Comparison Between Predictions and Experimental Measurements for an Eight Rocket Annular Hydrostatic Thrust Bearing

Abstract : A test rig was designed, produced, and used to test a hydrostatic thrust bearing geometry. In a non-rotational configuration, this test rig uses a hydraulic shaker to load the thrust bearing and rotor. The test hydrostatic thrust bearing has an outer radius of 38.1 mm and an inner radius of 20.32 mm. The bearing has eight pockets spaced evenly at the mid-radius with a supply orifice located in the center of each pocket. This applied force is then reacted by a stationary pedestal that a thrust bearing rests against. The hydrostatic thrust bearing was tested at 3.45, 10.34, and 17.24 bar supply pressure with water at approximately 38oC; each thrust bearing supply pressure was tested with at least ten applied loads spanning the loading range predicted by XLHydroTHRUST. The test results are compared to predictions for flow rate and load versus bearing clearances from XLHydroTHRUST. Predictions correlated reasonably well for flow and load especially for test clearances higher than 0.076 mm where the predictions and measurements agree within 20%. The differences between predictions and measurements may be due to the observed discharge coefficient and thrust bearing face misalignment at low clearance. This discharge coefficient must be given a constant value for XLHydroTHRUST, but significant changes were observed when extracted from the test data. Further investigation may be warranted to account for this discrepancy.