Water Hammer Test And Numerical Simulation Research

The pressure pipeline for carrying water is an important component of the water conservancy and hydropower project.During the operation of the hydropower station,the unit suddenly discard or increase the load and the rapid opening and closing of the valve will induce the hydraulic transient process of the fluid in the pipe and even produce extreme unsteady flow phenomenon—Water hammer.The water hammer phenomenon has an adverse effect on the operation of the pressure diversion system and the unit of the hydropower station: if the water hammer pressure in the draft tube is reduced too much to form an excessive negative pressure,it may cause serious cavitation in the draft tube;if the water hammer pressure increases too much,it may cause the pipeline to burst.At the same time,the rise and fall of the water hammer pressure will also promote the weakly constrained pipeline vibrate,and the pipeline vibration will trigger a new hydraulic transient process.The mutual interaction between this structure and the fluid is the fluid-structure-interaction(FSI)in the pipeline system.The theoretical research on water hammer can be divided into classic water hammer theory and FSI water hammer theory.Classical water hammer theory has a long history,so its defects are inevitable: its derivation process has been greatly simplified,the accuracy is not high,and the influence of pipeline dynamics on fluid motion is ignored.However,due to its simplicity,it is widely used to guide actual industrial production.With the advancement of modern science and technology and the in-depth research of a large number of scholars on water hammer,the water hammer theory has been improved and optimized,and finally formed the FSI water hammer theory that considers the interaction between the dynamic characteristics of the pipeline and the fluid.FSI water hammer theory has been widely used in many fields such as water conservancy and hydropower engineering,civil engineering,petroleum engineering and so on.In this paper,based on the solution method of the classic water hammer theory and FSI water hammer theory,first we use the pressure pipe solid model to simulate the rapid opening of the valve and conduct the water hammer experiment to explore the temporary flow State transition process and pipeline vibration problems,measuring water hammer pressure,pipeline vibrate amplitude and duration curve,looking for its laws,summarizing its characteristics,and providing comparative data for numerical simulation analysis of FSI water hammer of pressure pipeline;secondly,we use numerical method of classic water hammer theory(analytic method,characteristic line method)to solve this model;Finally,we focused on the calculation principle of the ADINA finite element software for FSI problem,and the FSI water hammer model of the pressure pipeline is established based on the ADINA numerical simulation platform,and using the ADINA-FSI solver module to perform FSI water hammer calculations,analyzes and compares the results with the measured data and the numerical results of the classic water hammer theory to discuss the reasonability to use the FSI water hammer calculations,summarize the characteristics of water pressure pulsation,explore the rule of the pipeline vibration,At the same time,the basic rules of water hammer pressure extremum and valve closing time,pipe length and thickness were explored.