Rotordynamics

Rotordynamics, also known as rotor dynamics, is a specialized branch of applied mechanics concerned with the behavior and diagnosis of rotating structures. It is commonly used to analyze the behavior of structures ranging from jet engines and steam turbines to auto engines and computer disk storage. At its most basic level, rotor dynamics is concerned with one or more mechanical structures (rotors) supported by bearings and influenced by internal phenomena that rotate around a single axis. The supporting structure is called a stator. As the speed of rotation increases the amplitude of vibration often passes through a maximum that is called a critical speed. This amplitude is commonly excited by unbalance of the rotating structure; everyday examples include engine balance and tire balance. If the amplitude of vibration at these critical speeds is excessive, then catastrophic failure occurs. In addition to this, turbo machinery often develop instabilities which are related to the internal makeup of turbo machinery, and which must be corrected. This is the chief concern of engineers who design large rotors.

Turbo machinery vibration analysis is performed in order to pinpoint and avoid potential failures. It combines shaft vibration analysis techniques, including vibration measurement, phase detection, order tracking, shaft orbits and centreline measurement, with time and frequency analysis to determine the root causes of vibration. Slow roll

compensation techniques are also applied to determine mechanical or electrical run out in most proximity probe monitoring systems.

Rotating machinery specialists study the entire system, employing structural and rotor vibration analysis techniques to measure the shaft, supporting structure and machine casing (bearing housing) to understand how the

rotor and structure behaves under vibratory forces. Wherever possible, recordings of process parameters such as

pressure, temperature, flow, valve positions and control signals are made to form a complete picture of the system.

Application:

  • Turbine & Compressor rotor blades damage.

  • Rotor bends or bow
  • Rotor balancing issue
  • Exhaust pressure issue
  • Turbine bearing wear and tear due to lubrication failure
  • Uneven burning due to air fuel ratio
  • Due to generator load variation and turbine run at over speed
  • Foundation Bolts & grouting problems
  • Misalignment & casing bolts loose or broken