Finite-element Analysis Of Fluid Dynamics And Fluid-structure Interaction In Nuclear Valve

As an efficient and green resource, nuclear power has been more and more popular. However, the Fukushima Daiichi nuclear power plant accident happened in2011put the nuclear safety on an important place. Nuclear valve plays an important role in the nuclear power plant, and it is significant to ensure the rationality and security of the nuclear valve. Nevertheless, the results are different to be acquired through experiment in view of the economical and technical reasons. With the development of computer, it is an effective way to obtain the pressure field and velocity field inside the valve. In this paper, the finite-element analysis method was used to calculate the fluid dynamics and fluid-structure interaction in the hydraulic valve and the main steam isolation valve.In order to verify the rationality of the hydraulic valve design, the FLUENT software was used to simulate the flow field distribution of the fluid passageway. The calculated result of differential pressure between inlet and outlet is totally good agreement with the measured one under actual working conditions by the enterprise. The results show that when the hydraulic outlet is open, the pressure of the upper surface in hydraulic cylinder is higher than the lower one, so the valve clack moves downward. When the hydraulic outlet is closed, the pressure of the upper surface in hydraulic cylinder is lower than the lower one, so the valve clack moves upward.In order to verify the influence of the large flow rate and high pressure of steam against the main steam isolation valve, firstly, the FLUENT software was used to simulate the flow field distribution of the fluid passageway. The results show that fluid pressure in entryway is not affected by the valve openings. The pressure in entryway has no pressure difference. However, the valve openings have an effect on the fluid pressure in the outlet passage. The fluid pressure in the region which is separated by the valve disk is about1atm, and the fluid pressure in the region which is outflow is about3-5MPa.ANSYS Workbench software was used to evaluate the fluid flow impact on the main steam isolation valve with a realistic three-dimensional geometry and realistic material parameters. Five cases with various opening degrees of main steam isolation valve with fluid-structure interaction analysis were simulated to observe the flow patterns and to estimate the deformation and stress. The results show that the deformation mainly happened in the entryway, and the maximum deformation is0.0377mm. The deformation of the bottom of valve disk increases with decreasing valve opening, and the maximum deformation is0.113mm when the valve opening is10mm. The valve body has the maximum stress of24.84MPa. The valve design is safe because the allowance stress of each material is greater than the maximum calculated stress.