Analysis And Optimization Of The Opening And Closing Process Of Check Valve Considering Fluid-structure Coupling

Check valve is mostly used in pipeline system,which can ensure that the pump in front of the valve will not be damaged by the return flow force,and plays a role in protecting the safety of the system.As a kind of check valve,axial-flow check valve has the advantages of low flow resistance in fully open state,fast opening,fast check,etc,so it is widely used in pipeline system.In the working process of the check valve,due to the effect of the flow force on the valve disc,the calculation of the force on the valve disc becomes extremely complex,and it is difficult to determine the movement state of the valve disc.At present,there is no complete design system for the research of the check valve in China,and some designed products have the problems of too long opening time,too large flow resistance under the fully open state,and too high impact speed of the valve disc on the valve seat during the check process.Aiming at the above problems,this thesis will analyze and optimize the opening and closing characteristics and drag reduction characteristics of the existing axial-flow check valve products by changing the structural parameters of the valve and using numerical simulation technology.The main work is as follows:(1)Firstly,introduce several typical design methods of revolving body,and analyze the advantages and disadvantages of each method.Secondly,determine three parameters which have greater influence on the valve core rotary profile,and design the check valve core profile through using the Nystrom rotary design method.Finally,combined with the Venturi effect and the flow channel profile formula,the flow channel profile of the valve body at the inlet of the check valve and the cavity of the valve body is determined.(2)The orthogonal experimental design is carried out for the three parameters which have the greatest impact on the valve core structure,afterwards work out twenty-five groups of permutations and combinations with orthogonal distribution in space.Following the performance of three-dimensional modeling for the twenty-five permutations,the flow resistance of the valve is analyzed by numerical simulation software.Then through variance weight analysis of the numerical simulation results,it is found that the biggest factor,which affects the flow resistance of the check valve in fully open state,is the maximum diameter of the valve core,the correction coefficient of the disc profile is next,and the correction coefficient of the deflector profile is the smallest.Moreover,Kriging surface interpolation method is used to perform surface fitting on the flow resistance results of twenty-five groups of axial-flow check valves in orthogonal experiment.Finally,the Kriging surrogate model is further optimized by adopting genetic particle swarm optimization algorithm,after that the optimal spool structure is selected to minimize the flow resistance of the check valve.Based on the results of fluid analysis,fluid-solid coupling is employed for the valve,and it is analyzed that the maximum displacement of the valve is at the middle cavity of the valve body,and the extreme value of the equivalent stress is at the rear tail position of the valve core.(3)Fluid analysis software is used to simulate the change of internal fluid movement state over time during the opening and closing process of check valve.And analyze the minimum opening speed and full opening action time of the valve;after the pump stops working,dissect the dynamic response curve of the check valve,and by adding the reverse blocking structure on the valve body of the axial-flow check valve,the impact speed of the disc on the valve seat during the check process of the check valve is reduced.