Session: 27-03 Bearing Effects and Stability in Rotordynamics

Paper Number: 128308

128308 - A Study on Average Eigenvalue Sensitivity for the Improvement of Rotordynamic Stability of Integrally Geared Centrifugal Compressors 

This paper presents a study on the average eigenvalue sensitivity to design variables of an integrally geared centrifugal compressor pinion-bearing system and its application to the improvement of the rotordynamic stability. The average eigenvalue sensitivity is the approximation of the eigenvalue sensitivity, i.e., the central difference of eigenvalue is substituted for the partial derivative of eigenvalue with respect to a design variable. Hence, the average sensitivity coefficients can be calculated using a rotordynamic analysis program integrated with a bearing analysis program. The results are presented in a new frequency versus logarithmic decrement diagram, which is designed for multiple analysis cases.

The average eigenvalue sensitivity to the mass properties of an impeller can not only predict how much an eigenvalue of interest varies with the mass properties, but also indicate where the impeller should be modified. The average eigenvalue sensitivity to a bearing design variable strongly depends upon pad length, bearing load and pivot offset. The sensitivity study tells what design variables should be changed for satisfactory rotordynamic stability and bearing performance. The effects of main shaft dimensions on the average eigenvalue sensitivity are examined to select and tune certain dimensions for the rotordynamic stability. This numerical method has been implemented to improve the rotordynamic stability of two compressor pinions.

Presenting Author: Zhusan Luo Linde, Inc.

Presenting Author Biography: Zhusan Luo is a Sr. Lead Rotordynamics Engineer of Turbomachinery Department, Linde Inc. in Tonawanda, New York, USA. Dr. Luo is responsible for the rotordynamic design, analysis and testing of Linde turbomachinery. Prior to joining Linde, he worked with Siemens Industrial Turbomachinery Ltd., Lincoln, UK as a Lead Rotordynamics Engineer. He received his B.E. and M.A.Sc. in Mechanical Engineering from Nanjing University of Aeronautics and Astronautics, Nanjing, China and Ph.D. in Applied Mechanics from the University of British Columbia, Vancouver, Canada. Dr. Luo is a member of the ASME, the Vibration Institute, and the IMechE and a Chartered Professional Engineer registered with UK Engineering Council.

Authors:

Zhusan Luo Linde, Inc.
Carl Schwarz Linde, Inc.