中文摘要：

文章推导出一种计算冷包截面含汽率的数学模型；将模型计算结果与已知文献相关实验结果进行对比，验证了模型的正确性。利用该模型探讨了冷包截面含汽率的影响因素如气泡直径，工质液体的密度、粘性，加热功率等。模型计算表明：气泡直径越大，在同一截面高度处的截面含汽率越低；工质粘性越大，在同一截面高度处的截面含汽率越高。本文模型的计算结果能对冷包设计提供理论支持。

英文摘要：

A general mathematical model for analyzing and predicting the void fraction profiles in the moderator cell of a Cold Neutron Source （CNS） is developed in this paper. The model is validated by comparing the results calculated from the developed model to that published in previous literatures and that obtained in the related experiments. The model is then employed to explore the influence of various factors on void fraction profiles in the moderator cell, including the diameter of the boiling vapor bubbles, the density and viscosity of the fluid, the total heating power. The model calculations indicate that the void fraction in the moderator cell increases with the viscosity of the liquid, decreases as the size of bubbles increases, and increase linearly with the heating, power. The model and the calculation results will provide theoretical supports for the design of the moderator cell of CNS.