Study On The Nonlinear Dynamic Problems Of Rotor-seal-bearing System Based On Hamilton Principle

Steam turbine-generating unit is the original motive and the key link of energy production. With the development in science and technology, the capacity of steam turbine-generator unit, as well as the operating parameters is continuously increasing, and toward the direction of high-speed, multi-span and heavy loads. Since the steam turbine rotor structures are getting more complicated, many nonlinear factors have become the hidden danger of the safe operation of generating units. So people have raised higher requirements toward the reliability, security and stability of the units.In recent years, in order to raise the energy efficiency, China's ultra-supercritical and large-scale nuclear power steam turbine group are increasing rapidly, and the problem of steam excited vibration are being much accounted of. For the purpose of ensuring the safe operation of generating units, home and abroad have also taken various measures to improve the structures of the seal, but effective theoretical researches and guidance are still lacking. Since most of the researches, which are in the field of rotor dynamics, haven't thoroughly considered the effect of non-linear incentive. There exist some limitations.This paper, on the basis of getting familiar with turbine steam structure and analyzing the cause of the steam excited vibration-induced accident, constructed a simple single-disc single-spam turbine rotor model. While taking into account the effect rotor bending, shear effect and eccentricity, the author has comprehensively considered the effect of nonlinear seal force and bearing oil-film force, at the same time, applied Hamilton principle, combined the finite element method, and derived the nonlinear dynamic model of rotor-seal-bearing system. By numerical analysis, this paper obtained the periodic response. According to the system's bifurcation diagram, time history diagram, Poincare map, frequency spectrum, phase trajectory maps, the author has investigated the nonlinear dynamic characteristic of rotor-seal-bearing system in some specific rotation speeds, seal structures and steam parameters.When modeling, this paper has taken the combined effects of several nonlinear factors into account, which is closer to the actual operation condition of the steam turbine and with better representativeness. All these have laid a better theoretical basis for the research of the elimination of steam excited vibration and improvement of systematic stability.