The Theoretical And Application Study Of The Propulsion Shafting Alignment Under Dynamic Factor

Marine shaft alignment is a very important step during the shafting designing and its assembling, and also assure the shaft’s normal operation.The state of shaft alignment relate directly to the force of each bearing, concerned by all researcher. After decades of research at home and abroad, the method of shaft alignment has developed from Fair Curve Alignment Theory to Reasonable Alignment, and widely applied in the process of alignment.With the appearance of High-speed and Overload Vessel, people are paying more and more attention on the dynamic alignment. Against this background and based current research, the thesis mainly completes the following areas:(1) A review in detail is given of the alignment theory, including classification, modeling, computational methods,etc..In traditional shaft alignment, it always takes Aft stern tube bearing as single support, when actually the bearing force work in a length of bearing. Hence, the thesis takes Aft stern tube bearing as multiple support, and makes a theoretical derivation of bearing force on multiple support.(2) A40m crafttug shaft and a7060kW Multi-purpose vessel are studied as an example in this article. First, carry on finite element analysis of40m crafttug shaft using ANSYS. Then, compared the ANSYS result with three-moment method, and it illustrates the validity of multiple support alignment.(3) Position of support point in shaft alignment have a great effect on whirling vibration calculation. The essay take a7060kW Multi-purpose vessel as an example, it select different support point of Aft stern tube bearing, get whirling vibration calculation result. Then it compared the result when support point is multiple support, equivalent single support, experience value, etc..(4) Theory of sliding bearing’s hydrodynamic lubrication, computational methods of oil film pressure and dynamic characteristics of the oil film is introduced. The thesis analyse the relation among oil film pressure and shaft speed, slope angle. Also, the essay recounts numerical computation method of oil film pressure. Then, using MATLAB, gets oil-film pressure and the graphic demonstration. And it makes a discussion about alignment considering oil film pressure. In sum, the thesis make a theoretical derivation of bearing force on multiple support, compute the bearing force in multiple support model, discuss the influence of support point on whirling vibration calculation,analysis the oil film pressure using matlab in different shaft speed and alope angle, make a study about oil thickness on the necessity of bearing slope boring.