竖直大圆管内两相流界面分布机理

Mechanistic study on interfacial area concentration profile of vertical two-phase flow in large circular pipe

采用光纤探针测量方法对垂直上升管中空气-水两相泡状流界面分布特性进行了研究。实验选用的圆管直径为100mm,气相、液相表观速度的范围分别为0～0.1m.s-1和0～1.0m.s-1。获得了界面面积浓度(IAC)、截面含气率、气泡直径等分布规律。通过气泡的受力分析,发现升力和湍流扩散力的综合作用导致了气泡的径向运动,而且升力对径向IAC分布的影响占主导地位;当气泡直径超过临界尺寸(5.7mm)后,升力系数变为负值,使得升力指向管中心,进而导致了IAC分布由壁峰型向核峰型分布的转变。

Characteristics of interface distribution in air-water two-phase bubbly flow in a vertical pipe was experimentally investigated by using the measurement method of optical fiber probes.The inner diameter of the circular pipe was 100 mm,and superficial gas and liquid velocities ranged from 0 to 0.1 m·s-1 and from 0 to 1.0 m·s-1,respectively.Local distributions of the interfacial area concentration（IAC）,void fraction and bubble diameter were obtained.By analyzing the forces on a bubble,it was found that lift force and turbulent dispersion force determined the radial motion of bubbles,and the former dominated the radial profile of IAC.When the bubble diameter exceeded the critical size of 5.7 mm,the distribution of IAC would change from wall peak to core peak resulting from the lift force pointing to the pipe center due to lift force coefficient changing from positive to negative.