Power Loss Mechanism and Efficiency Optimization of Marine Propulsion Shafting: An Integrated Framework Coupling Dynamic Alignment and Whirling Vibration

Abstract Energy losses occurring during power transmission in marine propulsion shafting constitute a critical factor that constrains the overall transmission efficiency, with their underlying loss mechanisms involving intricate multi-physics coupling effects. Targeting the core contributors to power loss-bearing friction and shafting vibration, this study proposes a comprehensive shafting efficiency simulation method that integrates dynamic alignment analysis with lateral vibration modeling. To investigate the power flow characteristics of shafting under dynamic excitation, an integrated dynamic model and a corresponding finite element simulation framework for the shafting-bearing-foundation system were developed. A dedicated shafting efficiency simulation platform was constructed, and the accuracy of the proposed simulation model was verified via bench-scale experiments. Furthermore, the influence patterns of key design parameters and operating conditions on shafting transmission efficiency were systematically examined to delineate their quantitative relationships. The results demonstrate that the integrated simulation method enables accurate evaluation of power losses in shafting across diverse operating conditions, with particularly high precision in high-load, high-speed scenarios. This research offers a robust theoretical tool and a practical solution for assessing energy consumption and optimizing transmission efficiency in marine propulsion shafting systems.