Theoretical and experimental comparisons for rotordynamic coefficients of a high-speed, high-pressure, orifice-compensated hybrid bearing
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Comparisons are presented between measurements and predictions for a 76.2 mm diameter, high-speed (24,600 rpm), high-pressure (7.0 MPa), hybrid bearings using warm (54°C) water as a test fluid. 'Hybrid' refers to combined hydrostatic and hydrodynamic action. Test results are presented for an orifice-fed, square-recess configuration with five recesses. Data are provided for rotordynamic coefficients including direct and cross-coupled stiffness, direct damping, direct added-mass coefficients, and the whirl-frequency ratio. Experimental results are compared to predictions from an analysis by San Andres (1990a), which accounts for both temporal and convective acceleration terms in the fluid film. San Andres' development uses an orifice discharge coefficient to model the pressure drop from supply pressure to recess pressure. With experimentally determined discharge-coefficient values as input, good agreement is obtained between theory and experiment. However, predictions are sensitive to changes in the orifice discharge coefficients.
author list (cited authors)
Franchek, N. M., Childs, D. W., & San Andres, L.