| The 21th century has been called as the century of the ocean. In order to develop the ocean exploration, exploitation, transportation and costal defense, it is necessary to speed up the development of high-speed and high-performance ships. As one kind of new concept ships, trimaran attracts more and more attentions because of its excellent performance. Several practical trimarans have been built in recent years, based on experimental and theoretical researches in many countries. The flow field around the Trimaran becomes more complicated due to the existence of side hulls, and the hydrodynamics of trimaran has been changed considerably. It has been the research hotspot for many scholars around the world to accurately simulate the flow field, optimize the configuration of trimaran, improve its hydrodynamic performance.First the author in this paper investigates the feasibility of FLUENT in calculating the resistance of trimaran. By comparison with the experimental data he found that it could be used as a tool for optimizing the configuration of trimaran, because of its accuracy especially in the low speed section. Then the differences were analyzed and compared between five common turbulence models by simulating the trimaran "FA-2". The results showed that the k-ωmodels can give a better resistance prediction than the k-smodels. All the models except RNG k-εcould successfully predict the significant wave interference among three bodies.To avoid the long time calculation of CFD, the author deduced the Michell integral formulas and compiled program for trimaran wave making resistance. By comparison with the experimental data it was found that it could be used as a approximate tool for optimizing the trimaran's configuration. It can reflect the relationship between the configuration of trimaran and its resistance, even though the accuracy is not high. Then based on this theory, a program was made to optimize the trimaran's configuration.Finally, nine configurations of trimaran were choosing to analyze the relationship between the resistance, flow field details and trimaran's configurations. The results shows that by suitably locate the longitudinal and transverse position of the sidehulls relative to the centerhull, the resistance can be reduced, and the best locations are different for different speeds of the ship:It is better to set the side hull ahead at the low speed, but back at the high speed. By analyzing the relationship between the turbulence intensity and both the resistance and lift, it was found that the relationship between turbulence intensity and resistance is of inverse relation:The higher the turbulence the lower of resistance. The relationship between turbulence and lift is complicate. |
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