The Research About Theoretical Method And Prediction Of Maneuverability Of Trimaran

Compared with normal ships, trimaran witch is high performance ship has many advantages. It is good in resistance, seakeeping performance, stability, deck capacious,flexible layout, strong survival ability because of the protection of the outrigger and etc., so trimaran is widely used in both military and civilian. The high speed trimaran used more water jet propulsion and though each of three hull is thin, trimaran has a certain distance between main body and the two outrigger, which lead to the large total width of a trimaran.Due to all above, trimaran has unique characteristics in ship maneuvering performance. In addition,different locations of outrigger have a great influence on maneuverability of trimaran. Moreover,maneuverability is importantly related with the safety of a ship,so the study of maneuverability is necessary. At present, as maneuverability of trimaran is going to unceasingly mature stage,it is not recognized in many aspects. In a nutshell,the research of trimaran maneuverability faces the certain difficulties but is also significant and urgent.In this paper, CFD is used to simulate the viscous flow field in maneuvering motion of trimaran. Based on MMG model, hydrodynamic forces and moments are obtained through simulating of oblique towing test, no drift angle rotating arm test and rotating arm test with drift angle. In this study, third order and coupling hydrodynamic derivatives are got.Moreover, based on third order derivatives, maneuvering motion differential equation is founded in this paper. According to the derivatives got on the simulation, maneuverability is predicted. In order to study the outrigger affection of trimaran maneuverability, 6 kinds of layout scheme which include different longitudinal and transverse position have being calculated to find out which scheme is well.The research in this paper shows that the method of maneuverability evaluating is accuracy and reliable based on the verification of experiment and data. The study of outrigger of trimaran shows that forwarder longitudinal location can improve turning performance as well as smaller side span of outrigger can also improve trimaran turning performance.