Numerical study on the aerodynamic and hydrodynamic performances of an ultra-high-speed AAMV

In order to investigate the resistance performance of an ultra-high-speed aerodynamically alleviated marine vehicle(AAMV),finite volume method(FVM)-based computational fluid dynamics(CFD)software STAR CCM+is used to simulate the forward motion of this vehicle.The calculated results are validated as they reach good agreement with experimental data.Comparing the motions of models with and without aero-wings,the hybrid aerodynamic and hydrodynamic mechanism of this novel hull is discussed.Study is subsequently performed that how step configuration,spray rail and deadrise angle act on hull behavior and resistance.The results show that models with double steps and spray rail possess better resistance characteristics at high speeds,and planing surface with variable deadrise angle could further improve the overall navigation performance.

An integrated optimization design of a fishing ship hullform at different speeds

This paper shows how to improve the hydrodynamics performance of a ship by solving a shape optimization design problem at different speeds using the simulation-based design(SBD) technique. The SBD technique is implemented by integrating the advanced CFD codes, the global optimization algorithms and the geometry modification methods, which offers a new way for the hullform optimization design and the configuration innovation. The multiple speed integrated optimization for the hullform design is a challenge. In this paper, an example of the technique application for a fishing ship hullform optimization at different speeds is demonstrated. In this optimization process, the free-form deformation method is applied to automatically modify the geometry of the ship, and the multi-objective particle swarm optimization(MOPSO) algorithm is adopted for exploring the design space. Two objective functions, the total resistances at two different speeds(12 kn and 14 kn) are assessed by the RANS solvers. The optimization results show that the decrease of the total resistance is significant after the optimization at the two speeds, with a reduction of 5.0% and 11.2%, respectively. Finally, dedicated experimental validations for the design model and the optimized model are carried out for the computation and the optimization processes. At the two speeds, the reduction of the total resistance in the model scale is about 6.0% and 11.8% after the optimization. It is a valuable result in view of the small modifications allowed and the good initial performances of the original model. The given practical example demonstrates the feasibility and the superiority of the proposed SBD technique for the multiple speed integrated optimization.