Comparative Study On Theoretical Calculation Methods Of Water Hammer For Transient Flow In Pressure Pipelines

Summary As an important water conveyance structure,pressure pipelines are used more and more widely in water conservancy projects,and the non-constant flow phenomenon-water hammer will occur during its operation.The water hammer phenomenon will have an adverse effect on the water pipeline system: if the generated water hammer pressure is too large,it may cause the water pipeline to burst;if too much negative pressure is formed,it may cause cavitation in the pipeline.The rapid change of the pressure in the pipeline will also cause the vibration of the pipeline,and the vibration of the pipeline will affect the movement of the water flow.The interaction between this structure and the fluid is called fluid-solid coupling.The research on water hammer theory and its calculation methods have many years of history.They can be divided into three categories: classic water hammer theory,water hammer theory considering liquid compressibility and tube wall elasticity,and fluid-solid coupling theory.However,different theories have their own advantages and disadvantages.Through the study and thinking of many "water hammer" literatures,we have clarified the classic water hammer theory,the water hammer theory considering liquid compressibility and pipe wall elasticity,and the fluid-solid coupling water hammer theory and its solution methods.First,through Matlab programming,use the characteristic line method to solve the model case of the classic water hammer theory,and summarize its rules;secondly,through Matlab programming,use the diffusion scheme difference method to analyze the model cases considering the liquid compressibility and tube wall elastic theory.Solve,and summarize its rules: again,use Hypermesh to model,import ADNIA for some settings,perform fluid-solid coupling water hammer calculation and analysis.Finally,the results of the three water hammer calculation theories are compared and analyzed: 1.The maximum water hammer pressure of the three theories is inversely proportional to the valve closing time;2.The classical water hammer theory has the slowest attenuation of the water hammer pressure and the flow The solid-solid coupling theory is the fastest and the attenuation trend of the fluid-solid coupling theory is obviously different from the previous two theories.3.The classical water hammer theory does not show a significant difference in the maximum water hammer pressure and the theory of compressibility and tube wall elasticity.The maximum value of the three theoretical water hammer pressures during a certain valve closing period is the same as the growth rate.5.When the valve is closed too fast,the maximum value of the fluid-solid coupling theoretical water hammer pressure is smaller than the first two theories and the difference decreases with the shortening of the closing time.Increase;6.The maximum value of the three theoretical water hammer pressures is proportional to the length and wall thickness of the pipe.