Study On The Dynamics Of Axial Flow Check Valve Closing Process

When the pump stop suddenly the role of the check valve is to protect the drive before the device is not damaged,axial flow check valve because of its flow resistance coefficient is small,smooth operation,the advantages of small noise,is widely used in long pipeline system,its performance advantages and disadvantages,the length of life,work reliability will affect the valve before the drive device and the entire pipeline system safety,in order to ensure that the axial flow check valve in the various conditions of safety and reliability,it is necessary to carry out a lot of verification,the traditional experimental method is bound to consume a lot of manpower and material resources,numerical simulation technology in recent years become a reliable research method,cost savings.This paper takes the axial flow check valve as the research object,studying the dynamic characteristics of the valve discs and the dynamic response characteristics of the valve discs impact valve seat instantly when the pump is stopped.The contents of this paper are summarized as follows:(1)Combined with the curve of centrifugal pump full characteristic,analysis of the centrifugal pump working state when pump stop suddenly,getting its working state is still maintained in the normal area,the normal area is divided into pump conditions,braking conditions and turbine conditions,thus get the change curve of the inlet flow of the check valve,the flow rate changes with the time as a cosine function,using C language written UDF program as the check valve inlet boundary conditions;(2)Simplified check valve model,analyze the force of the valve in the process of closing,obtain the valve flap power equation,combined with the dynamic equation using C language to write the disc driver,after compiled and connection,combined with the known boundary condition,to study the axial flow type check valve dynamic closing characteristics when the pump stop suddenly in the CFD,the movement law of the valve disc under the action of the dynamic force and the spring force,the velocity of the valve disc and the sealing surface of the valve seat,the law of the fluid dynamics of the valve chamber and the law of the medium flow change are obtained;(3)Simplified check valve model,the ANSYS Workbench combined with LS-DYNA technique was used to transient simulate the process of the sealing surface impact the valve seat.Obtained the stress and strain cloud map of the valve disc and the valve body at each time point,and the stress and strain curve of the valve and the valve body in the period of 0 ~ 5ms.Analyze the dynamic response of the valve disc and the valve body,getting the contact time and the stress and strain variation of the valve seat and body and its maximum.In the course of the collision,there is energy conversion and absorption between the valve disc and the valve body,the system absorbed about the energy is irreversible;(4)Based on the spring damping model,the impact dynamics is used to derive the collision process of the valve disc and the body and verify the reliability of the simulation.In the process of derivation,the damping coefficient c is difficult to be determined,therefore,the k-c curve is obtained by using the dynamic formula in Maple,obtained the c value of this topic,based on the known condition theory,the velocity of the valve disc after the collision is deduced by combining the known condition theory,and the relative error is less than 5% compared with the finite element analysis,and proved the reliability of finite element analysis.