Research On Unsteady Fluid Flow And Surge Of Stabilizer Safety Valve

Stabilizer safety valve is the second safety barrie of nuclear power plant. It keeps the integrity of pressure boundary of reactor's coolant system. But it still can not be localized in our country. The localization of spring loaded safety valve is an important project, and there are still a series of science and engineering problems to be solved.This thesis will choose one type of spring loaded stabilizer safety valve and analysis the fluid characteristic of internal flow field, the dynamic characteristic of the valve during opening, get the steady flow distribution, analysis the flow resistance coefficient and the fluid force.We establish a model of safety valve's dynamic and get its dynamic characteristic through numerical analysis. We find out that surge will occur during this process, and get the surge frequency, mass quality and maximum location of the valve. Through modal analysis, we get the natural frequency of safety valve, and compare to the surge frequency to see if resonance would occur.Finally we discuss several ways to reduce surge. Through the optimization of the flow field and adjusting the spring stiffness, the surge effect get reduced. The valve will reach the maximum opening in a short period. We can see that the spring stiffness has great impact on the surge of safety valve.The theoretical study of this thesis is important to the localization of safety valve. The study of impact of spring stiffness to the surge of safety valve provides theoretical basis on the choose of spring.