Numerical Study on Fluctuation Characteristics of Free Liquid Surface Under External Force

Abstract Ocean conditions can cause the steam generator in nuclear-powered ship to heave, sway and tilt with the ship, causing the free liquid surface in the steam generator to fluctuate and causing additional fluctuations of pressure and water level. In this paper, the CFD method is used to numerically study the fluctuation characteristics of the free liquid surface during the sloshing process of the secondary side liquid in the steam generator under the action of external force. The free liquid surface is tracked by using the VOF (Volume of Fluid Method) method, and additional inertial force is added through the UDF (User Define Function) to simulate rolling conditions. First, the simulation results of the numerical model in this study are compared with the experimental results, and the results are in good agreement, which verifies the reliability of the numerical model to analyze the liquid sloshing problem. Then, through numerical simulation, the fluctuation characteristics of the free liquid surface and the change of the water level and the pressure in the steam generator under different excitation periods are obtained. The results show that the liquid sloshing process in the steam generator exhibits periodic changes, and due to the complexity of the structure of the steam generator, the instability and nonlinearity of the liquid sloshing are enhanced.