A Review of the Rotordynamic Thermally Induced Synchronous Instability (Morton) Effect

[+] Author and Article Information
Xiaomeng Tong

Member of ASME, Department of Mechanical Engineering, Texas A&M University. College Station. TX. 77840

Alan Palazzolo

ASME Fellow, Department of Mechanical Engineering, Texas A&M University. College Station. TX. 77840

Junho Suh

Member of ASME, Department of Mechanical Engineering, Hankyong National University. South Korea

1Corresponding author.

ASME doi:10.1115/1.4037216 History: Received July 31, 2016; Revised May 27, 2017


The Morton effect (ME) is a thermally induced instability that typically appears in rotating shafts with large overhung masses and fluid film bearings. The time-varying thermal bow due to the asymmetric journal temperature distribution may cause intolerable synchronous vibrations with a hysteresis behavior with respect to rotor speed. Discovered by Morton in the 1970s and theoretically analyzed by Keogh and Morton in the 1990s, the ME is still not fully understood. Traditional rotordynamic analysis generally fails to predict the existence of ME induced instability in the design stage or troubleshooting process. The induced excessive rotor vibrations cannot be effectively suppressed through conventional balancing due to the continuous fluctuation of vibration amplitude and phase angle. A quickly growing number of case studies of ME have sparked academic interest in analyzing the causes and solutions of ME, and engineers have moved from an initial trial and error approach to more research inspired modifications of the rotor and bearings. The current review is intended to provide a comprehensive summary of ME in terms of symptoms, causes, prediction theories and solutions. Published case studies in the past are also analyzed for ME diagnosis based on both the conventional view of critical speed, separation margin and the more recent view of the rotor thermal bow and instability speed band shifting. Although no universal solutions of ME are reported recommendations to help avoid the ME are proposed based on both theoretical predictions and case studies.

Copyright (c) 2017 by ASME
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