Research On Structural Characteristics Of Air Valve Protecting Water Hammer

China is short of water resources on the whole,and the distribution of water resources in time and space is extremely uneven.However,the weight of residential water use increases year by year.The situation of water resources shortage has become an important factor restricting the development of national economy in China,especially in northern cities.In order to solve the regional difference of water resources distribution and the increasingly sharp contradiction of water supply demand,it has become an inevitable development trend to build trans-regional and trans-basin long-distance water supply projects,most of which are pump station water supply projects.In the way of pressurized water conveyance of pump station,the water pipeline line is easy to be affected by the terrain and other buildings,and often fluctuates greatly.After stopping the pump water hammer,the pipeline will have alternating pressure fluctuations of positive and negative pressure,causing pipeline damage.Air valve with good negative pressure water hammer protection and control the function of the volume of a gas in the tube,has now become a water supply system is an important line of hydraulic components and the mainstreamproducts,but there is no direct air valve design,manufacture and test of unified standards,product quality is large,especially when the floating ball pressure level is not enough to cause deformation damage,air valve lose of water hammer protection.In this paper,combined with the new stone coal coking water supply project,the structural characteristics of the air valve protection water hammer and the force of the float ball are studied,the main content is as follows:(1)The research status of the water hammer effect of air valve protection and the strength calculation of float ball at home and abroad are reviewed;(2)Based on the structure and hydraulic characteristics of different types of air valves,the working principle,selection and arrangement principles and the failure reasons of hollow air valves in practical water supply projects are systematically described;(3)According to the steady-state calculation mathematical model of pump station,the basic theory of transient flow and the method of characteristic line,the water hammer calculation model of pressurized water conveyance pipeline is deduced.Combined with the hydraulic effect analysis of the water hammer of air valve protection for the new coal coking water supply project,the pressure distribution of the pressure pipeline is determined.On this basis,the structural characteristics of the air valve are analyzed;(4)According to the structural dimension diagram of air valve,3d geometric model of float ball and metal seat was created in Workbench DMmodule,material characteristic parameters were customized to set,contact types between upper and lower hemispheres of float ball and metal seat were established,and finally meshing was conducted to complete the creation of finite element model of float ball;(5)Finite element analysis software-Ansys Workbench finite element statics for the air floating ball valve is calculated,according to the actual stress condition of the floating ball,the finite element model of the corresponding boundary conditions,the upper and lower hemisphere the same wall thickness of the structure of the floating ball in the different wall thickness,water pressure load,the material,the contact with the seat Angle parameters such as the stress calculation of the ultimate goal for the design of air floating ball valve and provide technical support to the safe operation of water supply system.