Modelling of U-tube Tanks for ShipMo3D Ship Motion Predictions

摘要

Ship roll motions in waves can be significant due to small roll damping and the proximity of ship natural roll frequency to encountered wave frequencies. Roll motions can be reduced by various methods, including bilge keels and active roll stabilization using rudders or dedicated stabilizer fins. U-tube tanks and flume tanks can also be used to reduce roll motions, and have the advantages of being effective at zero ship speed and being protected from environmental hazards such as ice. This report describes the implementation of a U-tube tank model for the ShipMo3D ship motion library. The U-tube tank model has been implemented for computations in both the frequency and time domains. Example computations for a generic frigate demonstrate the reduction of roll motions using a U-tube tank. The relative effectiveness of a U-tube tank will be greatest when a ship has small roll damping, such as a vessel with small or no bilge keels.