Abstract: Experimental research on liquid evacuation was carried out for pipelines containing vertical riser sections, using air and water as medium, gas⁃liquid flow parameters were measured by high⁃speed cameras and data acquisition instruments, the liquid evacuation process is similar to the severe slug in pipeline⁃riser system. The flow characteristics at the outlet of the riser, the pressure fluctuation at the bottom and the riser pressure drop are compared. The experimental results show that when the gas pressure is low, the gas⁃liquid mixture at the riser outlet is stratified flow and slug flow, and when the gas pressure is large, it is only stratified flow. The greater the gas pressure, the faster the movement speed of the gas front, and the shorter the evacuation time. The gas front shows a tendency to break away from the upper wall surface under higher pressure, its tip is closer to the centerline of the pipe, and the slope of the liquid layer behind the gas nose is greater. The pressure at the riser bottom undergoes three processes, which correspond to the three stages of liquid production, blowout, and liquid oscillation. The greater the gas pressure, the greater the increase in pressure at the riser bottom, and the greater the corresponding peak pressure. The riser pressure drop descends more quickly and greater under higher gas pressure.

Key words: Vertical pipeline, Liquid evacuation, Gas?liquid, Two phase flow

摘要： 对含立管段的管道进行气顶排空实验研究，以空气和水为介质，利用高速摄像仪和数据采集仪对排空过程的气液流动参数进行测量，发现气顶排空过程类似于立管混输系统中严重段塞流的流动过程。对比了不同排气压力下立管出口气液混合物的流型、立管底部压力和立管压降变化特性。结果表明，排气压力较小时，立管出口气液混合物流型为分层流和段塞流；排气压力较大时，仅呈分层流。排气压力越大，气体前锋的运动速度越快，排空经历的时间越短；气体前锋表现出脱离上壁面的趋势，其尖端更加趋近于管道的中心线，气鼻后方液层坡度越大。管底压力变化经历三个过程，分别对应了立管中液体流出、液气喷发、液体震荡三个阶段。随着排气压力升高，立管底部压力增加幅度增大，对应的压力峰值增大，立管压降的开始下降时间缩短，下降速度增大。

关键词: 立管, 排空, 气液, 两相流