Vibration Analysis of Gas Turbine Rotors

Table of Contents

• CHAPTER I
  • 1. INTRODUCTION
  • 1.1 Gas Turbine
    • 1.1.1 Theory of Operation
    • 1.1.2 Rotor
  • 1.2 Lateral and Torsional Analysis of Rotor
• CHAPTER II
  • 2. LITERATURE REVIEW
  • 2.1 Lateral Vibration Analysis
  • 2.2 Torsional Vibration Analysis
• CHAPTER III
  • 3. MATHEMATICAL BACK GROUND
  • 3.1 Vibration
    • 3.1.1 Single Degree Freedom Systems
    • 3.1.2 Equation of motion for SDOF
    • 3.1.3 Multi Degree of Freedom (MDOF) System
    • 3.1.4 Vibration Model
    • 3.1.5 Equations of Motion
    • 3.1.6 Viscously Damped of Free Vibration
  • 3.2 Rotor Dynamics
    • 3.2.1 Definition of terms
    • 3.2.2 Damped Unbalance Response Analysis
  • 3.3 Finite Element Method in Rotor Dynamics
    • 3.3.1 Division of Rotor into Discrete Systems
    • 3.3.2 Gyroscopic Effects
    • 3.3.3 Supports
    • 3.3.4 Shear Deformation
    • 3.3.5 Damped Natural Frequency/Stability
  • 3.4 Imbalance Response of Rotor
  • 3.5 Torsional Analysis (Method of Calculation)
    • 3.5.1 Transfer Matrix Analysis
    • 3.5.2 Generation of Campbell Diagrams
    • 3.5.3 Electrical Fault Torque Calculations
• CHAPTER IV
  • 4. RESULTS AND DISCUSSIONS
  • 4.1 Lateral vibration analysis of Frame-GT Train
    • 4.1.1 GT Rotor modeling
    • 4.1.2 Damped Critical Analysis considering minimum stiffness
    • 4.1.3 Unbalance Response Analysis
    • 4.1.4 Logarthmic Decrement and Stability Analysis
  • 4.2 Torsional Vibration Analysis of Rotor Train
    • 4.2.1 Natural Frequency
    • 4.2.2 Torsional Mode Shape
    • 4.2.3 Campbell Diagram
    • 4.2.4 Torque Magnification Factor
    • 4.2.5 Alternating Shaft Stresses

Objectives and Key Themes

This report aims to determine the lateral and torsional dynamic characteristics of a gas turbine rotor system under synchronous excitation conditions. The analysis investigates the combined effects of oil film stiffness and damping on system damping and stability at resonance speeds. The study also explores the system's sensitivity to unbalance.

• Lateral Vibration Analysis of the Rotor System
• Torsional Vibration Analysis of the Rotor System
• Influence of Oil Film Stiffness and Damping on System Stability
• Unbalance Response Analysis and System Sensitivity
• Assessment of Torsional Natural Frequencies and Mode Shapes

Chapter Summaries

Chapter I introduces the gas turbine, its operational theory, and the concept of lateral and torsional analysis. Chapter II provides a literature review on lateral and torsional vibration analysis, covering relevant research and existing techniques. Chapter III delves into the mathematical background of vibration, including single and multi-degree of freedom systems, equations of motion, and finite element methods in rotor dynamics. This chapter also explores the concept of damped natural frequency and stability, imbalance response of the rotor, and torsional analysis methods like transfer matrix analysis and Campbell diagram generation.

Chapter IV presents the results and discussions of the analysis. This chapter examines the lateral vibration analysis of the Frame-GT train, including rotor modeling, damped critical analysis, unbalance response analysis, and stability analysis. It also covers the torsional vibration analysis of the rotor train, including natural frequency, mode shape, Campbell diagram, torque magnification factor, and alternating shaft stresses.

Keywords

This work focuses on gas turbine rotor dynamics, vibration analysis, lateral vibration, torsional vibration, oil film stiffness, damping, unbalance response, natural frequencies, mode shapes, Campbell diagram, transfer matrix analysis, and finite element methods.