流动沸腾汽泡脱离直径尺寸分布研究

沸腾是一个复杂的换热过程，大量实验表明，不同核化点的脱离直径存在区别，即使在同一工况下，同一核化点产生的汽泡脱离直径也会大小不一，因此汽泡尺寸分布不可忽略。尽管目前已有较多用于汽泡平均尺寸的计算关系式，但对于尺寸分布的研究仍较少。因此，本文针对流动沸腾下汽泡脱离直径的尺寸分布进行研究，对比常用的伽马函数和正态分布函数描述这一分布时的准确度，确定概率函数后，再对概率密度函数中两个重要的参数均值和标准差进行分析，最后得到一套预测不同工况下汽泡尺寸分布的关系式，该关系式准确度较高，并考虑了壁面过热度、质量流速等因素的影响。

Study on Bubble Size Distribution in Flow Boiling

Boiling is a very complex heat transfer process. According to experiments, bubbles produced at one nucleation site have different sizes and the mean bubble departure diameter is even different at different nucleation sites under same working conditions. Thus, the distribution of bubble size cannot be ignored. Nowadays, a lot of semi-empirical correlations were proposed in predicting bubble departure diameter, but the study of bubble size distribution is rare. Therefore, this paper focused on the bubble size distribution. Firstly, the accuracy of Gamma distribution and Gaussian distribution was compared based on the experimental data. Then, two determined parameters, such as average and standard deviation were analyzed respectively. Finally, a set of bubble departure diameter distribution correlations for flow boiling was obtained which could reflect the distribution of bubble departure size in different mass flux, wall superheat.