CFD-BASED OPERATION OPTIMIZATION OF HYBRID SHIPS

Hybrid propulsion technology is interesting for shipping, both due to possible reduction in fuel cost and strict emission regulations. The efficiency of a hybrid propulsion system will however depend on the power system configuration and the choice of power and energy management strategies. In this study, a simulation model is developed based on CFD, to investigate power management strategies of hybrid propulsion during transit operation. Two engineering operation approaches using fixed RPM mode and fixed power mode are simulated, in order to investigate power management strategy of the hybrid propulsion system. The transition operation of offshore supply vessel Viking Lady is used as an investigated object in the present study. The numerical simulations are performed in both regular sea and irregular sea. CFD results show that the models with the fixed RPM mode and the fixed Power mode give similar results in the power consumption, provided that the ship resistance in waves is predicted accurately as well as the output power and propeller revolution rate are properly designed. The model with the fixed RPM was expected to be able to reduce the power consumption by minimizing ship speed fluctuations when running in heavy sea conditions. The present numerical results show that the fixed RPM mode tried to reduce ship speed change by changing output power. However, it is not able to reduce the change of ship speed efficiently when the first-order wave forces are significantly large, and the power consumption is consequently not reduced.