Experimental Investigation of Rotor Sail Power Requirements

Abstract

In accordance with global climate policies, the International Maritime Organization (IMO) has introduced strict regulations to reduce greenhouse gas (GHG) emissions in the maritime shipping industry. This has created significant impetus to pursue new technologies to meet these regulations, all the while continuing to satisfy the increasing demand of international shipping. Rotor sails are a simple and fuel-efficient supplement to conventional propulsion methods that can be retrofitted onto existing ships. These devices, consisting of a vertical rotating cylinder, generate thrust from the wind through the Magnus effect and can provide fuel savings of up to 25%. However, there is currently no reliable method to accurately predict rotor sail power requirements, leaving engineers unable to incorporate these devices into designs without introducing significant risk and/or uncertainty. The development of a reliable and standardized method to determine power requirements for rotor sails is needed. The required power depends on the rotational speed and the torque acting on the rotor’s surface to overcome frictional forces. In this project, the power required to operate a rotor is characterized through a series of experiments in water and air, as well as at various rotational speeds. For this purpose, an existing scaled - down rotor sail model, equipped with a servo motor capable of 8000 RPM and 3.4 Nm was used. A mounting system was designed to support the rotor in a large fluid tank. The output RPM and torque data was collected during operation to determine the operating power of the rotor in each test. To examine the effects of fluid properties on the required torque, the temperature and pressure values were collected during each test. Through these experiments, a refined method is proposed in order to effectively predict power requirements for any rotor sail.