Research On The Nonlinear Dynamic Characteristics Of A Rotor-Bearing-Seal System

Rotating machinery is one of the most important equipment in national foundation establishment and industry, and plays a nonreplaceable role in many important fields of the industry. A lot of high requirements for stability, load, reliability and automation to turbomachinery have been made alone with the development of high speed, heavy load and efficiency. So its steam flow excitation force is becoming increasingly important. According to the currently accepted concepts of research results, it has been carried on from three aspects: seal exciting force, tip exciting force, static steam power acting on the rotor. And the study of seal forces is far less common and in-depth than that of fluid film lubricated bearings, so there is the widespread concern.Firstly, the paper introduces several seal force models, and describes the main characteristics of seal forces in Muszynska model; The nonlinear dynamic systems model of a Jeffcott balanced rotor and seals which is simple supported at its two ends is established with Muszynska model. The stability of the balanced rotor systems was analyzed with Lyapunov stable theory, advancing the critical speed formula of the balanced rotor systems; The influence of several parameters in the rotor system is researched with numerical simulation.Secondly, the nonlinear dynamic model of the unbalanced rotor systems is established, and the shooting methods and Floquet theory are applied to study stabilities and dynamic behaviors of the periodic solutions in the systems; The dynamic characteristics of systems at the certain rotating speed and the certain physic parameters are analyzed by the periodical responses, Poincarémaps, frequency spectrums chart, bifurcation charts, etc; Rising and falling the rotor speed , there is the delay located near bifurcation point of the systems through computer simulation ,.Lastly, considered the rotor disk which was supported by the bearings at the two ends, the complex nonlinear dynamic system model of the rotor-bearing-seal system is established with oil film forces of Capone circular bearings model. The dynamic characteristics of the systems at the certain rotating speed and the certain physic parameters is comprehensive analyzed by the periodical responses, Poincarémaps, frequency spectrums chart, bifurcation charts, etc; The comparison bifurcation charts with different parameters of the systems analyses nonlinear dynamic characteristics of the systems and researches influence to the whole system with the parameters of the rotor and journal.