High Speed Trimaran’s Pitch Reduction Method Research

Because of quickness,stability and excellent large deck area,high speed trimaran became a research hot-spot now.High-speed trimaran has such a superior performance because of its special structure of slender,but this slender structure also make the hull longitudinal shake violently in high speed and restrict trimaran’s wide application.Therefore,how to reduce the trimaran longitudinal shake and make the longitudinal motion stability in high speed has become the main research areas.This article use T-foil and Flaps as the mechanical stabilizer as the method and discuss the longitude damping effect at the autonomous stabilizer or control method with T-foil and Flaps.Firstly,establish 3D model of trimaran,T-foil and Flaps using CAD and get the different sizes experimental simulation model.Design experiments according both vertical anti-rolling possessed size and location using ANSYS 16.0 workbench and FLUENT of CFD to divide grid and solving lifts,drag,lift coefficient and drag coefficient.Using parameterized management methods to analyze different parameters of stabilizer and finally choose T-foil and Flaps with the best damping effect.To discuss different anti-rolling damping effect before and after installation,using ANSYS AQWA to analyze dynamic characteristics of the water and get the rules under the action of waves and irregular waves of different conditions on hydrodynamic coefficients of trimaran.For rule waves directly into sinusoidal input,using AQWA to analyze water hydrodynamic coefficients under different speed between fixed frequency range;for irregular waves needs to using random wave theory to establish a mathematical model of random waves,then input it into the MATLAB simulation system and get the heaving and pitching value after analyze control system to improve the damping effect of vertical stabilizer.In addition to design stabilizing appendage,after decided the best stabilizing appendage dimensions and installation location,in order to achieve better damping effect,this paper use sliding mode control based on reaching law and fuzzy control to control the angle of incident flow of T-foil and Flaps then control the longitudinal motion of the hull of the ship.Sliding mode control has the better robustness and fuzzy control is easy to establish and has the better anti-interference ability,faster response speed and has no need to create a controlled object accurate analysis mechanism model.The results showed that the two methods can both well restrain trimaran longitudinal shake,but the method of sliding mode variable structure control effect is better than fuzzy control.