Establishment of Nonlinear Dynamic Model for Prediction of Rotordynamic Instability of Steam Turbine Rotor-Bearing System Caused by Partial Admission

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Ying Cui ◽  
Zhansheng Liu ◽  
Daren Yu ◽  
Yanfeng Duan
Keyword(s):  
Steam Turbine ◽  
Dynamic Model ◽  
Nonlinear Dynamic ◽  
Turbine Rotor ◽  
Nonlinear Dynamic Model ◽  
Steam Turbine Rotor ◽  
Rotor Bearing ◽  
Partial Admission ◽  
Bearing System

A nonlinear dynamic model is developed for a rotor-bearing system with radial steam force due to partial admission, taking into account the prediction of subsynchronous instability of a steam turbine. The optimum schemes are obtained by comparing the rotor responses subjected to maximal radial steam forces in different partial admission schemes. It is found through comparison that the instability of a rotor-bearing system is directly related to the direction of the radial steam force in the partial admission scheme.

An Approximate Analytical Solution for Dynamic Response of a Large Nonlinear Rotor-Bearing System

2016 ◽  
Vol 693 ◽  
pp. 445-452
Author(s):  
Xiao Ying Liu ◽  
Cai Jing Yang ◽  
Li Ping Zhou ◽  
Yu Wang ◽  
Jia Sheng Wang
Keyword(s):  
Analytical Solution ◽  
Dynamic Response ◽  
Dynamic Model ◽  
Nonlinear Dynamic ◽  
Harmonic Balance Method ◽  
Rotating Machinery ◽  
Nonlinear Dynamic Response ◽  
Reduced Order ◽  
Rotor Bearing ◽  
Bearing System

Large nonlinear rotor-bearing system is an important structure in rotating machinery, such as NC machine. Due to the mass imbalance of the system, vibrations induced by centrifugal forces inevitably exist in rotating machinery. So, nonlinear dynamic response of a complex rotor-bearing system was dealt with in this paper. The system considered was modeled using the finite element method and has 124 DOFs (degrees of freedom). A linear reduction method was used and a reduced-order dynamic model of the system with two DOFs had been obtained. Harmonic balance method was applied to the reduced-order dynamic model of the system and an approximate analytical expression of the solution for nonlinear dynamic response of the system at steady state was derived. The analytical solution obtained from the reduced-order dynamic model of the system was compared with the numerical one obtained from the direct integration of the equations of motion of the original system.

Effect of Varying the Number of Rollers on Dynamics of a Cylindrical Roller Bearing

2014 ◽  
Author(s):  
Aditya Sharma ◽  
M. Amarnath ◽  
P. K. Kankar
Keyword(s):  
Nonlinear Dynamic ◽  
Fourier Transforms ◽  
Roller Bearing ◽  
Hertzian Contact ◽  
Design Stage ◽  
Nonlinear Dynamic Model ◽  
Rotor Bearing ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller ◽  
Bearing System

In present paper, nonlinear dynamic model has been developed for cylindrical roller bearings. The Hertzian contact theory is used to derive a two degree of freedom model which considers nonlinearity due to clearance. The nonlinear dynamic behaviour of cylindrical roller bearing has been studied with varying number of rollers supporting load. The modified Newmark-β numerical integration technique has been used to solve the equations of motion. All the results are presented in the form of Fast Fourier Transforms and Poincarè maps. As the number of rollers is increases, system becomes stiffer. The results show that the number of rollers supporting load is one of the important parameters affecting the dynamics of rotor bearing system. Therefore, it must be considered at the design stage to understand the dynamic characteristics and stability of the rotor bearing system.

Analysis of Tourism Ecology Capacity Based on the Nonlinear Dynamic Model

2009 ◽  
Vol 11 (2) ◽  
pp. 163-168
Author(s):  
Long LV ◽  
Zhenfang HUANG ◽  
Jiang WU
Keyword(s):  
Dynamic Model ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Model
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