Ω型管的气液两相流动调整作用数值模拟研究

Numerical Investigation of the Flow Conditioning Effects ofΩ-shaped Pipe on Gas-liquid Two-phase Flows

为了开发基于流动调整机制的严重段塞流抑制方法,提出了一种新型流动调整装置——Ω型管,应用数值模拟方法对Ω型管内气液分层流的流动特性进行了研究,探讨了Ω型管的基本单元个数(N)、基本单元之间的距离(d/D)、主弯管弯曲半径与管径的比值(r/D)、入口气液相流速(气相和液相折算速度,U_(SG)和U_(SL))等结构参数和流动条件对Ω型管气液两相流动调整作用的影响规律。研究结果表明:①Ω型管能够实现"液相对气相阻塞"和"气相对液相携带"两个物理过程,从而将分层流转变为间歇流型;②增加N和提高r/D均可增加上述物理过程的循环周期,N的增加为更多气相先于液相通过主弯管(气相被阻塞阶段)提供了条件r/D的提高有利于增加主弯管上游的液相累积量,使气相能够携带更多的液相通过主弯管(液相被携带阶段),使得Ω型管下游液相含率波动性增强、气液两相流动特性间歇性增强,从而增强Ω型管对分层流的流动调整作用;d/D的增加影响作用不显著;③U_(SG)不变、U_(SL)增加有利于增加主弯管上游的液相累积量,为气相携带更多的液相提供了条件;增加P导致U_(SG)降低,会减弱气相携带液相的能力;增加U_(SG)同时减小U_(SL)虽然可提高气相携带液相的能力;但液相供给的减少会降低液相的累积量,导致因气相携带而进入主弯管的液相减小,从而减弱Ω型管的流动调整作用。以上研究结果为优化设计Ω型管、探索其气液两相流动调整机理和应用于集输管线-立管系统提供了基础。

A new flow conditioner called Ω-shaped pipe was proposed to develop severe slugging mitigationtechniques based on the flow conditioning mechanism. The flow characteristics of gas-liquid stratified flows in fi-shaped pipes were investigated through numerical simulation. The effects of geometrical and flow conditions on the flow conditioning effects of the Ω-shaped pipe were analyzed and discussed. It has been demonstrated that ： （T） the Ω-shaped pipe is capable of realizing two physical processes, namely liquid blocking to gas and gas carrying-over to liquid, through which the stratified flow is converted into an intermittent flow; （1） an increase of the count of the basic units （A〇 and the ratio （r /D） of the bend radius to pipe diameter can increase the cycle time of the above processes ; the increase of N allows more gas to pass the main bend prior to the liquid and the increase of r/D is beneficial for the liquid buildup upstream of the main bend allowing more gas to be carried over through the main bend, resultantly, the fluctuation intensity increases and both the intermittency of the gas-liquid flow and the flow conditioning effects of the Ω-shaped pipe are enhanced; an increase of the superficial liquid velocity （ USL） at a constant superficial gas velocity （ USG ） is favorable to the liquid buildup upstream of the main bend allowing more gas to be carried over through the main bend; an increase of the system pressure （ P） results in a drop of USG weak-ening the gas carrying-over capability; an increase of USG while decreasing USL can strengthen the gas carrying-over ability but induce an decrease of the liquid quantity carried-over through the main bend due to a reduced liquidsupply and buildup quantity, weakening the flow conditioning effects of the U-shaped pipe. The outcome of this study provides a foundation for designing the fi-shaped pipe, exploring the flow conditioning mechanism and apply-ing it to the pipeline-riser systems.