Reducing Friction of Heavy Duty Hydrodynamic Pod-Drive Bearing by Means of Lubrication Control and AE Condition Monitoring

摘要

Pod-drives have gained a position as a major propulsion system in e.g.luxury cruise liners and ice going vessels. Typical operating data for pod-drives are driving power up to 20 MW, maximum shaft speeds of 140 rpm and shaft diameters exceeding 700 mm. With continuously growing operation expenses, e.g. fuel, the need to save energy has become more and more essential. One method to increase energy efficiency is by reducing friction. Friction of hydrodynamic journal bearings is dominated by external forces, topography and viscosity of the lubricant. While external forces and topography are predefined by operating conditions and manufacturing processes, fluid film friction can be reduced by either decreasing the viscosity or the lubricant flow rate. Reducing the lubrication amount or the viscosity however may lead to overheating or collapse of the load carrying fluid film, both resulting in a journal bearing failure. This paper presents an approach to safely reduce the lubrication flow within the drive-end bearing of a pod-drive with 770 mm shaft diameter.