Session: 23-05 Special Bearings

Paper Number: 153928

A Novel Measurement Method for Investigating the Lift-Off Behavior of Gas Polymer Bearings 

Gas polymer bearings (GPBs) are innovative machine elements for supporting high-speed rotors in oil-free turbomachinery applications. By using air as the lubricating medium, GPBs operate without contamination from lubricating oil. This property makes GPBs eminently suitable for use as bearings in air compressors of fuel cell systems. In cyclical operating scenarios with frequent start-stop cycles the utilization of gas polymer bearings can result in increased wear during the run-up and coast-down phases and thus lead to a shorter service life of the GPBs. The measurement of frictional torque in order to determine the rotor lift-off and touchdown speeds is of great importance for investigating the lift-off behavior and thus the bearing functionality. Therefore this paper presents a novel experimental measurement method for measuring the frictional torque of gas polymer bearings. Existing test rigs feature undesirable friction in their design, which introduces measurement deviations, or stand out due to a complex design to compensate for errors such as parasitic loads, making the measurement results difficult to interpret. The new test rig concept addresses these problems and leads to more precise measurement results with a reduced level of complexity. The method used to apply the static bearing load and the direct mounting of the investigated GPB on the load cells represent the unique features of this study. This novel measurement method has the potential of being established as a new standard for future investigations of lift-off behavior of gas polymer and gas foil bearings. Firstly, the test rig setup of the novel measurement method is illustrated and described. The measurement results of frictional torques as well as lift-off and touch-down speeds of GPBs with different configurations acquired with the new test rig are presented. Finally, the results presented are compared to the measurement results of the commonly used measurement method, in order to demonstrate the improvement in results.

Presenting Author: Aryan Ghomashi Technische Universität Berlin

Presenting Author Biography: Aryan Ghomashi received a master's degree in mechanical engineering from Technische Universität Berlin and has been working as a research assistant in the field of rotordynamics since 2023.

Authors:

Aryan Ghomashi Technische Universität Berlin
Robert Liebich Technische Universität Berlin