Experimental Study of Active T-Foil Control of Longitudinal Motions of a Trimaran Hull in Irregular Waves

摘要

High-speed ships often experience over larger ship motions in waves. Therefore, high-speed ships without motion control hardly have practical commercial values. Recent years saw wider adoptions of T-foils on high-speed ships, which greatly improve ship performances in waves. In this study, we designed a series of model tests to study the motion-reducing effects of T-foils in waves. Heaves, pitches, and bow accelerations are quantities to be measured in the experimental tests. The study shows that the reduction effects of T-foil-controlled longitudinal motions of a trimaran model are prominent. Comparing with naked model tests, it is found that active T-foil controls may reduce motions of trimaran ships in irregular waves by about 20-30%. In the most favorable case, the reduction is as high as 51%. This study shows that installation of T-foils may dramatically reduce the motions and, thus, provide an efficient control tool to mitigate ship motions in waves. The main aims of the present study were to provide an experimental setup for model testing of an active T-foil control system and determine the control equations. Although the control and actuation systems designed in this study are simple, they do produce the required effects. The model-tested control equations can be used for high-speed foil-type ship design directly if proper similarity ratios are used to project the model test results to real ships.