Session: 27-03: Bearings Effects in Rotordynamics

Paper Number: 153065

Transient Response Analysis of High-Speed Rotor With Different Bearing Interface and Their Trade-Off 

An aircraft and/or helicopter typically includes an auxiliary power unit (APU). The APU is used to supply electrical power to systems and components while the aircraft is parked on the ground, in flight, and during aircraft taxiing or landing. In some applications, the APU also provides the bleed air to the main engine. The APU is generally comprised of a compressor, which is operatively connected to a generator to drive it. The generator produces the electrical power required to drive the systems and components.  In the case where a critical speed of the high-speed rotor is present within the operating range, it is not desirable to operate at or near this mode due to adverse impacts to the life of bearing, rotor, and APU component vibratory fatigue.  There are number of solutions available to change the critical speed.   In this paper, the Transient response analysis of high-speed generator for the APU were performed for the different interface between bearing and housing, which are considered which are as follows:

a)      Air gap between ball bearing and housing at driving end. 

b)     Air gap between ball bearing and housing at non driving end,

c)      O ring between ball bearing and housing at both ends, 

d)     Tolerance Ring between ball bearing and housing at both ends, 

e)     Wire Mesh between ball bearing and housing at both ends,  and

f)       Squeeze film damper at both end of bearings 

The goal of this paper is to provide the Campbell diagram and nonlinear transient response analysis of the above-mentioned interfaces.   The final selection of the above interface is based on the margin from the operating speed range and transient response analysis.  In addition, sensitivity of stiffness housing was performed to achieve the criteria, that is at least  +/- 20% away from the operating speed range. 

Presenting Author: Parag Mathuria Pratt & Whitney

Presenting Author Biography: Parag Mathuria is Rotodynamics Practitioner at Pratt and Whitney since 2016. He has accumulated extensive experience in 26+ years in the field of Mechanical engineering specialized in vibration. He earned PHD in Mechanical Engineering from IIT Bombay. He has published 25+ Journal and conference papers in sound and vibration and two patents. His most recent endeavors have been to perform the rotodynamic analysis in APU, Aero-engine and Rigs using experimental and analytical tools.

Authors:

Parag Mathuria Pratt & Whitney
Gregory Savela Pratt and Whitney