Examining the Behaviour of Lubricating Oil Film Within Marine Journal Bearing Under Emergency and Critical Operational Conditions

Lubricating oil film within journal bearing is significantly affected by variations in journal shaft speed, especially sudden ones. Abrupt speed alterations may, in certain maneuverability and emergency situations, threaten the main journal bearing and can lead to the rapid deterioration and most possibly the complete failure of journal bearing and major pollution regarding the marine environment. Consequently, the study at hand introduces experimental test trials and the related outcomes regarding the two speed ranges of 50 and 200 rpm, which represent the worst conditions of ship maneuverability. They have comprised a non-stop rapid speed alteration from 50 rpm anticlockwise to 50 rpm clockwise. Additionally, they have been conducted under two modes of alteration, namely: Crash-stop at both an abrupt rapid as well as gradual speed alterations. The research scope has also been extended to trace the impacts of experimenting at a speed of 200 rpm on the lubricating oil film within journal bearing. Based on the conducted tests, the lubricating oil film within journal bearing was concluded to be severely affected under such extreme operating conditions. It is in those cases that lubricating oil film completely deteriorates and suffers the risk of wear, leading finally to the ultimate failure of journal bearing. Moreover, carrying out crash stop procedures at abrupt speed alterations at both 50 and 200 rpm has proven to be seriously detrimental to main bearing and thus to the lubricating oil film. It is in those serious operating conditions that the lubricating oil pressure extensively deteriorates and hence the hazardous contact is inevitable.