Stability Characteristics of Herringbone Grooved Journal Bearings Incorporating Cavitation Effects

Abstract

Stability characteristics of the herringbone grooved journal bearings (HGJBs) are analyzed taking into account cavitation of the fluid flow. The perturbed values of pressure and film thickness from a given equilibrium position are substituted into the Elrod’s universal equation, which considers mass conservation in the complete bearing geometry. In order to analyze the herringbone groove configuration, the governing equations under steady and perturbed states are transformed to a rectangular domain using the grid transformation techniques. It is assumed that under perturbed conditions, the cavitation extent in the bearing remains unchanged and the pressure gradients are computed in the full film region. The linearized stiffness and damping coefficients are evaluated in the complete bearing geometry from the predicted values of pressure gradients. The threshold speed parameter and whirl frequency ratio are computed using the linearized stability analysis. Results are generated for various eccentricity ratios and groove angles. The results of this study validate the use of HGJBs at the very higher operating speeds (at concentric journal operation) in rotating machinery.