Stability Characteristics of Herringbone Grooved Journal Bearings Incorporating Cavitation Effects

Stabilitycharacteristics of the herringbone grooved journal bearings (HGJBs) are analyzedtaking into account cavitation of the fluid flow. The perturbedvalues of pressure and film thickness from a given equilibriumposition are substituted into the Elrod's universal equation, which considersmass conservation in the complete bearing geometry. In order toanalyze the herringbone groove configuration, the governing equations under steadyand perturbed states are transformed to a rectangular domain usingthe grid transformation techniques. It is assumed that under perturbedconditions, the cavitation extent in the bearing remains unchanged andthe pressure gradients are computed in the full film region.The linearized stiffness and damping coefficients are evaluated in thecomplete bearing geometry from the predicted values of pressure gradients.The threshold speed parameter and whirl frequency ratio are computedusing the linearized stability analysis. Results are generated for variouseccentricity ratios and groove angles. The results of this studyvalidate the use of HGJBs at the very higher operatingspeeds (at concentric journal operation) in rotating machinery.