Optimization of Stern Bearing Lubrication Performance Under Misaligned Journal Conditions Based on Length-to-Diameter Ratio

Abstract To investigate the impact of the length-to-diameter ratio (LDR) on the lubrication performance of misaligned journal stern bearings, a lubrication model was developed and solved using numerical methods, with experimental validation. Results show that, unlike aligned bearings, the lubrication performance of misaligned bearings initially improves as the LDR increases, reaches an optimal state, and then declines. The LDR corresponding to this optimal state is defined as the optimal length-to-diameter ratio (LDRopt). Further analysis indicates that LDRopt decreases with increasing dimensionless load, misalignment angle, and bearing diameter. A mathematical relationship between LDRopt and these parameters was established using nonlinear fitting. Validation through case studies confirmed its accuracy, demonstrating its high practical value.