管内向下气液两相流动界面参数分布特性

借助双探头光纤探针测量方法，对管内竖直向下空气-水两相流动的界面参数局部分布特性进行了实验研究。实验段采用内径50 mm、长度2 000 mm的圆管，气液两相表观速度范围分别为0.004～0.077 m/s和0.43～0.71 m/s。实验结果表明，不同于竖直向上两相流动中局部界面参数径向分布呈现的“壁峰”或“核峰”型分布，向下流动中局部界面参数径向分布呈“壁峰”或“宽峰”型分布；向下流动时空泡份额截面平均值均比向上流动时大119.6%～145.0%，界面面积浓度截面平均值比向上流动时大18.8%～82.5%；向下流动时界面参数分布表现出明显的均匀化趋势。

Distribution Characteristics of Interfacial Parameter in Downward Gas-liquid Two-phase Flow in Vertical Circular Tube

Experimental study was performed on distribution characteristics of interfacial parameters of downward gas-liquid flow in a vertical circular tube with the measurement by a two-sensor optical fiber probe. The test section is a circular pipe with the inner diameter of 50 mm and the length of 2 000 mm. The superficial velocities of the gas and the liquid phases cover the ranges of 0.004-0.077 m/s and 0.43-0.71 m/s, respectively. The results show that the distributions of the interfacial parameters in downward bubbly flows are quite different from those in upward bubbly flows. For the case of upward flow, the parameters present the “wall-peak” or “core-peak” distributions, but for the case of downward flow, they show “wall-peak” or “wide-peak” distributions. The average value of void fraction in vertical downward flow is about 119.6%-145.0% larger than that in upward flow, and the interfacial area concentration is about 18.8%-82.5% larger than that in upward flow. The distribution of interfacial parameters shows an obvious tendency of uniformity.