Research On Improvement Of Water Hammer Calculation Based On Traditional Water Hammer Theory

In a pressurized pipeline system,water hammer is the phenomenon opening and closing of the valve in the pipe system and the opening and closing of the guide vane of the hydroelectric turbine.The fluid flow velocity in the system causes the fluid pressure in the pipe system to rise and fall greatly in a short time.In a practical project,a series of changes in the fluid flow state such as the opening and closing of a gate valve,the sudden stop of a water pump,and the opening and closing of a faucet in a living system may cause water hammer.Therefore,the phenomenon of water hammer often occurs in an industrial pipeline system.The instantaneous rise and fall of the fluid pressure in such a pipeline can lead to severe vibration,deformation,and even rupture of the pipeline system.Therefore,it is very important to explore the changes in water hammer pressure and velocity in the pipeline.The study of this law of change requires a comprehensive set of water hammer theory and water hammer calculation methods.Although the classic water hammer theory is available,the classic water hammer theory can also be improved,making the classical water hammer theory more perfect.This thesis firstly introduces the traditional water hammer theory and pushes forward the classic differential equations of water hammer,and then puts forward the possible improvements found in classical water hammer theory.In particular,when the water hammer pressure and the water hammer wave velocity were deduced,the problems of the pipe inclination,pipe wall friction and stress wave were not considered.And the deduction of the basic equation of water hammer and water hammer pressure,the object of study of water hammer wave speed is inconsistent.Therefore,this paper will re-introduce the improved water hammer pressure and water hammer wave velocity formula based on the questions raised by oneself.In addition,the basic equations of the water hammer that consider the stress wave of the pipeline and the equations of the elastic equation and the elastic equation of the pipeline constitute the axial 4-equation.The differential equations of the water-shock basic differential equations after deformation using the direct difference method are analyzed and compared with the traditional equations by the characteristic line method.The reliability and rationality of the improved equations are verified.Finally,the dissertation discusses whether the water hammer wave propagates in the pipeline system at a fixed value.The improved basic equations of water hammer calculation in this thesis can be used to calculate the change law of water hammer pressure,pipe cross-sectional area,liquid density and liquid flow rate with time,which is more reasonable and consistent with the actual pipeline.The research of this thesis has further improved the basic theory of water hammer and it is of great significance for the practical application of the project.