Analysis of The Roll Stabilizing Effect of a U-Tube Tank for A Ship in Regular Seaway (Published)
Ships in turbulent seas suffer a lot of unstable motions which translate into discomfort of ship’s crew and passengers and this also creates unfriendly working environment on the main deck for the crew members. To stabilize the vessels in one degree of freedom, a u-tube tank was designed and introduce to damping the roll motion. A U-tube tank has a separated port and starboard portions connected by a channel between them. For a rolling ship, the U-tube tank can be used as a damper to reduce roll motion of the ship quickly. The damping ratio is usually tuned through the size and shape of a valve in the connecting channel of the u-tube. When the tank is turned off RAO reaches a peak value of 12 at a frequency of 0.1 Hz and the RAO remains constant at the value of 0 as the wave encounter frequency increases as the tank is turned on. Active control of ship roll motion is studied using a U-tube water tank as actuator. For the predictive control, system identification is applied to update the parameters of the linear ship roll model with a u-tube tank when the ship dynamics changes.
Keywords: Amplitude, RAO, Roll Motion, U-Tube Tank, damping