Synchronous Thermal Instability Evaluation of Medium Speed Turbocharger Rotor-Bearing Systems
Rotors in fluid-film bearing supported turbomachinery are known to develop elliptical orbits as a result of rotor-bearing interactions, mass unbalance within the rotor, gravitational bending of the shaft and external excitation. In synchronous whirl, where the speed at which the shaft travels about...
Main Author: | |
---|---|
Other Authors: | |
Format: | Others |
Published: |
Virginia Tech
2014
|
Subjects: | |
Online Access: | http://hdl.handle.net/10919/32886 http://scholar.lib.vt.edu/theses/available/etd-05162012-114120/ |
id |
ndltd-VTETD-oai-vtechworks.lib.vt.edu-10919-32886 |
---|---|
record_format |
oai_dc |
spelling |
ndltd-VTETD-oai-vtechworks.lib.vt.edu-10919-328862020-09-26T05:35:57Z Synchronous Thermal Instability Evaluation of Medium Speed Turbocharger Rotor-Bearing Systems Carroll, Brian R. Mechanical Engineering Kirk, R. Gordon Kasarda, Mary E. F. Kornhauser, Alan A. Turbocharger Rotordynamics Morton Effect Rotors in fluid-film bearing supported turbomachinery are known to develop elliptical orbits as a result of rotor-bearing interactions, mass unbalance within the rotor, gravitational bending of the shaft and external excitation. In synchronous whirl, where the speed at which the shaft travels about the orbit is equal to the rotational speed of the rotor, temperature gradients may develop across the journal as a result of viscous shear in the bearingâ s lubricant film. This thermal gradient leads to bending of the shaft in a phenomenon known as The Morton Effect. Such thermally induced bending causes further growth of the elliptical orbit resulting in further bending leading to excessive vibration levels and premature bearing failure. This analysis examines the development of the Morton Effect in medium-speed turbochargers typical to shipboard propulsion engines and the effect that bearing clearance has on thermal stability. Floating ring and tilting pad journal bearings are considered with a single stage, overhung centrifugal compressor and an overhung axial turbine. Results indicate a correlation between bearing clearance and thermal stability in the rotor-bearing system. A model for the aerodynamic force generated as a result of interaction between air exiting a centrifugal compressor and the compressorâ s annulus in a turbocharger is then developed and applied to the rotor-bearing systems. Results suggest little correlation between this aerodynamic force and the development of the Morton Effect. Master of Science 2014-03-14T20:37:17Z 2014-03-14T20:37:17Z 2012-05-09 2012-05-16 2012-06-05 2012-06-05 Thesis etd-05162012-114120 http://hdl.handle.net/10919/32886 http://scholar.lib.vt.edu/theses/available/etd-05162012-114120/ Carroll_BR_T_2012.pdf Carroll_BR_T_2012_Copyright.pdf In Copyright http://rightsstatements.org/vocab/InC/1.0/ application/pdf application/pdf Virginia Tech |
collection |
NDLTD |
format |
Others
|
sources |
NDLTD |
topic |
Turbocharger Rotordynamics Morton Effect |
spellingShingle |
Turbocharger Rotordynamics Morton Effect Carroll, Brian R. Synchronous Thermal Instability Evaluation of Medium Speed Turbocharger Rotor-Bearing Systems |
description |
Rotors in fluid-film bearing supported turbomachinery are known to develop elliptical orbits as a result of rotor-bearing interactions, mass unbalance within the rotor, gravitational bending of the shaft and external excitation. In synchronous whirl, where the speed at which the shaft travels about the orbit is equal to the rotational speed of the rotor, temperature gradients may develop across the journal as a result of viscous shear in the bearingâ s lubricant film. This thermal gradient leads to bending of the shaft in a phenomenon known as The Morton Effect. Such thermally induced bending causes further growth of the elliptical orbit resulting in further bending leading to excessive vibration levels and premature bearing failure. This analysis examines the development of the Morton Effect in medium-speed turbochargers typical to shipboard propulsion engines and the effect that bearing clearance has on thermal stability. Floating ring and tilting pad journal bearings are considered with a single stage, overhung centrifugal compressor and an overhung axial turbine. Results indicate a correlation between bearing clearance and thermal stability in the rotor-bearing system.
A model for the aerodynamic force generated as a result of interaction between air exiting a centrifugal compressor and the compressorâ s annulus in a turbocharger is then developed and applied to the rotor-bearing systems. Results suggest little correlation between this aerodynamic force and the development of the Morton Effect. === Master of Science |
author2 |
Mechanical Engineering |
author_facet |
Mechanical Engineering Carroll, Brian R. |
author |
Carroll, Brian R. |
author_sort |
Carroll, Brian R. |
title |
Synchronous Thermal Instability Evaluation of Medium Speed Turbocharger Rotor-Bearing Systems |
title_short |
Synchronous Thermal Instability Evaluation of Medium Speed Turbocharger Rotor-Bearing Systems |
title_full |
Synchronous Thermal Instability Evaluation of Medium Speed Turbocharger Rotor-Bearing Systems |
title_fullStr |
Synchronous Thermal Instability Evaluation of Medium Speed Turbocharger Rotor-Bearing Systems |
title_full_unstemmed |
Synchronous Thermal Instability Evaluation of Medium Speed Turbocharger Rotor-Bearing Systems |
title_sort |
synchronous thermal instability evaluation of medium speed turbocharger rotor-bearing systems |
publisher |
Virginia Tech |
publishDate |
2014 |
url |
http://hdl.handle.net/10919/32886 http://scholar.lib.vt.edu/theses/available/etd-05162012-114120/ |
work_keys_str_mv |
AT carrollbrianr synchronousthermalinstabilityevaluationofmediumspeedturbochargerrotorbearingsystems |
_version_ |
1719341897147744256 |