1K-pot节流孔对低温系统流量特性影响的模型分析

Model Analysis of the Influence of 1K-pot Throttling Orifices on the Flow Characteristics of Low Temperature Systems

^(4)He降压制冷是现阶段获取超低温的常用方法。为提高制冷效率,常使用节流孔结构降低超流氦薄膜的影响,而这种结构会制约^(4)He的循环流量。基于此,本文归纳节流孔结构中各部分的流速模型,建立一套关于抽速、限流孔径及液氦蒸发流量的数学模型。通过探究节流孔结构中抽速对流量的影响关系,在确定节流孔直径的前提下,将影响关系分为三个阶段,分别对应超流氦薄膜蒸发、1K-pot液氦蒸发和1K-pot液氦蒸发达最大流量。

^(4)He depressurization refrigeration is a commonly used method for obtaining ultra-low temperatures at present.To improve refrigeration efficiency,orifice structures are often used to reduce the influence of superfluid helium films,which in turn restrict the circulation flow rate of^(4)He.This article summarizes the flow velocity models of various parts in the orifice structure and establishes a mathematical model for pumping speed,flow limiting aperture,and liquid helium evaporation flow rate.Explored the relationship between pumping speed and flow rate in the orifice structure.With the orifice diameter determined,the relationship was divided into three stages,corresponding to the maximum flow rate of superfluid helium film evaporation,1K pot liquid helium evaporation,and 1K pot liquid helium evaporation,respectively.