Effect of square-dimple size on dynamic characteristics of textured journal bearings

Abstract

Dynamic characteristics of journal bearings with uniform square dimples on the whole bearing surface are numerically calculated considering the inertia effect and the energy loss based on the oil film discontinuity at the edge of dimples. The comparison of the results with a smooth bearing without dimples shows that all the stiffness and damping coefficients for the textured bearings are smaller than those for the smooth bearing over a wide range of eccentricity ratio. The effects of the number of dimples are investigated under a constant total area of dimples, and the cross-coupled stiffness coefficients decrease significantly at lower eccentricity ratio for the large number of dimples due to the inertia effect and energy loss at the discontinuous dimple edge. The linear stability threshold shaft speeds of a symmetrical rigid rotor increase with the number of dimples, which is attributable to the reduction of the cross-coupled stiffness coefficients.