Fluid-solid Coupling Analysis And Experimental Study Of Seal Ball Valve Based On ANSYS

Ball valves in the pipeline systems are mainly used for distribution, cutting and changing the direction of media flow. Ball valves have simpler structures and better seal qualities. Ball valves are smaller, lighter and material-saving. Ball valves have a rapid development in recent years due to the characteristics of its low torque, light weight and large flow. They are widely used in electricity, petroleum, coal chemical,aerospace, aviation, transportation, construction, natural gas pipelines, offshore oil,nuclear industry, agriculture and our daily life. It is crucial for valve flow field researches because fluid dynamic calculation determines the parameters and characteristics of valves. However, when the medium flow through the interior of the valves, medium force has a non-negligible influence on the sealing surfaces besides the essential spring force. It will lead to error when we just rely on the experimental data, theoretical results and lessons learned as a basis for the design of the valves. So a combination of numerical simulation and experimental methods is utilized in this paper.Universal seal ball valves are selected for the field analysis and fluid-structure coupling analysis.The main contents are as follows:1) The working principle and seal valve flow characteristics are analyzed in theory. The size of ball, stem, body, base, seat, width of the sealing surface and circle diameter of sealing surface are designed and calculated, including the sealing pressure and preload. All the data laid the foundation for the later software simulation portion2) The process of solving computational fluid dynamics is analyzed.Three-dimensional model of the ball valve and grids are conducted. Fluent software is selected to conduct the numerical simulation for several representative degree(20°、30°、40°、50°、60°、70°、80°, corresponded relative degree is 22%、33%、44%、56%、67%、78%、89%)of opening of the ball valve. Flow characteristics of the ball valve are studied by the charts of velocity distribution, pressure distribution and the velocity vector and verified by the experiments. It’s showed that the maximum velocity lies in the import and export of the valve. It’s also the area for the most serious effects of fluid.With the increase of the degree of opening, the valve reduced-pressure drops in the import and export and the fluid flow flatten while energy losses and erosion of the role of the valve are reduced. When the degree of opening of the valve is less than 40°, flow coefficient increases with the degree of opening of the valve slowly increasing. When the degree of opening of the valve is more than 40°, it increased rapidly with theincrease of the degree of opening of the valve. When the degree of opening of the valve is less than 40°, flow resistance coefficient increases with the degree of opening of the valve rapidly decreasing. When the degree of opening of the valve is more than 40 °, it is unchanged essentially.3) Fluid-structure coupling analysis is conducted by using ANSYS software.Medium pressure obtained by simulation is loaded on the contact surfaces of the ball and the fluid. In the case of considering equivalent spring force with actual working conditions and similar boundary conditions with actual working conditions, the relationship with sealing surface stress distribution along the radial position of the seat and the relationship between stress and the valve opening degree under the function of spring force and medium pressure are obtained. It’s showed that the stress along the radial sealing surface of the valve seat decreases, that is say the inside of surface has maximum stress, the outside has a contrary stress. When the degree of opening of the valve is more than 40°, the stress remains unchanged with the increase of the degree of opening of the valve. The fluid field is in a stable situation when the degree of opening of the valve is more than 40° and the influence on the sealing faces is smaller.