Numerical Simulation Of Dynamic Behaviors On The High-Speed Rotor System Supported By Gas Journal Bearings

The progress of science and technology has made the design of rotating machinery more high-speedly and efficiently. Simultaneously, higher requirements for dynamic characteristics, stability and reliability to the rotating machinery have been met with. With the development and application of the modern nonlinear dynamic theory, the research on rotor dynamics especially the behavior of high-speed rotor nonlinear dynamics takes a new visage after introducing the theory of modern nonlinear dynamics. Nowadays, it has been become one of the most popular research problems at home and abroad. Gas rotor bearings are new type bearings which make use of gas as moving lubricant.Comparing with other bearings, because there is only a little mucosity in gas,gas rotor bearings have so much virtues such as a bit of frition,no abrasion,no pollution,smooth operation,high rotate precision,precise maintenance of bearings and etc. These make gas rotor bearings more ascendant,more economical and more practical in high-speed rotating machines. Gas rotor bearings are more widely used in industries such as national defence,armory and dynamics.In this dissertation, researches are mainly objected to complicated dynamic behaviors of the systems of high-speed rigid rotor and flexible rotor supported by gas journal bearings through using nonlinear dynamics theories.The dissertation mainly contributes to the research in two points. Firstly, the model of dynamic bearing force on high-speed rigid rotor supported by gas journal bearings are established. Based on the non-dimensional form of the rotor system, the motion differential equation of the system is solved by using the Runge-kutta method. The diagrams of the system such as the phase diagrams, Poincare maps, spectrum analysis diagrams, bifurcation diagrams are plotted by methods of numerical simulations. The complex dynamic phenomena of periodic and chaotic motions are showed in the results. Secondly, according to the analysis above, the dynamical model of high-speed flexible rotor supported by gas journal bearings is similarly established. By the method of Runge-kutta, the motion differential equation of the system is solved. As a result, the diagrams of the system are plotted by methods of numerical simulations. The various forms of periodic and chaotic motions are showed in the results. Studying shows that there are dynamic phenomena such as doubling-period bifurcation, occasional chaotic motion through the special parameters in the systems and the parameters corresponding to the chaotic motion have fargoing range. Finally, the primary work of this text has been concluded, and the problem existed and the development trend of future work have been pointed out.