DYNAMIC RESPONSE OF A HYDRODYNAMIC THRUST BEARING-MOUNTED ROTOR

ABSTRACT For investigating the dynamic response of a hydrodynamic thrust bearing-mounted flexible rotor, the dynamic characteristic data of thrust bearings for high surface velocities are applied for constructing the equation of motion for the rotor system, which is modeled with the finite element method (FEM). Based on the short bearing approximation and the π film cavitation model of the nonlinear oil-film forces, the dynamic responses are investigated using direct numerical integration with a variable order solver based on the numerical differentiation formulas (NDFs). Harmonic, quasi-periodic and chaotic motions are predicted for a range of spin speeds of the rotor. Poincaré maps of predicted rotor trajectories are also examined. It shows that spin speeds of the rotor and the oil film force coefficient might promote undesirable non-synchronous vibrations

Optimization combines the genetic algorithms with augmented Lagrange multiplier method for rotor-bearing systems Copyright ©

ABSTRACT A new optimization strategy for the design of rotor-bearing system was investigated in this study. For most optimization methods applied to rotor-bearing system, it need to select a set of better initial values for design variables to get good results. This trial-and-error process is time consuming and even affects the results. To overcome this difficulty, Genetic Algorithms is applied to provide the set of initial values for design variables and Augmented Lagrange Multiplier Method is employed to determine the optimum results. Furthermore, the hybrid method is applied to minimize, individually or simultaneously, the weight of the shaft and the transmitted forces at the bearings. The results shows that the hybrid method can effectively search the better initial values set for design variables, and further, it can find the superior results to reduce both the shaft weight and the bearing transmitted forces under critical speed constraints