High-Reliability Gas-Bearings for Military Air Cycle Machines

Air cycle machines (ACM) are critical components that provide refrigeration in military and commercial aircraft. These systems extract bleed air from the aircraft’s engines or an auxiliary power unit, and refrigerate it for cooling the environment or electronics. Currently, ACMs utilize hydrodynamic foil-bearings to support the expansion turbine at high operating speeds. These bearings have exhibit premature degradation or failure due to contamination and bearing overload. Creare’s proposed approach is an advanced oil-free bearing system that meets both high-load capacity and high-reliability requirements for demanding ACM systems by: (1) eliminating start-up and shut-down preload forces, (2) utilizing hard-coatings on the bearing surfaces, and (3) implementing an active contamination mitigation system. The bearing concept has heritage from our high reliability turbomachines for long-duration space missions. During the Phase I project, we will demonstrate feasibility of our innovation for ACM applications through load and contamination tolerance testing on the journal bearings. Once feasibility is established, we will begin extending the system to ACM thrust bearings during the Option Phase. During Phase II, we will implement our bearing technology into an F 18 ACM platform and demonstrate the load capacity and reliability of our system in an operational ACM.