Title page for ETD etd-07052000-14530020


Type of Document Master's Thesis
Author Mendoza, Hector
Author's Email Address hmendoza@vt.edu
URN etd-07052000-14530020
Title Evaluation of the Effectiveness of an Active Magnetic Damper (AMD) in Damping Subsynchronous Vibrations in a Flexible Rotor
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Kasarda, Mary E. F. Committee Chair
Kirk, R. Gordon Committee Member
Wicks, Alfred L. Committee Member
Keywords
  • Active Magnetic Bearing
  • Rotordynamics
  • Active Magnetic Damper
  • Subsynchronous vibrations
  • Active Control
  • Instability
Date of Defense 2000-06-22
Availability unrestricted
Abstract
Subsynchronous vibrations such as those caused by rotor instability represent one of the most harrowing scenarios of rotor vibration. They are related to a great diversity of destabilizing forces and some of them are not well understood yet. Therefore, special attention must be paid to this type of vibration. Active Magnetic Bearings (AMBs) monitor the position of the shaft and change the dynamics of the system accordingly to keep the rotor in a desired position, offering the possibility of being used as dampers for vibration control.

In the present work, a single-disk and a three-disk rotor were built to evaluate the effectiveness of an Active Magnetic Damper (AMD) in damping subsynchronous vibrations. An AMD was used to inject a signal simulating a subsynchronous vibration in the rotor, as another AMD was used to perform active control. Two locations of the AMD were considered for each rotor. For the single-disk rotor, experimental data was taken with the AMD located at three-quarters of the rotor-span and with the AMD located at midspan. For the three-disk rotor, experimental data was taken with the AMD located at a quarter-span and with the AMD at two-thirds of the rotor span.

An undamped critical speed and a forced response analysis were performed on the rotors in order to predict the dynamic characteristics of the rotors with and without the AMD.

It was demonstrated that an AMD is effective in damping subsynchronous vibrations. The addition of an AMD introduces damping and stiffness to the rotor-bearing system resulting in a change in the synchronous response and a consequent increase of the amplitude of vibrations at synchronous frequencies. This effect must be carefully considered when designing a system with an AMD.

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  appendixa.pdf 72.92 Kb 00:00:20 00:00:10 00:00:09 00:00:04 < 00:00:01
  appendixb.pdf 102.20 Kb 00:00:28 00:00:14 00:00:12 00:00:06 < 00:00:01
  appendixc.pdf 103.10 Kb 00:00:28 00:00:14 00:00:12 00:00:06 < 00:00:01
  chapter1.pdf 88.69 Kb 00:00:24 00:00:12 00:00:11 00:00:05 < 00:00:01
  chapter2.pdf 420.37 Kb 00:01:56 00:01:00 00:00:52 00:00:26 00:00:02
  chapter3.pdf 91.11 Kb 00:00:25 00:00:13 00:00:11 00:00:05 < 00:00:01
  chapter3a.pdf 265.16 Kb 00:01:13 00:00:37 00:00:33 00:00:16 00:00:01
  chapter4.pdf 183.26 Kb 00:00:50 00:00:26 00:00:22 00:00:11 < 00:00:01
  chapter5.pdf 173.90 Kb 00:00:48 00:00:24 00:00:21 00:00:10 < 00:00:01
  chapter6.pdf 102.54 Kb 00:00:28 00:00:14 00:00:12 00:00:06 < 00:00:01
  frontmat.pdf 95.08 Kb 00:00:26 00:00:13 00:00:11 00:00:05 < 00:00:01
  references.pdf 50.86 Kb 00:00:14 00:00:07 00:00:06 00:00:03 < 00:00:01
  vita.pdf 46.47 Kb 00:00:12 00:00:06 00:00:05 00:00:02 < 00:00:01

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