Numerical Study on Seakeeping Performance of Hydrofoil Assisted Submersible Trimaran (HAST)

Abstract

The present study focuses on the seakeeping characteristics of Hydrofoil Assisted Submersible Trimaran (HAST). The seakeeping performance is an important part in ship design because it effects the comfort, control, resistance and safety. The motions in wave will reduce the performance of ship which is designed and optimized in calm water. The heave and pitch motions of HAST in calm water and regular waves have been investigated by STAR CCM+, a CFD analysis program. The theory of numerical simulation based on STAR CCM+ has been presented. The basic theory of seakeeping performance studies has been discussed. A series of simulations have been undertaken using STAR-CCM+ for various speed regime. The simulation setting is presented in this thesis. Overset mesh is applied to increase the accuracy and efficiency of numerical simulation. In addition simulation data of a trimaran of similar dimensions has been used for comparative analysis. The mean value of trim angle, sinkage in each working conditions are given in this thesis. The oscillation amplitude of heave and pitch is also collected and shown to describe the seakeeping performance of HAST. The hypothesis was that a non-conventional hull form such as HAST would provide reasonably better seakeeping performance than a traditional trimaran hull form. The result indicated so far shows that HAST has better heave response when compared against a traditional trimaran hull form at high-speed. However, the pitch response of HAST appears to be a lot worse than a traditional trimaran.