Transition From Laminar to Turbulent Flow Regime in Thin Lubricating Film Between a Stationary and a Rotating Disk

Increasing in rotational speed in turbo machineries such as turbochargers or turbo-compressors, several types of fluid film bearings are operated in turbulent flow regime. The transition from laminar to turbulent flow regime causes a remarkable change in bearing characteristics. To predict the transition condition, therefore, is of importance for the design of high speed bearings. The purpose of this paper is to investigate the critical Reynolds number in thin lubricating film of thrust bearings and the fluid film characteristics in transient to turbulent flow regime. An experimental study for a sector-shaped parallel plane thrust bearing shows a decrease in bearing temperature due to the transition, and results in that the critical Reynolds number is 400∼600. The critical Reynolds number obtained is smaller than the result of linear stability analysis, in which an infinitesimal perturbation has been assumed. The reason of this difference is considered to be an effect of finite disturbance and local temperature rise in the bearing. THL analysis in laminar to turbulent flow regime results in reasonable agreement with the experimental results with respect to bearing temperature.