The Nonlinear Analysis Of Rotor Dynamics With Segment Shoe Bearings

The quality of the vibration state of turbocompressor units is significantly affected by two main factors including the reduction of driving forces and the critical frequencies detuning of rotation operation. During the entire range of rotation frequencies, the balancing degree of quality rotor is one of the important criteria that measure whether the turbocompressor can work reliably or not. Generally, such a balancing degree depends on the balancing frame, the balancing weight systems, and the choice of stiffness and resistance coefficients of rotor systems. On the other hand, the critical frequencies of rotors are primarily influenced by the dynamic characteristics of segmental bearings. In this thesis, we considered the nonlinear dynamics of turbo-compressor and the obtained results shows that the estimated reliable values of stiffness and damping coefficients can make the prediction for the rotor performance of high-speed turbo-compressor unit be more accurate.(1) A set of effective methods are developed to estimate the parameters of mathematical models of rotor systems and the program to obtain the values of stiffness and damping coefficients of bearings based on the experimental data accumulated in the process of balancing rotors on the HSBS.(2) The impact of internal resistance of the horizontal rotor on the parameters of its synchronous precession has been mathematically revealed, meanwhile, the method to estimate this impact has been proposed by introducing an equivalent external damping in the central part of the rotor.(3) The obtained results show that as the rotation frequency increased, the stiffness of bearing increased but the resistance of bearing decreased.By employing the proposed methods, we can obtain reliable value of the stiffness and resistance coefficients of rotor systems. These obtained parameters not only set the basis for the design of turbocompressors but also provide a way to accurate predict its performance.