Dynamic optimization analysis of a stored energy motor with serious unbalanced mass distribution
The rotor-bearing system of a stored energy motor, which is composed of exciter, main generator and asynchronous motor, has typical characteristics of serious unbalanced mass distribution. According to the rotor and bearing system of the stored energy motor, dynamic performance optimization analyses are carried out by means of the finite element analysis method, to give the system optimization method and to establish the system optimization plan.
Numerical Method and Bifurcation Analysis of Jeffcott Rotor System Supported in Gas Journal Bearings
From the viewpoint of nonlinear dynamics, the stability and bifurcation of the rotor dynamical system supported in gas bearings are investigated. First, the dynamical model of gas bearing-Jeffcott rotor system is given, and the finite element method is used to approach the unsteady Reynolds equation in order to obtain gas film forces. Then, the method for stability analysis of the unbalance response of the rotor system is developed in combination with the Newmark-based direct integral method and Floquet theory. Finally, a numerical example is presented, and the complex behaviors of the nonlinear dynamical system are simulated numerically, including the trajectory of the journal and phase portrait. In particular, the stabilities of the system's equilibrium position and unbalance responses are studied via the orbit diagram, phase space, Poincare mapping, bifurcation diagram, and power spectrum. The results show that the numerical method for solving the unsteady Reynolds equation is efficient, and there exist a rich variety of nonlinear phenomena in the system. The half-speed whirl encountered in practice is the result from Hopf bifurcation of equilibrium, and the numerical method presented is available for the stability and bifurcation analysis of the complicated gas film-rotor dynamic system.
A generalized solution of elasto-aerodynamic lubrication for aerodynamic compliant foil bearings
Although aerodynamic compliant foil bearings are successfully applied in a number of turbo-machineries, theoretical researches on the modeling, performance prediction of compliant foil bearings and the dynamic analysis of the related rotor system seem still far behind the experimental investigation because of structural complexity of the foil bearings. A generalized solution of the elasto-aerodynamic lubrication is presented in this paper by introducing both static and dynamic deformations of foils and solving gas-lubricated Reynolds equations with deformation equations simultaneously. The solution can be used for the calculation of dynamic stiffness and damping, as well as the prediction of static performances of foil bearings. Systematical theories and methods are also presented for the purpose of the prediction of dynamic behavior of a rotor system equipped with foil bearings.