Study On Calculation Of Fluid-solid Coupling Water Hammer In Pressure Pipeline Of Hydropower Station

The pipeline is a very important component of water diversion and transportation,the valve or pump connecting the pipeline will be constantly opened and closed(stopped),opening and closing the valve or pump will cause the fluid pressure inside the pipeline increasing or decreasing due to the hydraulic transient process,when the hydraulic transient process is serious which will produce waterhammer in the pipeline.The occurrence of waterhammer will have a great impact on the safe operation of the pipeline system,because of the tremendous pressure increase or decrease in the pipeline system.When the constraint form of pipes is the weak constraint form(in addition,underground buried pipelines have the strong constraints can not be defined as a weak constraint pipeline),the high pressure will lead to the pipeline's vibration,and the pipeline's vibration will cause the new hydraulic transients process,so the mutual coupling effect will happen in the pipeline system,the coexistence of two kinds of medium pipeline's and fluid's motion,which is called the effect of pipeline system's fluid-structure-interaction.The theory of water hammer can be divided into classical waterhammer theory and fluid-structure-interaction waterhammer theory.The classical theory of water hammer can be dated to as early as 200 years ago which was proposed by some scholars,the theory which has the conditions of less consideration of the real conditions and a lot of simplification,without considering the dynamic characteristics of the pipeline,because the theory in actual industrial production process is simple,its accuracy is not high,but in the past years it has been widely used.With the progress of society and development of science and technology,especially the application of the numerical calculation since 1960s is developed such as the finite element method numerical solution technique,fluid-structure-interaction method makes the waterhammer problem attracted the attention of majority of experts and scholars.In the recent decades,the development of the fluid-structure-interaction waterhammer method has undergone a process from simple to complex.Based on the classical waterhammer's theory,we summarized the mathematical model and the solving method(method of characteristics,MOC)of the classical waterhammer's theory.Then we summarized the calculation program of fluid model and structure model of ADINA software used in the equation and its discrete form.Finally,the numerical simulation of the problems in this paper is done by using the FSI solver module of ADINA software.The specific process is:classical theory of waterhammer used in the second chapter is contrasted with FSI waterhammer's theory in the third chapter to calculate the same model for contrasting and illustrating the use of the necessity of FSI method to calculate water hammer;then I use ADINA software to calculate different valve closing time's,different pipe length's and different wall thickness's waterhammer problem.The numerical simulation of waterhammer is based on the FSI theory;last we get the pressure pipeline of Dandy University's fluid-structure-interaction experimental data and the FSI calculation based on ADINA to compare and verify the rationality of the use of FSI waterhammer theory in this paper.