Investigation of Air Bearings for Small High-Performance Aircraft Gas Turbines

Abstract

High temperatures and rotative speeds of future U. S. Army aircraft propulsion systems will impose increasingly severe operating requirements on oil-lubricated engine bearings and associated seals. Accordingly, air-lubricated bearings are being investigated as a possible approach to alleviating the lubrication problems. This paper presents the results of design and performance studies, as well as bearing component tests, relative to applying air bearings to a two-shaft, 3.5-lb/sec turboshaft engine. The test results verify that air bearings can carry the maximum loads imposed by flight and landing conditions, and can survive the sliding contacts associated with 15,000 engine start/stop cycles. Incentives for pursuing the air-bearing approach are identified, as are also the development and problem areas.