重力流关阀极限水锤特征及阀门关闭规律研究

Limiting Water Hammer Characteristics of Gravity Flow Valve Closing and Corresponding Valve Closing Law

长距离重力流输水工程关阀水锤是威胁管道系统安全的重要因素之一。首先分析了重力流关阀的极限水锤特征,将重力流末端关阀产生的极限水锤特征分为两个阶段,第一阶段为静水头值的恢复段,此段管线压力呈上升趋势,上升速率受关阀速率控制;第二阶段为水锤压力的波动段,当管线压力恢复到静水头值后,水锤波特征逐渐明显,压力最大值受到该段关阀速率控制。进一步推导了极限水锤压力最大值的理论计算公式,并结合水锤特征解释了长距离重力流输水工程最大关阀水锤压力取决于第二阶段关阀规律。再以某实际长距离重力流输水工程为例,模拟末端关阀过渡过程,分析不同关阀规律下系统的水锤压力,验证了重力流关阀水锤特征和理论计算公式,并在此基础上提出了分阶段关阀速率和折点开度的选择方法。

The closing of valves causing water hammer is a critical threat to the safety of longdistance gravity flow water transmission projects in pipeline systems.The limiting water hammer characteristics of the gravity flow valve closing were initially analyzed,and the resulting characteristics could be divided into two stages.The first stage involved the recovery of static water head value,during which the pipeline pressure showed a rising trend that was controlled by the valve closing rate.The second stage involved the fluctuation section of water hammer pressure.As the pipeline pressure returned to the static water head value,the water hammer wave became gradually more apparent,and the maximum pressure was controlled by the valve closing rate in this section.The theoretical formula for the maximum limit of water hammer pressure was further derived.It was explained that the maximum water hammer pressure depended on the second stage valve closing law of long-distance gravity flow water transmission projects,in combination with the characteristics of water hammer.Using an actual long-distance gravity flow water transmission project as a case study,this paper simulated the transition process of end valve closing,analyzed the water hammer pressure of the system under different valve closing laws,and verified the water hammer characteristics and theoretical calculation formula of gravity flow valve closing.Based on this rationale,a method for selecting the rate of valve closing and the opening of the break point was proposed.