Description:
OBJECTIVE: Develop turbine and/or rotary engine rotor bearing technologies primarily targeting significant improvements in durability and cost reduction with a secondary objective of weight reduction.
DESCRIPTION: Propulsion systems for unmanned aerial vehicle (UAV) applications have been notoriously unreliable and expensive to maintain. Significant cost savings and aircraft reliability improvements could be achieved simply through improvement of the durability of the engine mechanical systems. To this end, the United States Air Force is looking for innovative rotor bearing technologies for small turbine and rotary engines (<200 lb. thrust, <200 hp.). Technologies of interest include wear resistant coatings and solid lubricant coatings to improve durability of rolling element bearings or development of low-cost air bearing systems for infinite life. As improved range and loiter are of interest for UAV applications, reduced weight systems are highly prized. It is estimated that oil-free systems can provide a weight reduction of up to 30 percent the total engine weight through removal of accessories and plumbing associated with the oil lubrication system. Air bearings are a straight forward method of providing an oil-free system, but other options for rolling element bearings exist, such as fuel lubricated bearings. It is recommended that the small business team with an engine manufacturer to increase commercialization and transition potential. Efforts should be planned such that technical, schedule, and cost risk is minimized to the greatest extent possible.
PHASE I: Demonstrate feasibility and benefits of the bearing concept through analysis and/or benchtop testing.
PHASE II: Manufacture a prototype of the bearing concept and perform an engine condition representative test to demonstrate TRL 5.
PHASE III: Produce and supply bearing concept to an original equipment manufacturer (OEM) of an emerging turbine or rotary engine system or a retrofit of an existing engine system. This technology may be applicable to cruise missile, high-endurance UAV, attributable UAV, and distributed propulsion applications. PRIVATE SECTOR POTENTIAL/DUAL-USE APPLICATIONS: This technology is likely to have application in commercial applications including turbochargers, air compressors, gas turbines, auxiliary power units, and gas turbine engines for general aviation aircraft.
REFERENCES:
1: Kim, D., Nicholson, B., Rosado, L., and Givan, G., "Rotordynamics Performance of Hybrid Foil Bearing Under Forced Vibration Input," Paper No. GT2017-65233, Proceedings of the ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exhibition, Ch
2: Heshmat, H., Walton II, J., and Tomaszewski, M., "Demonstration of a Turbojet Engine Using an Air Foil Bearing," Paper No. GT-2005-68404, Proceedings of the ASME Turbo Expo 2005, Power for Land, Sea, and Air, Reno-Tahoe, NV., June 6-9, 2005.
3: Kim, D., Varrey, M. K., "Feasibility Study of Oil-Free T700 Rotorcraft Engine: Hybrid Foil Bearing and Nonlinear Rotordynamics," Annual Forum Proceedings - AHS International, v. 4, p 2341-2349, 68th American Helicopter Society International Annual For
4: Heshmat, H., Zhaohui, R., Hunsberger, A., Walton, J., Jahanmir, S., "The Emergence of Compliant Foil Bearing and Seal Technologies in Support of 21st Century Compressors and Turbine Engines," ASME International Mechanical Engineering Congress and Expo
KEYWORDS: Bearings, Lubricant, Oil-free, Anti-wear, Coatings, Small Engine
CONTACT(S):
Brian Nicholson
(937) 255-7567
brian.nicholson.1@us.af.mil
