基于查询表的环状流初始携带份额分析计算

Prediction of entrainment fraction at onset of annular flow based on 2006 CHF look-up table

气液两相流临界热通量对工业设备的安全性有重要影响,液膜干涸模型是预测气液相环状流临界热通量的有效方法。确定环状流起始点、初始和平衡状态的携带份额、携带现象的发生条件、液滴沉积率以及携带率对模型的计算精度都起着决定性的作用。通过大量研究目前已经得到了适用于不同条件下的经验关联式来预测此模型中的大多数参数,然而环状流起始点的初始携带份额至今仍需通过假设来确定。以广泛应用于核工业的临界热通量查询表为依据,针对界限含气率区间建立环状流液膜干涸模型,对使模型计算值满足查询表工况的初始携带份额进行分析,拟合得到其与Weber数及液相Reynolds数的关联式,预测值偏差大多在±30%内。

The critical heat flux （CHF） of gas-liquid flow plays an important role in the safety of industrial equipment. At present, the liquid film model is widely used for predicting critical heat flux in gas-liquid annular flow. It consists of onset of annular flow, entrainment fraction for the onset point and the equilibrium state, inception criteria for droplet entrainment, droplet deposition and entrainment rates, which all have decisive effect on prediction accuracy. Most parameters in this model can be determined by some empirical correlations valid under different conditions. However, up to now, the entrainment fraction for the onset of annular flow is always assumed. In this paper, the normalized data of the 2006 CHF look-up table adopted widely, especially in the nuclear industry, were used. The liquid film model was built for the limiting quality region. The entrainment fraction at the onset of annular flow was obtained when the predicted CHF of the model met the values in the look-up table. The empirical correlation including the Weber number and the Reynolds number of liquid was provided. Its prediction could mostly make the errors within ±30%.