A unique type of air lubricated thrust bearing called a Wave Bearing is proposed to assist a rolling element bearing to carry the thrust load and to improve the bearings life when used in a micro gas turbine engine. The Wave Bearing technology will provide improved reliability, safety and life compared to rolling element bearings used alone, as well as to allow simplification of engine design and reduced costs. When compared to its alternatives, the Wave Bearing has distinct advantages. It is much simpler than a Magnetic Bearing and it is less prone to wear than a Foil Bearing. In the proposed Phase I program, computer codes developed by Dr. Dimofte, will be used to adapt the Wave Bearing to the design requirements relevant to the micro gas turbine engines. Test conditions will be thrust loads to 200N, speeds to 100,000 rpm and durations sufficient to prove the demo. The Wave Bearing will be developed and tested in Phase I to assure with reasonable engineering certainty that it is a viable candidate for use in a micro gas turbine engine and the testing will verify that more extensive testing should be conducted in Phase II.
Benefit: Recent technology advancements have enabled the introduction of smaller, more accurate and lower cost missiles and UAV vehicles that have in turn driven down engine size requirements. Next generation small or micro gas turbine engines are ideally suited to these applications. These new small engines are by design run at extremely high speeds and will require advance bearing designs to achieve the durability required for these new engines. The Wave Bearing technology that is being offered in this proposal would facilitate the successful operation of these new engines and resulting vehicles. The Wave Bearing is a self-acting air bearing, which uses the surrounding air as lubricant (without any oil lubrication system). The bearing could be an ideal solution for these engines. The Wave Bearing is one of the simplest air bearings, with competitive performance regarding the load capacity, stiffness and dynamic stability. The alternative type of air bearing is the Foil Bearing. The disadvantage of Foil Bearings as compared to Wave Bearings is that Foil Bearings require a preload. This causes them suffer some wear to the surfaces on startup and shutdown and this wear could limit their lives. Wave Bearings do not have this requirement. The advantages of using Wave Bearing technology is that small and micro gas turbine engines could be made simpler, more efficient and require less maintenance without an oil lubrication system. The Wave Bearing will also provide cost-effective, reliable operation of small aerospace and land-based gas engine systems by improving the in service life of these systems. This technology can in turn extend the market of other gas turbine engine applications, including turboprop, turboshaft and turbo-alternators (for electrical generation or vehicle propulsion). These engines are also multi-fuel capable, including utilizing heavy fuels or new generation biofuels. In addition, the successful application of the Wave Bearing should lead to their use in not only aviation turbine engines, but also in a variety of other high speed rotating machinery applications. Typical examples would include power generating systems and air cycle machines. In this age of focused environmental concerns, the use of Wave Bearings should lead to enhanced environmental efficiencies.
Keywords: Wave Bearings, Wave Bearings, thrust bearings, Fluid Film Bearings, Small Gas Turbine Engines, Air bearings, Bearing Loading, Bearing Rig Testing., Small High Speed Bearings
