管道滞留气团运动特性PIV实验与数值模拟

PIV experiment and numerical simulations of behaviors of residual air mass in water pipelines

为研究有压输水管道水流速度和局部高点的管道角度等因素对局部高点滞留气团运动特性的影响,搭建有压管道局部高点滞流气团实验平台,通过激光粒子测速系统(PIV)对局部高点处的流速进行测量;结合RSM湍流模型结合VOF多相流模型,构建局部高点气-液两相流体动力学模型进行数值模拟,分析管内流速、局部高点角度和气团体积对有压管道排气性能的影响。研究结果表明,随着水流速度增大,局部高点滞留气团呈现三种状态,即无气泡产生、气团产生气泡且部分被排出、气团一次性被排出;在其他条件相同时,若气体大于一定体积,一次性将气体携带出局部高点所需的水流速度增幅将减缓;局部高点角度越大,一次性将气体携带出局部高点所需的水流速度越大。

An experimental platform is constructed to test the stagnant air mass in the top bend section(like an inverted siphon bend)of a pressurized pipeline,and water flow velocity in this bend section is measured using a particle image velocimetry(PIV)system,focusing on the influence of flow velocity and the local pipeline slopes on the motion characteristics of residual air mass.To simulate numerically the flow details in the bend section,we construct a local gas-liquid two-phase fluid dynamics model equipped with a RSM turbulence model and a VOF multiphase flow model,and use it to analyze the influence of water velocity,local pipeline slopes,and air mass volume.The results show that with the increasing water flow velocity,the residual air mass presents three flow regimes:no bubble generated,air bubble generated but discharged partially,and air mass discharged at one time.If other conditions are the same,the threshold water flow rate required for the third regime is relative low when the trapped air volume is greater than a certain value;the threshold water flow velocity for the third regime become greater at larger local slopes of the top bend section.