Lateral Rotor Vibration Analysis Model

 Rotor dynamics is the branch of engineering that studies the lateral and torsional vibrations of rotating shaft, with the objective of predictive the rotor vibrations and containing the vibration level under an acceptable limit. Lateral rotor vibration (LRV) is radial-plane orbital motion of the rotor spin axis. Transverse rotor vibration is used synonymously for LRV. Actual LRV orbits are typical only a few hundredths of a millimeter. LRV is an important design consideration in many types of rotating machinery, particularly turboelectrical machines such as steam and combustion gas turbine/generator sets, compressors, pump, gas turbine jet engines, turbochargers and electric motors. Thus LRV affect several major industries. Usually, but not always, the potential for rotor dynamic beam-bending-type deflection significantly contributes to the LRV characteristics. The significance of LRV rotor bending increases with bearing-to-rotor stiffness ratio and with rotor spin speed. Consequently, in some rotating machines with a low operating speed and /or low bearing-to-rotor stiffness ratio, the LRV is essentially of a rigid rotor vibrating in flexible bearing or support. The opposite case (a flexible rotor in essentially rigid bearings) is also possible but rotor dynamically less desirable, because it lacks some vibratory motion at the bearings which often provides that essential ingredients, damping, to keep vibration amplitudes at resonance conditions within tolerable levels. A rotor’s flexibility and mass distributions and it is bearings flexibilities combined with its maximum spin speed essentially determine whether or not residual rotor unbalance can produce forced LRV resonance. That is these factors determine whether the rotor-bearing system has one or more lateral natural frequency modes below the operating speed.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/