The Study On Oscillating Period And Damping Characteristics Of Ship Anti-rolling Tanks

Anti-rolling tank is popularly used in reducing ship's roll motion recently.This equipment is not only simple in structure,but also effective at any speed,so it particularly fits for ships those need special working speed.Baesd on the assumption that the motion of the ship's gravity center is ignored and the roll scope around the vertical axis through the gravity center is slightly,the fisrt part of paper gives the equations of motion and roll response characteristic of the "ship-anti rolling tank"system. The design process and relevant theory on CFD are also introduced.The experiment is the most important part for the anti-rolling tank design.The design method of tank model is discussed according to similarity theory of the fluid flow. Calculation results are compared with experimental results through the numberical simulation of free oscillations test,which verifies the reliability of numberica simulation.Then a new formula fitting to calculate the period of anti-rolling tank is presented.Damping is a major factor affecting the performance of anti-rolling tank.This paper discusses tank's free oscillation motion on the linear and nonlinear damping regular,and gives the relevant damping coefficient calculation formulas. Through the arrangements of different damping structure,the impact of damping on liquid flow condition is researched.The paper simulates the forced rolling motion numerical simulation using the dynamic grid technology. The effect of moment amplitude provided by the tank and the phase relationship with disturbance moment on damping are researched.Based on the ship's linear motion assumption, the amplitude frequency response curves of the "ship-anti rolling tank"system are getten by simulation.