Numerical Research On Influence Of The Interceptor On Catamaran Hydrodynamic Performances

The 21th century is a century of ocean, human activities in ocean transportation, exploration and ocean energy exploitation appear much more intense and extensive, and which demand higher requirements to the improvement in ship hydrodynamic performances. When the medium and the smaller ships are travelling at high speed, the characteristics of flow field around and after stern affect the force acting on the ship and the power requirment. Under the conditions of that the main dimensions and the engine power are fixed, the method of improving the flow field around the ship, making the ship possess the best characteristics of resistance and motion, is one of the focuses. The stern interceptor is a kind of appendage newly developed in recent years, which, if well designed, is capable of improving the ship's hydrodynamics performance, the speedity and the maneuverability, which has a very good prospect in high speed vessels.Comparing with the ship body, the height of a interceptor is much smaller, thus, an effective scheme is needed to simulate the flow field, in order to compare the flow field with and without interceptor. Therefore, the CFD software FLUENT is used ,some calculations and investigations on the main factors that affect flow field are taken, including the method of grid generation, numerical method and turbulence model, some suitable set are suggested for the numerical simulation of catamaran with and without interceptor. Comparison of the numerical results with the experimental data validates the proposed method and applicability of the suggested set.There is a interaction between the interceptor and the vessel, as the first stage of the investigation of the interceptor's hydrodynamic mechanism, lowlization treatment is done near the stern, and simplifying first the real hull to a 2-D shiphull with flat bottom, ignoring the influence of transverse flow and curved form of the ship surface. Through the calculations of this 2-D ship with and without different height interceptors, the effect of the interceptor's influence is determined, then, in the condition with and without interceptor, the changing of speed and pressure is compared in the area considerably affected by the interceptor, the mechanism of the interceptor is investigated. Some discussions of the effects of changing the stern form on the hydrodynamic characteristics are also included.Base on these research, simulation of the 3-D catamaran model with and without interceptor are taken, calculation and comparison of the catamaran's hydrodynamic characteristics in the conditions with and without different height interceptors are included, and the comparisons of the numerical result of resistance and the experimental data show the effectiveness of the proposed calculation. The mechanism of the interceptor on the three dimensional ship is investigated; the effect of the interceptor to improve catamaran's hydrodynamic characteristics is shown.