Research On Seakeeping Qualities Of Trimaran Based On Overset Grid Approach

Seakeeping directly affects vessels’operation capability and seaworthiness in severe sea conditions, which is an important indicator to judging the ships’ performance, especially for high-speed vessels. Because of the superior overall performance, trimaran has attracted researchers’ attention. It has a great significance to research and analyze the motion mechanism of trimaran in waves and improve its motion performance. In recent years, experimental and numerical research on trimaran seakeeping is increasing. But the application of viscous numerical method for computing is relatively few, which means it has certain academic and engineering value. In this paper, we use CFD method based on overlap grid technique. Under this condition, we could conduct numerical simulation of trimaran in regular wave and analyze its motion character in frequency domain.Firstly, this paper caculated motion response of trimaran model in regular wave. Compared the pitching and heaving calculation results with experimental value in the frequency domain, which showed the difference between heaving response amplitude calculation value and experimental value is below 20% in high speed, and the difference between pitching response amplitude calculation value and experimental value is below 20% respectively in low speed. Above verified that the CFD application in trimaran numerical simulation is reliable.Secondly, this paper research resonance motion of trimaran and observe obvious resonance phenomenon. Then we studied the difference of seakeeping between trimaran and the traditional ship type. The result implicated the seakeeping feature of trimaran has little difference with monohull under low speed. However, trimaran can effectively reduce the motion response amplitude under high speed, which verified trimaran can improve seakeeping quality under high speed. We caculated the motion response in different side body configurations of trimaran and compared the results in frequency domain. Also we researched the side body’s influence on seakeeping of trimaran in different velocities and analyzed the motion characteristics of different side body configuration in frequency domain.Finally, this paper use the orthogonal experiment method to optimize trimaran configuration based on seakeeping performance in regular head waves. Design-direct analysis and variance analysis are used to analyze simulation results. From analysis results, we get the seakeeping optimal configuration and the significative degree affected by location of side hull.