A General-Purpose Test Facility for Evaluating Gas Lubricated Thrust Bearings

The design, construction, operational capabilities, and proof of concept results are presented for a test rig used to evaluate gas-lubricated thrust bearings. The following work is motivated by a desire to utilize the working fluid of high performance turbomachinery such as gas turbines for bearing lubricant. Auxiliary equipment required to cool, pump, and clean oil for a typical thrust bearing is eliminated by taking advantage of the turbomachinery’s working fluid as bearing lubricant. The benefit of removing such auxiliary equipment is obvious when considering cost and weight of turbomachines, yet the working fluid of gas turbines typically has very low viscosity compared to oil which introduces load capacity and stability challenges. It is therefore necessary to build a facility capable of testing gas lubricated thrust bearings to advance the technology. The test rig design allows for 7 to 15 inch (180-380 mm) diameter thrust bearings, static loads up to 30,000 lbs (135 kN), and speeds up to 20 krpm. The test rig design enables bearing load capacity evaluation through static load measurements, rotor torque, and temperature readings on the bearing pads. Additionally, position sensors attached to both the bearing structure and compliant pads allow direct stiffness of the gas film to be calculated. This paper describes the test rig operating principle, details experimental procedures to obtain measurements, and provides test results necessary to prove the test rig concept.