WIND ASSISTED PROPULSION: INVESTIGATIONS ON THE USE OF SHIP HOLISTIC MODELS FOR PERFORMANCE ANALYSIS

Abstract

Wind propulsion is one of the most promising technologies to reduce carbon intensity of ships. However, with variable thrust production and induced drift action, sail’s contribution to propulsion is to be evaluated in different ways from traditional propulsors. For sail retrofit projects, where vessels are initially designed to be optimal at single transit speeds with propulsion engine, wind assistance may also induce a degradation of operational efficiency and limit the extend of energy savings. For these reasons, performance analysis should evolve to account for complex energy transfers between propulsion domain and energy systems. A novel Modelica based model is presented in this article, where manoeuvres and energy modelling are used jointly to predict overall efficiency of wind assisted ship concepts. The model is used to evaluate the impact of retrofitting 4 Flettner rotors on the Duisburg test case (DTC) equipped with diesel engines mechanical propulsion system, with oil fired and exhaust gases steam plants and electricity generation from gensets and turbogenerator. Finally, from the analysis of DTC performance in a sweep of wind conditions, potential solutions to increase sailing efficiency are presented, offering new research directions in vessel design adaptation to natural propulsion.