Design And Experimental Study Of Active Anti-rolling System For Ships Based On Propeller

Ships sailing in the ocean waves will have six degrees of freedom of movement such as rolling,swaying,pitching,pitching,swaying and swaying,when affected by wind,waves,currents and other factors.If the movements of the ship are not properly controlled,it may lead to disastrous consequence,endangering the normal performance of ship and the safety of the personnel inside ship.Among all these movements,the most severe is rolling motion.Therefore,it is becoming increasingly hot to find out how to reduce the occurrence of this phenomenon in the field of ship motion control.This paper proposes a new type of active anti-rolling method applied to ship based on the propeller thrust.The rolling model of the target ship is established by simulation analysis and the anti-rolling performance of the anti-rolling system is verified.The anti-rolling test is carried out based on the finite element strength analysis of the whole "real ship-anti-rolling device".The anti-rolling effect of the anti-rolling system is verified in practice,and the reliability of the anti-rolling device and the safety of the test are guaranteed.After experimental analysis,it is found that it has a good effect.The main work is as follows:(1)the rolling analysis of four-level sea conditions and anti-rolling effect simulation are carried out.It is a prerequisite to learn the ship's seakeeping theory for understanding the law of the ship's roll motion in the waves.Therefore,this paper studies the ship's seakeeping theory,analyzes the mechanics of the ship's roll motion.The work is as follows:Ocean environment is established and the appropriate wave spectrum is selected for wave energy spectrum calculation.The codes for wave inclination are written in Matlab and the simulation results in the wave inclination curve at different encounter angles are obtained.Finally,the rolling simulation curve of the ship can be obtained and the accuracy of the control system algorithm can be verified.(2)the design and strength calculation of active anti-rolling device are carried out.Two sets of anti-rolling devices were designed,one for the wooden ship model in the pool test and the other for the actual ship in the sea test.For the wooden ship model,the mechanical strength of the key components of the anti-rolling device is checked.And in order to ensure the safety of the sea test and the mechanical strength of the connection between the anti-rolling device and the real ship,this paper carries out finite element strength calculation analysis on the whole "real ship-anti-rolling device”based on the principle of equivalent design wave and the stress nephogram of the whole"real ship-anti-rolling device" under five extreme sea wave conditions is obtained.(3)the performance of anti-rolling device and the verification of anti-rolling effect are tested.The anti-rolling device needs to be tested to verify its reliability and practicability.So the pool test and the sea test were carried out.For the pool test the ef'ficiency of the anti-rolling device under the zero-speed rule of the ship is verified,proving that efficiency can reach about 80%under this condition;for the sea test,the test shows that the anti-rolling efficiency under this condition is about 50% at 0-5 kn.speed.