扩散泵设计中的几个具体问题

Study of Several Concrete Problems in Designing Diffusion Pumps

本文根据气体动力学的二元理论论述了扩散泵喷嘴角度与喷嘴扩张车的关系，认为喷嘴角度在一定范围内变化时，喷嘴的扩张率也要作相应地改变，方能取得良好的抽气性能。与此同时，各级喷嘴之间的级间距离不该用喷帽内壁面的角度来计算，而应根据射流上界面的角度来计算。文章同时分析了一级喷嘴扩张率对返油率的影响以及直筒泵对喷嘴扩张率在结构方面的限制，提出了用凸腔泵取代直筒泵的建议，以降低返油提高抽速。

In this paper, we discussed relation between the nozzle angle and the nozzle expansion of diffusion pumps according to the binary theory of aerodynamics. We considered only when the nozzle expansion changed with the nozzle angle within certain range j that getted well speeding function. Meanwhile,all the nozzle stage distance didn't calculate with the nozzle angle,but with the angle over boundary layer of jet steam. At the same time, we analysed the effect of first stage nozzle expansion on backstreaming and limits of first stage nozzle expansion of straight tube pumps in the construction, and suggested that raised tube pumps replaced straight tube pumps, for tile purpose of decreasing backstreaming and increasing speeding function of diffusion pumps.