Angled injection - turbulent flow hybrid bearings comparison to test results

Hydrostatic/hydrodynamic (hybrid) journal bearings handling process liquids have limited dynamic stability characteristics and their application as support elements to high speed flexible rotating systems is severely restricted. Measurement on water hybrid bearings with angled orifice injection have demonstrated improved rotordynamic performance with virtual elimination of cross-coupled stiffness coefficients and null or negative whirl frequency ratios. A bulk-flow model for prediction of the static performance and force coefficients of hybrid bearings with angled orifice injection is advanced. The analysis reveals that the fluid momentum exchange at the orifice discharge produces a pressure rise in the hydrostatic recess which retards the shear flow induced by journal rotation, and thus, reduces cross-coupling forces. The predictions from the model are compared with experimental measurements for a 45 angled orifice injection, 5 recess water hybrid bearing operating at 10.2, 17.4 and 24.6 krpm and with supply pressures of 4, 5.5 and 7 MPa. The correlations include recess pressures, flow rates, and rotordynamic force coefficients at the journal centered position.

Angled injection - turbulent flow hybrid bearings comparison to test results Conference Paper