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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 52760 (08)
- University: Sharif University of Technology
- Department: Mechanical Engineering
- Advisor(s): Sayyadi, Hassan; Karimi, Mohammad Hossein
- Abstract:
- One of the key issues in the design of vessels is their proper stability and performance in waves. Therefore, the use of twin-hull vessel designs such as conventional catamaran and SWATH is suitable for improving stability and seakeeping quality. Although SWATH has a better seakeeping quality than a conventional catamaran, it has been observed that at high forward speeds, especially in head waves, the vertical motions of the vessel is greatly enhanced. Various methods such as correction of the hull form and the use of fin stabilizers can be used to modify SWATH vessel motion behavior. These control surfaces can respond appropriately to the dynamic forces from the waves, reducing the motions in the waves and ultimately reducing the vertical accelerations caused by these motions, which nowadays are widely used in the marine industry.In the present study, with the aim of investigating the effect of control surfaces on the reduction of vertical motions of semi-SWATH vessel in the wave,at first, the added mass and damping hydrodynamic coefficients of a model of this vessel were obtained by using of CFD software STAR-CCM+ with verification. Then equations were presented to estimate the coupled heave and pitch motions in regular waves. Finally, by designing an optimal control system and applying the forces and moments caused by active fin stabilizers, the equations of motion in regular head wave conditions in the state-space were developed using MATLAB-Simulink software. The results indicate that the use of fin stabilizers can have a significant effect on reducing the vertical motion of this vessel in the waves
- Keywords:
- Seakeeping ; Hydrodynamic Coefficients ; Optimal Control ; Computational Fluid Dynamics (CFD) ; Increasing Stability ; Fin Stabilizers ; Semi-Small Waterplane Area Twin Hull (SWATH)Vessel
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