Dynamic Analysis of Geared Rotors-A Review
Rotor dynamics plays an important role in many engineering fields such as gas turbine, steam turbine, reciprocating and centrifugal compressors, the spindle of machine tools, and so on. Owing to the growing demands for high power, high speed, and light weight of the rotor-bearing system, computations of critical speeds and steady-state response at synchronous and sub critical resonances become essential for system design, identification, diagnosis, and control. The present paper reviews some of the approaches that have been developed to provide a means for understanding and simulations of the characteristics of a geared rotor dynamic system. More emphasis is given on the lateral vibrations of the rotors, effect of coupling of torsional and lateral vibration of rotors especially when the rotors are coupled with gears. Keywords—Critical speed, Geared rotors, Lateral vibrations, Rotor dynamics, Torsional vibrations.
Dynamic Analysis of Integrally Geared Compressors with Varying Workloads
Integrally geared compressors are characterized by compact and high efficiency machines, which are widely used in modern processing industries. As an important part of integrally geared compressors, a geared rotor-bearing system exhibits complicated dynamic behaviors. When running at rated speeds, a coupling system likely produces resonance with an adjusted workload, and a critical load phenomenon occurs. The dynamic coefficients of bearings, axial force and torque, and gear meshing stiffness vary with workload because of the interaction between rotors. In this study, a dynamic model of a geared rotor-bearing system influenced by the dynamic coefficients of bearings, axial force and torque, and gear meshing stiffness is developed. The dynamic responses of the coupling system are calculated and analyzed by using a typical five-shaft integrally geared compressor as an example. The effects of different parameters on the dynamic behaviors of the proposed system are also considered in the discussion. The geared rotor-bearing system is further investigated to examine the failure mechanism of the critical load.
Whirl Speeds and Unbalance Response of Multibearing Rotors Using Finite Elements
Analyse, par une methode des elements finis, du comportement dynamique d'un rotor a parametres repartis, portant des disques rigides et monte sur plusieurs paliers. Les equations matricielles et differentielles lineaires du premier ordre qui representent l'element de rotor et le systeme tout entier tiennent compte de l'inertie de rotation, du moment gyroscopique, de la charge axiale, des deformations de cisaillement transversal et des amortissements internes visqueux et hysteretique. Apercu des methodes employees pour la resolution de l'equation aux valeurs propres et pour le calcul de la reponse a un balourd. Discussion de l'influence du cisaillement et de l'amortissement sur la stabilite, les vitesses critiques et cette reponse, d'apres les resultats d'applications numeriques