Session: Poster Session

Paper Number: 160096

Design and Commissioning of a High-Speed (120,000 Rpm) Hysteresis and Power Loss Test Rig for Air Foil Journal Bearings 

This poster presents the design, commissioning, and initial results of a high-speed hysteresis test rig for beam-type air foil journal bearings (AFJBs) capable of rotational speeds up to 120,000 rpm. The test rig comprises the application of a maximum load of 100 N and the measurement of the deflection of the test bearing as well as bearing temperatures and the viscous frictional torque of high start-up in the range of 130–150 mNm and at constant speed lower than 5 mNm. The rotor is driven by a Pelton air turbine which ensures low disturbance and a wide speed range. The test rig consists of a 27 mm rotor, supported by one aerostatic thrust bearing and two aerostatic journal bearings, with a single test AFJB positioned between the two journal bearings. This configuration offers superior rotordynamic stability compared to overhang designs, effectively decouples disturbing influences of the rotor bearing system for accurate quasi-static measurements. Additionally, the aerostatic bearings offer the benefit of easy, unlimited assembly and disassembly of the rotor without risk of damage. Comprehensive repeat measurements and uncertainty quantifications are carried out to ensure the precision and reliability of the measurements. Viscous frictional torque measurements provide valuable insights into power losses, lift-off speed and break-away torque during the running-in phase of the bearing. Rotordynamic stability was proven in tests without the test bearing, with rotor amplitudes remaining below 2 µm across the entire speed range. The first successful measurement series showcase reliable and accurate measurement conditions for power loss, rotor temperatures and hysteresis properties.

Presenting Author: David Braxmaier Robert Bosch GmbH

Presenting Author Biography: Education:
Bachelor’s and Master’s in Mechanical Engineering, University of Stuttgart (2014–2021)
Master thesis at Robert Bosch GmbH: Experimental and numerical investigations of inertial
effects on aerodynamic thrust bearings

Professional Experience:
Development Engineer for Gas Bearing Design and Testing Engineer in the High-Speed Products Department, Bearings and Rotor Dynamics Group, ebm-papst Mulfingen (2021–2022)

Current Role:
PhD Candidate at Robert Bosch GmbH (2022–present): Experimental Validation of Air Foil Journal Bearing Models.

Authors:

David Braxmaier Robert Bosch GmbH
Felix Foerster Robert Bosch GmbH