高压流体过冷流动沸腾的数值模拟

Numerical simulation for subcooled boiling process of high pressure liquid

在二流体模型基础上,采用RPI模型计算加热壁面的相间质量传输,对竖直圆管内高压流体过冷沸腾流动过程进行数值模拟。研究发现:壁面温度沿流动方向有明显拐点。根据壁温变化趋势可以判断,转折点位置即为过冷沸腾起始点;管内流体速度的增长曲线并不是简单单调递增的过程,而是速度增长由刚开始的缓慢上升到急剧上升,与空泡份额的分布曲线相似。气相速度高于液相速度,气液二相速度差沿流动方向逐渐加大。压降方面,与管内单相流动相似,压力损失主要来源于重力压差。数值模拟结果与已有的实验数据吻合较好,证明了计算模型的正确性。

A numerical study was performed for subcooled boiling process of high pressure liquid on the basis of two-fluid model,the RPI model was used to calculate the mass transfer on the heating wall between two phases.The results show that there is an obvious turning point of wall temperature along with flow direction,which demonstrates the onset point of subcooled boiling according to the variation of wall temperature.The fluid velocity is not in linear increase,which increases gradually at first and then increases sharply,and is similar with that of void fraction.The gas-phase velocity is higher than that of liquid-phase and their difference increases gradually along with flow direction.The variation of two-phase pressure difference is similar with that of single-phase flow,which is mainly the gravity pressure difference.The simulation results meet with experimental data better,which verifies the accuracy of computational model.