Impact of Branch Pipe Valve Closure Procedures on Pipeline Water Hammer Pressure: A Case Study of Xinlongkou Hydropower Station

To investigate the impact of different valve closure strategies on water hammer pressure variations in pipelines and terminal valves under accident conditions, this study focuses on the Xinlongkou Hydropower Station water conveyance project. The Bentley Hammer calculation software was used to simulate the changes in water hammer pressure in the pipeline and unit terminal valves under various valve closure scenarios. Additionally, computational fluid dynamics (CFD) was applied to analyze the dynamic effects of different factors on the water hammer in the branch pipelines of the station. The results showed that shorter valve closure times resulted in higher peak water hammer pressures, with the maximum pressure occurring at the terminal valve. Extending the valve closure time effectively reduced both the peak pressure and number of pressure oscillations at the terminal valve, with pressure fluctuations stabilizing within approximately 30 s. Two-stage valve closures led to water hammer pressures 8–14.1% higher than those from one-stage linear closures. Based on these findings, it is recommended that stations adopt a valve closure time greater than 9 s during load shedding or implement a combined strategy of fast closure (60%) and slow closure (40%). The study also revealed that the primary factors influencing the water hammer are valve closure time, number of valves, valve diameter, and valve distance, in that order, with the distance having a relatively minor impact. The results of this study provide valuable insights into valve closure strategies for water conveyance projects.