Numerical Investigation of Aerodynamic Interactions between Rigid Sails Attached to Ship

Abstract

As part of the strategy to achieve net-zero Greenhouse Gas (GHG) emissions in international maritime shipping, there is ongoing exploration into the use of wind propulsion systems as auxiliary ship propulsion devices. When considering a rigid sail as the wind propulsion system, evaluating the performance of a single sail is relatively simple. However, assessing the performance of multiple sails is more challenging due to the interference between the sails and between the sails and the hull. In this study, the thrust characteristics of two rigid sails attached to a ship are investigated by using Computational Fluid Dynamics (CFD). This includes considering the interference effects between the sails themselves and between the sails and the hull. The research reveals the innovative optimized angle of attack for maximizing thrust under tailwind conditions. At 150° in relative wind direction, the best performance is achieved with a low angle of attack on the fore side sail and a high angle of attack on the aft side sail. At 180° in relative wind direction, a high angle of attack on the fore side sail and a low angle of attack on the aft side sail yield the best results. Here, a “low” angle of attack means that the lift force is greater than the drag force, while a “high” angle of attack means the drag force is greater than the lift force. In this study, the force in the ship’s forward direction is only focused on optimizing the angles of attack of the two sails. However, the side forces caused by the sails are also significant for the ship’s sailing conditions. Therefore, future work will involve optimizing the angles of attack under drifting conditions.

Keywords

• wind propulsion
• wind powered ship
• wing sail
• CFD
• aerodynamics