Research On Dynamic Shafting Alignment Considering Oil Film Characteristics Of Aft Stern Tube Bearing

Propulsion shafting undertakes complex stresses and loads in normal operation as an important part of marine power equipments. Therefore, shafting alignment quality plays a great role in protecting safety and reliability of shafting operation. In this thesis, oil film characteristics of aft stern tube bearing are studied and analyzed based on rational shafting alignment calculation. Then the method of dynamic shafting alignment considering oil film characteristics of aft stern tube bearing is realized.Rational shafting alignment is the foundation of dynamic shafting alignment. In this thesis, equivalent physical model of the shafting is constructed based on the theory of Finite Element Method, and the method of rational shafting alignment calculation is designed. Then a rational shafting alignment calculation program is developed by Visual C++language. Compared with some rational shafting alignment calculation examples, The feasibility and validity of the alignment calculation is proved. It's the foundation for dynamic shafting alignment research.Oil film characteristics of aft stern tube bearing is more complex than all other bearings because journal is oblique due to propeller cantilever action. In this thesis, according to the theory of journal bearing with hydrodynamic lubrication, the method for lubrication parameters calculation of journal bearing is designed combined with aft stern tube bearing. A program for lubrication parameters calculation is developed by Visual C++language. Then different parameters influences for dimensionless oil film pressure distribution and magnitude are analyzed. It's the foundation for dynamic shafting alignment research and calculation considering oil film characteristics of aft stern tube bearing.Oil film characteristics of aft stern tube bearing is an important dynamic factor for dynamic shafting alignment. In this thesis, according to improved model of the shafting, dynamic shafting alignment calculation considering oil film characteristics of aft stern tube bearing is achieved based on equivalent displacement method. Taking 76000 dwt crude oil tanker as an example, an program for dynamic shafting alignment calculation considering oil film characteristics of aft stern tube bearing is developed and verified by Visual C++ language, and the results reveal aft stern tube bearing and intermediate bearing loads increase, fore stern tube bearing load decrease, the other bearings loads almost no change considering oil film characteristics of aft stern tube bearing. Then appropriate results are getted by alignment calculation considering oil film characteristics of aft stern tube bearing.