Abstract: A numerical analysis of air-water two-phase flow characteristics in helical square ducts was made using the CLSVOF (coupled level set and volume of fluid) multiphase model. The range of gas superficial velocity was 0.1—2.5 m·s^-1, and liquid superficial velocity was 0.09—4.5 m·s^-1. An investigation of effects of curvature diameter and helix angle on flow pattern transition was made. The air-liquid two-phase flow pattern map was drafted under different flow conditions. Compared with the traditional interface tracking method, the CLSVOF method could get a more accurate gas-liquid interface. With helix angle increasing, the conversion boundary from plug flow to bubbly flow moved towards decreasing U_L, but only slightly. The conversion boundary from plug flow to slug flow moved towards decreasing U_L. With coil diameter increasing, the conversion boundary from plug flow to bubbly flow moved towards decreasing U_L. The conversion boundary from plug flow to slug flow moved towards decreasing U_L and increasing U_G. Flow pattern transition was different from Murai flow pattern.

Key words: helical ducts, gas-liquid flow, CLSVOF model, numerical simulation, computational fluid dynamics

摘要： 采用CLSVOF(coupled level set and volume of fluid method)方法,以空气和水为介质对矩形截面螺旋管内气液两相流动进行数值模拟,气相折算速度U_G为0.1～2.5 m·s^-1,液相折算速度U_L为0.09～4.5 m·s^-1.研究螺旋直径、螺旋升角对流型转换边界的影响,并绘制了不同螺旋直径、不同螺旋升角下的流型图.数值结果表明,与传统VOF方法相比,CLSVOF可以得到更精确的相界面;随着螺旋升角的增加,塞状流向泡状流的转换边界向U_L减小的方向进行,但是幅度很小,塞状流向弹状流的转换边界向U_L减小的方向进行;随着螺旋直径的增加,塞状流向泡状流的转换边界向U_L减小的方向进行,塞状流向弹状流的转换边界向U_L减小、U_G增大的方向进行;与Murai流型图相比,流型转换边界有所差异.

关键词: 螺旋管, 气液两相流, CLSVOF模型, 数值模拟, 计算流体力学