Measurements versus Predictions for a Hybrid (Hydrostatic Plus Hydrodynamic) Thrust Bearing for a Range of Orifice Diameters
NORTHROP GRUMMAN INC REDONDO BEACH CA
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A fixed geometry hybrid thrust bearing is investigated with three different supply orifice diameters. The test rig uses a face-to-face thrust bearing design, with the test bearing acting as the rotor loading mechanism. A hydraulic shaker applies the static axial load, which is reacted by a second thrust bearing. The rotor is supported radially by two water-lubricated fluid film journal bearings and is attached to a 30,600 rpm motor via a high speed coupling with very low axial stiffness. Thrust bearings with three different orifice diameters 1.63, 1.80, and 1.93 mm are tested for a range of supply pressures, fluid film thicknesses, and rotational speeds. The water-lubricated test bearings have eight pockets, with feed orifices located centrally in each pocket. Comparisons are presented for the experimental results to predictions found using bulk flow model HYDROTHRUST. Analysis of the data reveals generally good agreements between predictions and measurements. Thrust-bearing inlet supply and inner radius flow rates all decreased with decreasing orifice diameters and bearing axial clearances. In most cases, the bearings with larger orifice diameters exhibit higher recess pressure ratios, operating clearances, and flow rates. The largest orifice bearing does not display higher recess pressure ratios or operating clearances at high speeds for some supply pressures, but it does continue to require additional lubricant flow rate compared to the smaller orifice bearings.
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