Session: 27-03 Bearing Effects and Stability in Rotordynamics

Paper Number: 123497

123497 - Experimental and Analytical Stability Investigation of High Speed Rotors Supported on Novel Internally Skewed Journal Bearings in a 60000 RPM Test Rig 

This paper presents the experimental and analytical stability investigation of high speed rotors supported on novel skewed journal bearings in a 60000 RPM test rig.  The stability of turbocharger rotors has been widely investigated.  Some expensive solutions for the stability of turbocharger rotors have been proposed, however this paper provides a simple bearing design with a skewed journal bearing that can be easily and simply applied to turbocharger rotors. 

In this paper the analytical model of the skewed journal bearings is first developed.  Then the numerical analysis and the experimental stability results are provided for a 60000 rpm turbocharger test rig with a simple journal bearing, a floating ring bearing, and a skewed journal bearing.  The skewed journal bearing showed superior stability characteristics both numerically and experimentally.  In fact the test rig was stable with the skewed journal bearing up to the maximu speed of the test rig of 60000 rpm. 

The shaft centerline position in the bearings is also presented, as well as the power loss in the skewed journal bearings, thus providing a complete analysis of these skewed journal bearings.  Design considerations are also discussed at the end of the paper.

Numerical analysis of a 240000 rpm test rig also showed the superior stability characteristics of the skewed journal bearing.  Currently, testing on a 240000 rpm test rig are being conducted.

Presenting Author: Aly El-Shafei Cairo University

Presenting Author Biography: Dr. Aly El-Shafei is a Certified Vibration Analyst, Category IV. He holds a Ph.D. from the Massachusetts Institute of Technology (MIT) and is a world renowned expert on vibration analysis, rotordynamics and machinery diagnostics. In addition to serving as Managing Director at RITEC, Dr. El-Shafei is also a Professor of Vibration Engineering at Cairo University, Egypt and is the Vice President of the Vibration Institute, USA. Prof. El-Shafei chairs the ISO working group ISO/TC108/SC2/WG10 responsible for developing international standards on machinery vibration diagnostics ISO 13373, and serves on the IFToMM Scientific Committee on Rotordynamics, the Vibration Institute Training Committee and the IMechE Scientific Committee on Vibrations in Rotating Machinery. Dr. El-Shafei is known as a seasoned diagnostics engineer and has solved many chronic problems worldwide. He is also known worldwide for his work on Squeeze Film Dampers, and for developing new technology for the control of rotating machinery vibration. Prof. El-Shafei is the recipient of the distinguished Grand African Innovation Award in 2017. Dr. El-Shafei has received 5 US patents and has published more than 80 papers on rotordynamics and machinery diagnostics.

Authors:

Aly El-Shafei Cairo University
Mohamed S. Ibrahim Cairo University
Antoine S. Dimitri Cairo University