2D Flow Field Dynamic Simulation Of Nuclear Main Steam Isolation Valve

National large-scale development of nuclear power requires self-reliance in nuclear technology and home-made manufacture. Our country already has the design and manufacturing capabilities for ordinary nuclear grade valves. But the high demand valves as the Main Steam Isolation Valve (MSIV) has not yet for the completion of independent R&D which is one of the most important items of nuclear equipments in"Replace Importation by Homemade"project because of its strict technical standard and high safty coefficient.The MSIV is required to be closed within 5 seconds in accident conditions. It will produce strong fluid force which the implementing mechanism must overcome. The force may lead to the failure in the closure of the valve. Useing the Realizable k-εmodel, and the Laying method for dynamic mesh update, it could calculate the 2D flow field of MSIV with the CFD software FLUENT.First, two methods are adopted to verify the correctness of the calculation, one is comparing results between the theorem of momentum method and pressure integration method, and the second is using two different commercial software FLUENT and CFX for comparative analysis. The results obtained using different methods are basically consistent, as the research method is reasonable.And then, by the dynamic simulation of the different closing speed and the pressure drop in valve clearance process, it could understand the distribution of the flow field parameters, and find the variation of the valve plate force. There are two vertical forces to affect the valve closure, and the friction is the most important part; In a low speed, force on the valve plate increases gradually, while the fluid force accumulation is not obvious. In the transition speed, there will be backflow on the opening side. When the valve closes in a high speed, the force on the plate raises rapidly, which will lead the valve could not close normally.At last, the dynamic simulation of the steam medium is carried on. Without considering the steam condensation and phase transition, the force on the valve plate is basically the same with the air medium. Considering the condensation of steam, the flow side and the underside of the valve have a higher pressure peak, and the vertical force is also slightly higher than the force without considering the phase transition.