The Study Of Lift Model For Zero-Speed Stabilizer Based On Weis-Fogh Mechanism

In recent years, people pay more and more attention to and make increasing demands of the roll stability of ships, not only sailing but also anchoring and drifting, especially large motor yachts, warships carrying weapons, research vessels and other vessels for special operations at sea.Anti-roll tank system is the only choice for ship to reduce roll under zero speed, but the effect is not very good, it can only reach to 50% under all conditions. Fin stabilizer can reduce the most roll of the ship under high speed, but it hardly reduces the roll of the ship under low speed or zero speed. The ship which needs to reduce the roll under all kinds of ship speed has to equip two pair of anti-roll systems: fin stabilizer and anti-roll system to meet the need. The advantage is obvious, but it means that there are two systems to design and maintain. Two systems not only occupy more inner space of the ship but also increase the cost. If fin stabilizer can reduce the roll of the ship under low speed and zero speed, it means that there is only one pair of system to maintain and doesn't need more inner space of the ship. So it is important to research and analyze the lift which generates by the movement of the fin and build a lift model of the fin.This thesis mainly explains the work principle of zero-speed fin stabilizer and analyzes the reason why the zero-speed fin stabilizer can supply the lift according to the foreign references. Then compare with the principle and capability of the anti-roll tanks.Introduce hydrodynamics and theoretical models of Weis-Fogh mechanism. Lift model of the zero-speed fin stabilizer is built and analyzed according to Weis-Fogh mechanism's hydrodynamics and theoretical models.A series of signal is input including even speed, accelerate and decelerate. Matlab is used to simulate the lift of the zero-speed fin stabilizer with some different input signal. The result indicates that the zero-speed fin stabilizer can reduce roll under zero speed with sine wave input signal.