Study On The Rolling Motion Of Ship Under The Effect Of Wind,Current And Random Wave

With the revision and perfection of IMO’s 2^nd-generation intact stability code,the phenomenon of large-amplitude rolling of container ships is attracting attention.The periodic variation of wet surface and restoring stiffness of ships forms parametric excitation.When the ship-wave encounter frequency satisfies parametric vibration condition,and when high wave height meets small damping,ship may responds to parametric vibration.Especially in real sea conditions,random wave coexists with wind load and current load,making the ship’s roll response more intense,so it is necessary to study anti-roll measures.In this paper,AQWA hydrodynamic software is used to study the rolling of ultra-large container ships in random waves.Firstly,the numerical simulation method is determined and the rolling damping is calculated.By comparing the numerical calculation of C11 container ship with the model test results,the calculation method and simulation settings adopted in this paper are verified.Based on verifying the correctness of the calculation results,the wave spectrum and environmental parameters used in the numerical calculation are determined.The main object of this paper is an ultra-large container ship,which has many advantages and good prospects for future development.In this paper,the rolling response characteristics of ultra-large container ships under multiple waves are respectively analyzed from the angle of rolling response amplitude and response frequency,and dangerous navigation conditions are indicated.Based on the study of multi-wave direction rolling in random waves,this paper calculates the steady wind load and current loads by using Fujiwara’s component-separated wind calculation method,and determines the current laod referring to CCS regulation.The input wind speed and current speed is determined via previously calculated sea conditions,and four groups of wind and current directions are chosen.The corresponding effects of wind,wave and current on the random roll response of ultra-large container ships is studied.Finally,in view of the various navigation conditions of the ultra-large container ship,bilge keel and fin-stabilizer are added respectively.The effect of anti-rolling measures in the presence of wind and current loads in different directions and in the presence of single random wave is studied from the angle of roll response amplitude and frequency as well.This paper considers the random rolling response of ultra-large container ships with wind,wave and current loads,and compares it with the case of sailing in random waves.In addition,the anti-roll measures of ultra-large container ships are studied,and the anti-roll effect is given,which makes the research of this paper possesses certain application value and referential significance.