地形起伏管道油流携水机理研究

This project presents an interesting approach to deal with the problem how to purge the water deposited in some low sections along the hilly-terrain pipelines, which is flushing out of the water from the pipe by the oil flow. Experimental study, mechanistic models and numerical simulation are used to investigate the characteristics of this local oil/water two-phase flow system, in which, water is deposited in some lower places while the other places of pipe are full of pure oil. Diesel, kerosene or lubricating oil and tapping water are used as test fluids. The interface profile, flow pattern, water average moving velocity, water deposition position and the critical oil velocity beyond which deposited water would move forward are measured by a lab-scale test loop. Then the mechanistic modeling is performed to explore the interface profile in the moving direction of this local oil-water two phases flow system in the up-hilly tube according to the traditional two-phase flow theory based on the published water plug model proposed by the applicant, by which the critical oil velocity would be predicted. Finally, the flow field characteristics of deposited water sheared by the flowing oil would be simulated by CFD. The flow pattern, water average velocity and critical oil velocity and the sensitivity of its influence factor were analyzed to establish a model of critical oil velocity for water withdrawn completely. This research not only is very important to the local two-phase flow theory, but also could guide how to purge the deposited water for the hilly-terrain pipelines in service.

针对地形起伏管道低洼处积液难以排除问题，提出利用上游来流连续携带低洼处积液，并采用实验测试、理论建模与数值模拟三种方法对此局部油水两相流（因管内积液存于地势较低的某些位置，其余位置为纯油）流动特性进行研究。以柴油/煤油/润滑油、自来水为实验介质，利用数据采集、影像分析等测试手段，通过室内环道实验研究局部油水两相系统界面分布及流型、积水平均运动速度、积水沉积位置、积水完全被携带的临界油速；在申请者已提出的水平管段积液界面分布规律——水塞模型的基础上，对局部油水两相系统进行理论建模分析，探索上倾管路内积水界面沿流动方向的分布规律，预测临界油速；采用CFD数值模拟方法，分析积水在油流剪切作用下的流场特征，明确不同条件下的流型、积水平均速度、临界油速及其影响因素的敏感度，建立积水可被携带的临界油速的计算模型。这不仅对局部两相流理论有重要学术价值，且对在役管道中积液的排除具有一定的指导意义。

针对地形起伏管道低洼处积液难以排除问题，利用上游来流连续携带低洼处积液，并采用实验测试、理论建模与数值模拟三种方法对油流携水这一局部油水两相流系统（因管内积液存于地势较低的某些位置，其余位置为纯油）流动特性进行研究。. 通过室内环道实验研究局部油水两相系统界面分布及流型、积水平均运动速度、积水完全进入上倾管段时的临界油速；对局部油水两相系统进行理论建模分析，探索上倾管路内积水界面沿流动方向的分布规律；采用CFD数值模拟方法，分析积水在油流剪切作用下的流场特征，明确流型、积水平均速度、临界油速及其影响因素。.随积水受到油流剪切作用增强，系统主要呈现下述流型：光滑分层流（SS）、波状分层流（SW）、油-液滴-水三层流（3SW）、油-液滴分层流（O-WDs）。积水全部进入上倾管后，在流动方向上呈不同的流型特征：上游界面呈梯度分布，可能存在界面波动（SS/SW）；中游两相产生混掺，形成液滴层，呈油-液滴-水三层波状分层流（3SW）；下游呈不均匀两相分散流，即油-水滴两层流（O-WDs）。. 提出了不稳定水塞、偏心大水滴两种理论模型以分析积水界面轴向分布规律。不稳定水塞模型认为在水塞向前运动过程中，不断有水由塞体流入塞尾，因水塞塞前没有水补充，塞体不断减小，塞尾不断变长。偏心大水滴模型认为水塞在重力等作用下演变为贴近壁面的偏心大水滴，忽略脱离积水主体的小水滴。通过与实测数据比较，确定偏心大水滴模型吻合较好。. 积水平均流速与表观油速呈线性递增关系，即Uw＝C∙Uos－UwB。定义了两个临界油速以描述积水被携带的临界条件：一是积水界面产生波动、有水进入上倾管段的最小油速，称为第一临界油速；二是全部水相进入上倾管段且平均水速大于零的最小油速，称为第二临界油速。发现第一临界油速随管径增大而指数递增、随水量增加而减小，第二临界油速随管径增大而线性增加、与积水量无关。. 上述成果不仅对局部两相流理论有重要学术价值，且对在役管道中积液的排除具有一定的指导意义。