基于CFD有压管道水锤特性

Water hammer characteristics in pressurizedpipeline based on CFD

为了进一步揭示管路系统在不同流动条件下的水力过渡过程,降低水锤危害,以简化的直管路系统为研究对象,采用数值模拟方法对其关阀水锤进行了研究.基于SST k-ω湍流模型对直管路系统具有连续水柱的水锤现象进行了三维CFD计算分析,同时采用VOF多相流模型耦合Schnerr-Sauer空化模型对直管路系统伴有水柱分离的水锤现象进行了研究,得到了直管路系统在不同稳态初始流速和关阀方式下的瞬变流特性.研究结果表明:稳态初始流速较小时,不会产生水柱分离现象,稳态初始流速较大时,容易产生水柱分离现象;水锤波的传播大致可以分为4个阶段,水锤压力会在耗散作用下逐渐衰减,水柱弥合时会造成更大的水锤压力;稳态初始流速和关阀方式对水锤压力具有重大影响,水锤压力随着稳态初始流速的增大而增大,最大水锤压力与稳态初始流速近似呈线性关系,阀门“瞬间关闭”时水锤压力最大,“先慢后快”关闭时水锤压力最小.该研究对有压管道的水锤防护具有一定的指导作用.

To further reveal the hydraulic transition process of pipeline system under different flow rates conditions and reduce the harm of water hammer,the simplified straight pipeline system was taken as the research object,and the valve closing water hammer was studied by numerical simulation.Three-dimensional CFD numerical calculation of valve closing water hammer with continuous water column in straight pipeline system was carried out based on SST k-ωturbulence model,and the VOF multiphase flow model and Schnerr-Sauer cavitation model were used to study the water hammer phenomenon with water column separation in straight pipe system,and the transient flow characteristics of the straight pipe system under different steady-state initial velocities and valve closing schemes were obtained.The results show that when the steady-state initial velocity is small,water column separation will not occur,but water column separation will exist when the steady-state initial velocity is large,the propagation of water hammer wave can be approximately divided into four stages,the water hammer pressure will gradually decay due to dissipation,and greater water hammer pressure will be caused when the water column is closed.The steady-state initial velocity and valve closing scheme have a great influence on the water hammer pressure,the water hammer pressure increases with the increase of steady-state initial velocity,and the maximum water hammer pressure is approximately linear with the steady-state initial velocity.When the valve is closed instantaneously,the water hammer pressure is the maximum.When the valve is closed slowly first and then fast,the water hammer pressure is the minimum.Thus,the study has a certain guiding effect on water hammer protection of pressurized pipeline.