| Powering performance, as one of the most basic perfromance indices, has always played a significant role in ship design. For a small to medium size surface craft, the creation of a air bubble beneath its bottom by means of ventilation will not only reduce its frictional drag, but also make it more comfortable. The performance of a artifical ventilated deep-V planing boat with two degrees of freedom in pitch and heave was numerically studied under both still and wavy water conditions.The resistance and attitude under still water of a nonventilated boat was calculated firstly to make comparison with those derived from Ts GAI and SIT methods. The result proved the numerical method to be authentic and was used as a key reference for gas chamber design. The gas chamber was design ed based on the princples of stepping boats. The conections between Froude number, attitude, air cavity pattern, and drag reduction rate of the ventilated boat was then studied.The drag reduction rate of the ventelated boat was further investigated under wavy conditions in a numerical wave tank. A comparison was made under still and wavy water conditions about attitude and drag. Followed by a investigation about the influence of wave on attitude, air cavity form, drag reduction rate,and dynamic response of the boat. |
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