Research On Vibration Characteristics Of Ship Propulsion System Based On Universal Coupling

Ship propeller and propulsion shafting are the power base of ship operation,and the dynamic performance of propeller and shafting system will influence the stability of ship propulsion system.In the context of the rapid growth of technology and science,the working efficiency of ship propulsion system is more and more demanding,at the same time,the use of special mechanism also increases the complexity of shafting performance.The ship is in the process of design,the propulsion system and ship vibration need to be tightly controlled,moreover,when there is a height difference between the midpoint line of shafting and the midpoint line of main engine,the traditional layout of ship propulsion system has been unable to meet the demand,in addition,the design of the propulsion system needs to consider the vibration characteristics of the shafting in complex water environments to assure the security and reliability of its navigation.Therefore,this paper intends to use a special transmission mechanism with shafting angle,by building the system analytical model of the sub-mechanism,and MATLAB software has been used to simulate the influence of shafting angle change on its kinematic and torsional vibration characteristics,furthermore,the basic coupled vibration character of the propulsion structure were studied,and the way to decreace the shake of the propulsion structure was explored,then,the torsional vibration characteristics of propeller shaft structure under propeller hydrodynamic action were studied,the finite element model of universal shafting was simulated by adding propeller excitation force,and the project application was analyzed at last.The major inferences are presenting below:(1)Aiming at the problem of height difference between the center line of ship shafting and the center line of main engine,a special transmission mechanism was introduced,the system analytical model of the mechanism was built,and the influence of the change of propulsion shafting angle on its kinematic characteristics was analyzed,the effects of shafting angle alter on torsional vibration of shaft and vibration coupling caused by shaft and lateral forces of universal shafting were also studied.(2)According to propeller correlation type value data,3D modeling was established in SOLIDWORKS,and griding the computing domain in Iceam CFD,then the hydrodynamic simulation of propeller was carried out on ANSYS WORKBENCH platform to study the influence law of different parameters on propeller hydrodynamic force.(3)In order to study the torsional vibration characteristics of universal shafting under complex hydrodynamic characteristics,based on the fluid-structure coupling method,the propeller structure and the flow field are solved,and the finite element model of universal shafting was simulated by adding propeller excitation force;The least square way was applied to adapt the performance of the influence of the change of shafting angle on the twisting stiffness of the cross shaft caused by the propeller motivation force,a mathematical model of the affect of shafting angle on the twisting stiffness of the cross shaft was established.Based on the above research,the influence of shafting angle on the natural frequency of the universal coupling was further studied.(4)The torsional vibration problem of shafting under ice load excitation force was studied,and the model of shafting equivalent system with universal coupling was established.Firstly,the torsional vibration characteristics of propulsion shafting at different joints under ice-free loading were analyzed,then,the ice load was selected as a typical working condition for analysis,the influence of the angle change of propulsion shafting was considered to study the torsional vibration characteristics of shafting under the coupling effect of ice load and shaft angle.