Lateral Vibration Analysis of Steam Turbine Rotor- Bearing System

Abstract

Rotating machines are one of the fundamental components of engineering systems and are widely used in the industry today. Dynamic analysis of rotating machines is required in order to analyze behavior of rotating system. In context of the rotor dynamic analysis, the lateral vibration analysis is one of the critical aspect, apart from torsional and axial vibration analysis because often operating frequencies having lateral deflection mode shapes. To avoid resonant conditions at operating speeds, lateral vibration analysis of such rotors is vital in the design and development of the system. The main aim of dissertation work is to provide generalize methodologies to carry out lateral vibration analysis that can be utilize for any types of rotor bearing system. In present work, the bench mark study of three-disk rotor system is carried out by Dunkerley’s method, Rayleigh’s method, Transfer Matrix Method (TMM) using MATLAB and Finite Element Method (FEM) to identify methodologies for evaluation of critical speeds of system which is important aspect of lateral vibration analysis.The study of sample rotor demonstrates detailed approach of preparation of lumped mass model as well as solution of model of rotor using Transfer Matrix Method (TMM).The lateral vibration analysis of actual steam turbine rotor bearing system in the present dissertation is carried out by Finite Element Method (FEM). The lateral vibration analysis includes critical speeds evaluation, operational deflection shapes, static deflection and unbalance response of the rotor in order to completely investigate the dynamic behavior of the rotating system.This report contains, lateral vibration analysis for Actual Steam Turbine Rotor-Bearing System by Transfer Matrix Method (TMM) using SIEMENS’s proprietary software developed in Germany as well as Finite Element Method (FEM) using FEM software. The results obtained from commercially available Computer Aided Engineering tools are compared with SIEMENS’s proprietary software results as well as experimental results. The experimental results shows close confirmation with proposed methodology.