The Research On Hydrodynamic Characteristics And Anti-pitching Performance Of Trimaran's T-foil

With the development of the shipbuilding industry and technological upgrading,people's demand for high performance ships has been increasing and research has become more and more in-depth.Among them,Because of the advantages of high speed,good sea-keeping,spacious deck and strong survival ability,trimaran has developed rapidly and has received wide attention.The research on the trimaran has shown that the ship's rocking motion can not be ignored when trimaran navigating in wave that it's wavelength is close to the peak of the ship's motion response curve.Roll motion can be reduced by using bilge keel or anti-rolling fins,but there are little researches of anti-pitching appendixes.In this paper,based on the theory of viscous flow,CFD technology is used to simulate the movement of the trimaran in the regular waves,and the response characteristics of the trimaran are predicted and discussed.The VOF multiphase interaction model and the cavitation model are used to predict the T-foil's cavitation phenomenon,an effective theoretical forecast method is given.The result of simulation with or without cavitation model are compared.The responses of the trimaran with T-foil in head regular waves are predicted and analyzed.The influence of different installation angles of attack is studied.The characteristics of cavitation phenomenon of T-foil under different angles of attack are studied.The results show that the T-foil has better effect in reducing the hull's pitch motion.At high speed,T-foil will occur cavitation phenomenon,CFD prediction of T-foil's mechanics characters,regardless of cavitation,will be bigger than the actual data.Predicting hull's response characteristics according to the results of numerical simulation,will exaggerate the T-foil's anti-pitching performance.The anti-pitching performance of T-foil is different in different waves:in the wave with short wavelength,the longitudinal motion performance of the trimaran is obviously improved,the response peak is significantly reduced,the hull movement response is more stable.In the wave with long wavelength,T-foil will slightly increase the hull movement response.The installment of T-foil will make the total resistance and additional resistance in waves larger.The increase of angle of attack will greatly change T-foil's mechanics characters,slightly improve T-foil's anti-pitching performance.T-foil willincrease the total resistance of the ship,but it will reduce the additional resistance in waves.