Numerical Simulation And Experimental Study On Motion Responses Of Lanjiang Crane Vessel Coupling System In Heading Waves

The movement of the block during lifting is affected by various environmental factors.To study the motion law of the block and provide guidance for lifting operations on mooring cranes,the MOSES software is used to analyze the sensitivity of the motion of the hoist system in heading waves.It is the first time that we use numerical simulation combined with model experiment to study the coupled motion law of the hoisting system of the Lanjiang crane vessel moored in heading waves in China.Firstly,through the model test of the pond,the free-attenuation motion of the Lanjiang mooring crane lifting system in still water was studied.Experiments were conducted on the coupled motion response in regular waves and irregular waves simultaneously affected different wave directions,different wave periods,and the weight of different hanging objects and different lifting heights.Secondly,based on the three-dimensional potential theory in the frequency domain and the coupled equations of motion of the mooring cranes,a numerical simulation method was used to analyze the kinematic characteristics of the suspended mooring vessels in the heading waves and compared with the model test movement RAO results in the regular waves and Statistical results in irregular waves.Finally,the numerical simulation method was used to study the susceptibility of the lifting system to the wave period,wave height,weight of the lifting block,and height of the lifting height.At the same time,the applicability of the hoisting of 1000 t,2000t,and 3000 t blocks of Lanjiang mooring crane vessel was analyzed with China's coastal environment under Nobel Denton's operation specification for floating cranes.The model test and numerical simulation results show :(1)The surge of the block is the coupling motion between the surge of ship,the wave action and the swing of the hoist itself.When the wave period is close to the swing period of the block,the resonance phenomenon occurs in the swing motion of the block,and the amplitude of the motion is maximum.(2)The heave motion of the block emerges as a coupling motion between the ship pitching and the wave excitation.When the wave period approaches the ship pitching cycle,the heave motion of the block shows a maximum value.The analysis shows that the tension of the mooring cable is expressed as the coupling between the ship surge,the ship pitching and the wave excitation,and the strength of the mooring cable on the front wave side is larger than that of the smooth waves.The results of numerical simulation methods for the analysis of wave period,wave height,and weight of hanging objects and lifting height sensitivity show that :(1)The sensitivity of block's surge motion and heave motion to wave height and wave period will change with the increase of the peak period of the irregular wave.The surge motion of the block is sensitive to the change of wave height when the irregular wave period is low,however,the swaying movement of the block is sensitive to the change of wave period when grows higher;The block's heave movement is sensitive to wave period variation when is low and sensitive to wave height change when changes higher.(2)The amplitudes of the surging and heaving movements of the blocks increased with the weight of the blocks,and the increase of the swaying movement was more obvious than that of the heave.(3)The higher lifting height of the block,the larger amplitude of the surge motion of the block and the smaller the amplitude of the heave motion.Therefore,when the lifting height of the block is changed,the height should be adjusted reasonably to avoid the resonance period between the wave and the swing block.According to the analysis of the suitability of the Lanjiang crane vessel in heading waves,it is found that there are many applicable sea conditions when the wave period is small,and when the wave period is relatively large,the applicable sea state decreases sharply.Long-period waves have a significant influence on the applicability of mooring cranes.The applicability analysis of the Lanjiang crane vessel in this paper can provide reference for its actual hoisting construction.