An engineered thermal management is fundamental to the application of gas foil bearings (GFB) as turboshaft supports in rotorcraft propulsion systems. The paper presents a model for the thermal energy transport in a rotor-GFB system operating at high temperature with typical inner and/or outer cooling flows. Predicted film temperatures agree with published test data, demonstrating the effectiveness of an outer cooling stream to remove heat and to control the operating temperature. The inner flow stream is not as efficient. The analysis shows paths of thermal energy by conduction and convection to assist in the design and troubleshooting of rotor-GFB systems operating hot. Bearing temperatures and shaft motions measurements are obtained in a test rotor, electrically heated to 132 deg C. In speed-up tests to 26 krpm, the rotor motion amplitude drops suddenly just above the critical speed, thus evidencing the typical hardening of compliant bearings. At the hottest test condition, since air is more viscous, the rotor peak motion amplitude decreases, not showing a jump. The coastdown tests show the critical speed increases slightly as the temperature rises.
Thermohydrodynamic model predictions and performance measurements of bump-type foil bearing for oil-free turboshaft engines in rotorcraft propulsion systems
Thermohydrodynamisches Vorhersagemodell und Leistungsmessungen von Stoßfolienlagern für ölfreie Propellerturbinentriebwerke in Vortriebssystemen von Drehflügelflugzeugen
AHS International, Annual Forum, 65 ; 1720-1731
2009
12 Seiten, 18 Bilder, 3 Tabellen, 24 Quellen
Aufsatz (Konferenz)
Englisch
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