Wind Assisted Ship Propulsion: A Code for Flettner Rotor Feasibility Studies

The harvesting of wind energy and its transformation into a thrust force for the ship propulsion is gaining popularity due to the expected benefit in emission reduction. To exploit the benefit, a proper integration between the conventional diesel engine-screw propeller propulsion plant and the wind assisted plant is mandatory. This paper aims to study the integration of the Flettner rotor technology with a conventional ship propulsion plant with controllable pitch propellers. A mathematical model describing the behaviour of the rotor in terms of propulsive thrust and power is proposed. The rotor model has been integrated into an existing diesel propulsion model to evaluate the ship net fuel consumption. The integrated propulsion model is written in parametric form with respect to the following design parameters: ship dimensions and resistance-speed curve, propeller diameter, rotor geometry and true wind conditions. The described methodology allows to evaluate the engine-propeller working points and finally the total ship propulsive power considering the influence of the rotor, for a given wind condition. The methodology provides a way to compare integrated propulsive solutions in terms of required power.