RESEARCH PAPERS: Gas Turbines: Vehicular

F117-PW-100 Hybrid Ball Bearing Ceramic Technology Insertion

[+] Author and Article Information
J. R. Miner

Pratt & Whitney, United Technologies, West Palm Beach, FL 33410

J. Dell

Wright Laboratory, United States Air Force, Dayton, OH 45433

A. T. Galbato, M. A. Ragen

MRC Bearings, A Unit of SKF USA, Jamestown, NY 14701

J. Eng. Gas Turbines Power 118(2), 434-442 (Apr 01, 1996) (9 pages) doi:10.1115/1.2816608 History: Received March 18, 1995; Online November 19, 2007


Results of an Advanced Research Projects Agency (ARPA) sponsored project to demonstrate the operational benefits of incorporating advanced structural ceramic ball elements into the F117-PW-100 aircraft gas turbine engine high rotor thrust bearings is described. This program consists of design, fabrication, and experimental evaluation of candidate hybrid ball bearing designs in Pratt & Whitney and MRC Bearings test facilities. The bearing design criteria and development test conditions utilized for the project are compatible with the requirements of the F117-PW-100 engine system application. Two hybrid bearing designs were produced by analytically varying internal geometry features such as M-50 race curvatures and contact angles to optimize for the modulus of elasticity of the ceramic balls. CERBEC grade NBD 200 silicon nitride ceramic balls (1 1/8 in. size) demonstrated integrity and a quadruple rolling contact fatigue life improvement versus state-of-the-art M-50 steel balls in single ball test rigs. Thermal performance data obtained in full-scale bearing rig performance testing with 178 mm size hybrid and all-steel baseline bearings shows comparable characteristics. The hybrid bearing displayed a distinct survivability benefit in bearing liquid lubricant starvation testing. Two dozen hybrid bearings will be fabricated for full-scale bearing rig endurance tests to be conducted in 1995–1996 as a prerequisite to validation in operating F117-PW-100 engines in 1996–1997.

Copyright © 1996 by The American Society of Mechanical Engineers
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