Research On The Rule Of Cavitation Evolution In The Process Of Butterfly Valve Control

Butterfly valves are widely demanded by the market due to their high safety and low manufacturing costs.However,with the development of society and the progress of industry,more and more harsh working environments also put forward higher requirements for the performance of butterfly valves.When the butterfly valve adjusts the flow at a small opening or works at a high incoming flow speed,the butterfly valve often forms a local low pressure area due to the change of the flow area,and cavitation occurs in this area.Cavitation is often accompanied by vibration and noise,at the same time,it affects the flow capacity of the butterfly valve and causes cavitation wear,damage the structure of the valve body and the rear pipeline.Therefore,it is very important to carry out research on the mechanism of cavitation flow inside the butterfly valve,and to explore the influence of different butterfly valve plate structures on the cavitation phenomenon behind the valve.With the development of computer numerical simulation technology and the support of related theories of fluid mechanics,more and more scholars have begun to conduct related research and design on butterfly valves through numerical simulation methods.This paper first verifies the accuracy of the numerical simulation through related experiments,and then uses Fluent to numerically calculate the internal flow under different flow and structural parameters,and obtains the internal flow field parameter information of the butterfly valve under different working conditions(pressure,velocity,streamline,etc.).At the same time,the internal cavitation characteristics of the butterfly valve under different working conditions are studied,and the cavitation occurrence area and the backward development process of cavitation under various working conditions are explored.Aiming at the areas prone to cavitation,the evolution mechanism of cavitation in the butterfly valve was obtained,and the influence of different valve plate structures on the characteristics of cavitation after the valve was explored,The main conclusions are as follows:1.The flow performance of the butterfly valve will continue to increase with the increase of the valve opening.As the incoming flow rate increases,a wide range of highspeed jet areas and low-pressure areas will appear inside the valve body,which will affect the stability of the valve and cause cavitation.The generated cavitation will affect the flow performance of the butterfly valve,and collapse due to pressure recovery during the backward movement of the main flow.2.When the butterfly valve is operating at a small opening,the inner arc-shaped valve plate edge will cause the fluid to generate more vortices here,and the low pressure at the center of the vortex will induce more cavitations to form a larger jet and pressure difference.Changing the edge structure at the oncoming surface will change the distribution of pressure gradient and velocity gradient on the contraction section,thereby affecting the intensity of cavitation phenomenon behind the valve.Driven by a strong back pressure gradient,the re-entrant jet will move to the recessed area behind the plate,so changing the edge structure at the back flow surface will not have a great impact on the flow at the gap.3.When the flow velocity is high,the increase of the valve stem size will affect the movement of cavitation above the valve plate and hinder the forward flow of the reentrant jet at the rear edge of the valve plate.The change of flow state speeds up the frequency of cavitation falling off,affecting the way of falling off cavitation bubbles,reducing the size of falling off cavities,thereby changing the intensity of cavitation occurring in the valve body.