Research Study On Calculation Of Butterfly Valve Dynamic Hydraulic Moment And Elimination Of Butterfly Plate Oscillate

Although China is a big country of butterfly valve,it is insufficiently related to valve related theoretical research,leading to large and not strong valve industries.Butterfly valve is widely used in chemical enterprises,space sectors and nuclear power systems,but the industrial circles of the butterfly valve is not uniform,resulting in a large difference in calculation results,which affects the correct selection of the valve opening and closing actuator.This paper uses numerical simulation law and experimental law on penetration and hydrodynamic characteristics of butterfly valve,research work plays a positive role in improving butterfly valve theory design levels.The main research work in this paper is as follows:(1)Aiming at the problem that the existing various butterfly valve dynamic hydraulic moment calculation methods at home and abroad are diverse and the calculation results are hugely different,this paper derives a new dynamic hydraulic moment coefficient calculation formula based on the plane potential flow theory.(2)A wind tunnel test bench was built,and the dynamic hydraulic torque of the butterfly valve at different opening degrees was measured in the experiment,and the derived dynamic hydraulic torque coefficient calculation formula was verified and corrected.(3)Aiming at the problem of the small range of the Re number measured in the experiment,CFD-Fluent software was used to calculate the dynamic hydraulic torque coefficient of the butterfly valve.On the basis of verifying the reliability of the numerical simulation,the calculation formula of the dynamic hydraulic torque coefficient was revised again.Expanded the application range of the formula.(4)There are two situations in which the hydrodynamic moment coefficient increases with the opening degree.One is that when the fluid in the confined space flows through the butterfly plate,the hydrodynamic torque coefficient decreases with the increase or decrease of the opening;the other is the hydrodynamic torque coefficient generated by the fluid flowing through the butterfly plate in a large space.As the opening degree increases,it first increases and then decreases,reaches the maximum at about 30°,and then begins to decrease.Whether in a confined space or a large space,with the increase of Re,the hydraulic torque coefficient of the butterfly valve increases,but the increase is very small.(5)Aiming at the problem of butterfly plate oscillate in large-diameter butterfly valves,the dynamic grid technology is used to simulate the movement behavior of the butterfly plate under the action of flow-induced vibration.Studies have shown that the formation and shedding of the rear vortex of the butterfly plate are the main reasons for the oscillate of the butterfly plate;therefore,this paper optimizes and designs the structure of the butterfly plate from the perspective of the formation and shedding of the vortex,that is,adding spiral ribs on the lower surface of the butterfly plate.The plate restrains the formation and shedding of the vortex behind the butterfly plate,increases the lift force,enables the butterfly plate to remain fully opened,and solves the problem of butterfly plate oscillate.