Influence of transient operating conditions on propeller shaft bearings

Abstract

Recent years have seen some severe sterntube bearing damages, often following a sharp course change. This paper presents the development of a simulation model for oil lubricated journal bearings along with extensive measurements of the conditions in the aft sterntube bearing of a twin propeller Ro-Ro vessel. Results of these investigations demonstrate that hydrodynamic forces at the propeller during manoeuvring considerably influence the performance of the aft sterntube bearing. Depending on the character of the manoeuvre, the journal gets tilted downwards to the aft end of the bearing or in a more horizontal direction towards the oil grooves, respectively. The measurements confirm the suitability of the calculation program to simulate the bearing conditions. Therefore, it is possible to evaluate the effect of design modifications on bearing performance and particularly on oil film thickness.