Simulation And Experimental Study Of Shaft Mechanical Power Transfer Efficiency

With the emergence of large ships such as ultra-large oil tankers and giant oil tankers,the propulsion shafting of ships is also developing towards long shafting to meet the transmission requirements.Long shaft systems are often more than 100 meters long and have 10 to 30 supporting bearings,with a wide range of power equipment.A large amount of power loss is often accompanied by long shaft system operation.By studying the power transfer efficiency of ship shafting,the power loss of shafting in the transmission process can be reduced.At the same time,the shaft power transfer efficiency can also reflect the running state of the ship shafting and evaluate the shafting alignment quality,which is of great significance to the ship.At present,the research on each component of the ship shafting is developing rapidly,but there is no comprehensive study on each component of the shafting.This paper presents a dynamic alignment method based on joint simulation.Based on the static alignment of shafting,this method comprehensively considers the dynamic state of bearing lubrication film,external dynamic force and torque,and shafting bearing displacement under the operation of ship shafting.the shafting alignment and the main equipment of the shafting are comprehensively modeled,and the comprehensive influence of shafting design and working condition parameters on the transmission efficiency,alignment and vibration of the shafting is discussed.The correctness of the shafting power transfer analysis scheme is verified through the bench simulation test of shafting power consumption.The main research contents and conclusions are as follows :(1)A shafting dynamic alignment method based on Simulation X and MATLAB co-simulation is proposed.The visualization model of the whole shafting is constructed based on Simulaiton X,which can change and test the relevant data of the shafting more intuitively and improve the efficiency of modeling and analysis when studying the shafting alignment problem.This method combines the advantages of more accurate multi-body dynamics analysis and calculation,and adopts the method based on multibody dynamics to calculate the stress state of each support of the shafting.By combining the bearing analysis module based on MATLAB,the lubrication film of the bearing under the overall and dynamic state of the shafting is comprehensively considered,so as to realize the simulation analysis of the dynamic alignment of the shafting.The load of bearings of the same type of shafting calculated by this method is more balanced,which is more accurate than that calculated by the three-moment method,and solves the problem that the error of shafting alignment using transfer matrix method is too large in the face of super large shafting,which provides a new idea for the research of shafting alignment.(2)By modeling the main power consumption equipment of shaft system(underwater shaft system and disc seal),and by finite element analysis method,the influence characteristics of the main components of the shaft system on their power consumption are calculated.The multivariate factors are coupled by mathematical induction method,and the power consumption formula of the main components of the shafting is derived and fitted.The shaft power transfer efficiency is analyzed based on the power consumption of each component.(3)The influence of various shafting factors on the power transfer efficiency and static and dynamic characteristics of the shafting is analyzed.The following conclusions are obtained by calculation : the shaft diameter of the stern shaft has a great influence on the shafting alignment,shafting vibration and shafting power transfer efficiency.With the change of stern shaft span,the dynamic stiffness and dynamic damping of each bearing change greatly due to the load change at each bearing position,which has an impact on the vibration response results.However,due to the unchanged basic structure,it has little effect on power consumption.The length-diameter ratio of1 # intermediate bearing has a great influence on the power consumption of the shafting.Through the above analysis,stern shaft diameter,stern shaft tube bearing span,1 #intermediate bearing length-diameter ratio are the major design factors.(4)Through the power transfer efficiency test of shafting,the shafting speed,bearing elevation and propeller simulation excitation are taken as design variables.The correctness of the shaft mechanical power transfer matching model is verified by the experimental part.