道流导等因素对系统有效抽速的影响,对泵组的抽速计算进行了参数修正;通过将大泄漏量带入抽速曲线进行对比计算,得出大泄漏量对于抽气时间的影响;通过具体试验,将试验结果与理论计算结果进行对比分析,验证了模型的正确性和准确性。该理论计算方法为工程实际中存在的大泄漏问题提供了理论支持,为之后的气压控制提供了定量计算依据。

We addressed an engineeringproblemof largeleakage-rate,originated from irregular-shaped multiholes in industrial vacuum systempumped at high speed. The effective pumping speed of the ＂highly＂leaking vacuum system wasmathematically modeled,theoretically analyzed in static pressure rise method,and experimentally simulated with the lab-built test platform. The influence of the realistic situation,including the pump＇s leak,gas compositions and pipeline flow conductance,on the effective pumping speed was investigated. The time evolution of the pressure（ pumping curve） in the vacuum system with and without large leaks was calculated and measured. The preliminary results show that the large leakage-rate markedly increased the pumping time by ~ 20 min. The calculated and measured results were in good agreement,and the discrepancy possibly resulted from the non-uniform pressure distribution and increasingly tightened sealing of viton O-rings.