The effects of dimensional manufacturing tolerances on stability of a symmetric hydrodynamic journal bearing rotor system – an experimental investigation

The importance of gross dimensions on the design and operation of hydrodynamic journal bearing system are widely understood, however, the effects of manufacturing tolerances have only been macroscopically analysed. Building on previous theoretical analyses, an experimental investigation on the effect of dimensional manufacturing tolerances is presented. Importantly, the study looks at individual effects and combined effects. The experimental data suggested that the error created by manufacturing tolerances in estimating the onset of oil film instability can be as much as ±20 per cent, depending on the steady state operating position. This finding shows that in order to minimize the effect of manufacturing tolerances on system stability, the hydrodynamic journal bearing system should be designed to operate at a modified Sommerfeld number greater than 0.1, where the effects of manufacturing tolerances on system stability are negligible.