Study On Motion And Added Resistance Of Ship With Hydrofoils Assisting Propulsion

In order to improve the propulsion and sea-keeping performance, aship with fixed wave devouring hydrofoils mounted at the bow is proposed.The motion response of ships can be efficiently reduced by using this shiphull, and the fixed wave devouring foils can extract wave energy togenerate thrust to reduce wave added resistance and assist ship propulsion.In this thesis, the CFD (Computational Fluid Dynamics) method andpotential theory are adopted to numerically investigate the hydrodynamicperformance of the oscillating hydrofoils and the effects of motionparameters of oscillating hydrofoils on the hydrodynamic performance.The motion response and wave added resistance in regular waves of acontainer ship with and without hydrofoils are investigated based onfrequency domain3D panel method, and a ship model test is also carriedout to validate the accuracy of the calculation. Finally, the effects of foilaspect ratio and amounting position are analyzed based on the numericalresults of three-dimensional panel method. The numerical results ofoscillating foils in uniform flow and waves show that foils with coupled heave and pitch motion or pure heave motion can extract energy fromwaves and uniform flow to generate thrust by selecting appropriate motionparameters, and that foils with only pitch motion cannot generate thrust butperiodic resistance. The experimental and numerical results of ship motionand added resistance show that the fixed wings contribute a lot to theimprovement of the ship sea-keeping performance. The pitch, heave andadded resistance in regular waves had been reduced significantly by thehydrofoils. And the motion and added resistance responses of the ship withhydrofoils are smaller than those of the prototype in the whole wavefrequencies involved. The peak value of heave and pitch response arereduced by21%and24%respectively, and the peak value of addedresistance response is reduced by almost80%. With the increase ofwingspan, the motion and added resistance responses of ship withhydrofoils decrease gradually. The propulsion efficiency of the foilsamounted and the bow is higher than foils amounted at mid-ship. Therefore，the motion and wave added resistance of a ship can be reduced efficientlyby optimizing the geometric parameters and amounting position of foils.