Research On The Influence Of Propeller Hydrodynamic Force On The Dynamic Alignment Of Shafting

The rapid development of economic globalization has promoted the prosperity of the shipping industry,and the world’s strong demand for ships has led to the continuous development of ships in the direction of large-scale,which also puts forward higher requirements for the manufacturing level of the shipbuilding industry.One of the challenges brought by the large-scale ship is to put forward new requirements for the alignment of ship shafting.In recent years,stern bearing wear and even ablation accidents have occurred continuously.After investigation,it is found that the accidents are obviously more likely to occur for the huge ships with super large size propeller and the long shafting ships with high-speed propeller.The existing reasonable alignment calculation of shafting can not be done In order to meet the requirements,a more perfect alignment method must be carried out for such ships,so the research on dynamic alignment is gradually launched.The dynamic alignment technology is based on the reasonable alignment to consider the possible fluctuation of the bearing load under the dynamic condition of the ship.The pre adjustment of the bearing displacement makes the load of each bearing still within the allowable range when the ship is running.At present,there are three main factors considered in dynamic calibration: hull deformation,oil film stiffness and temperature,and propeller hydrodynamic force.This paper mainly studies the influence of propeller hydrodynamic force on the dynamic alignment of shafting in the process of ship operation.Because there is no laboratory capable of dynamic alignment experiment at home and abroad,there is little research in this field at this stage.With the rapid development of computer technology in recent years,using CFD(Computational Fluid Dynamics)simulation technology for dynamic alignment research has become a more feasible way.In this paper,three-dimensional modeling technology is used first,which is based on the two-dimensional model of propeller.The two-dimensional model coordinates of propeller are transformed into the coordinate values under the three-dimensional coordinate system by using functions.Based on SolidWorks,the three-dimensional model of Mau propeller is built,which is prepared for the introduction of CFD software into propeller for hydrodynamic analysis.Secondly,the hydrodynamic calculation of the propeller is carried out by using the fluid analysis software,and the three-dimensional model of the propeller is imported into the fluid simulation software star-ccm + for fluid analysis.The parameters of the propeller are changed in turn by using the control variable method,and the hydrodynamic data(propeller thrust and propeller radial force)of the propeller are extracted,and the screw is established according to the principle of least square method and the fitting function of data points The mathematical model of the influence of propeller parameters on the propeller hydrodynamic force provides a simple and accurate method for the following dynamic alignment calculation,which avoids the complex work of repeated 3D modeling and fluid simulation of propeller.Finally,the 3D model of the real ship shafting is built by SolidWorks,and the influence of the propeller hydrodynamic force on the load change of each bearing of the shafting is analyzed by using the finite element software ANSYS Workbench,and the suggestion of dynamic alignment(adjusting the vertical displacement of the bearing)based on the reasonable alignment is put forward,which provides the reference for the later dynamic alignment calculation of the shafting.The influence of rudder angle on the horizontal load of stern bearing is studied...