Project Summary
Exploring the integration of a passive drag-reduction technique on Flettner rotor sails to enhance the aerodynamic efficiency of wind-assisted propulsion systems. The ultimate aim is to reduce vessel fuel consumption and, consequently, emissions by optimising both the surface pattern along the rotor and its configuration in terms of the shape and position relative to rotor height (i.e., near-ground region, transition zone, and upper free-stream region). Experimental studies will be carried out in the University of Strathclyde’s Fully Turbulent Flow Channel to assess the performance of different drag reduction techniques under varying flow conditions. The findings will inform high-fidelity numerical simulations aimed at quantifying the effectiveness of the concept. By examining the influence of surface pattern on flow separation, lift generation and drag reduction, the project seeks to deliver a proof-of-concept upgrade to wind-assisted propulsion systems. The outcome will be a validated solution for retrofitting or newbuilding applications, integrating a passive drag-reduction technique initially into rotor sails to extend their operational range and enhance efficiency, particularly under light-wind conditions where current systems are less effective. This innovation aligns with the UK’s Maritime Decarbonisation Strategy and directly supports Net Zero targets by improving wind energy capture, reducing reliance on main propulsion, and enabling sustainable vessel operations.
Project Achievements
The project combined laboratory experiments, advanced computer simulations, and industry engagement. Dimpled surface patterns were designed and tested in a controlled flow facility to measure their effect on aerodynamic performance. High-fidelity Computational Fluid Dynamics (CFD) simulations were then used to model how these patterns influence lift, drag, and wake behaviour of a rotor sail. Results from experiments and simulations were cross validated to ensure reliability. The team also engaged with shipping industry partners to understand real-world operating conditions and practical implementation requirements. This integrated approach enabled the concept to progress from early-stage research to validated laboratory-scale performance.
Conclusions
The project demonstrated that optimised surface patterns can improve aerodynamic performance, increasing the potential energy savings from rotor sails. Enhanced efficiency means reduced engine load, lower fuel consumption, and decreased greenhouse gas emissions. By improving the reliability of wind-assisted propulsion, the innovation strengthens the business case for wider adoption of renewable wind technologies in shipping. Beyond maritime applications, the findings may also benefit other industries where airflow and surface optimisation are important. The project contributes to the UK’s maritime decarbonisation goals and supports the transition toward more sustainable transport systems.
Next Steps
The next phase will focus on scaling the concept toward real-world application. Model-scale testing in wind tunnel facilities will validate performance under more representative conditions. This will be followed by collaboration with industry partners to assess manufacturability and explore ground-based and onboard trials. Further funding will support progression to higher Technology Readiness Levels (TRL 6-7), bringing the solution closer to commercial deployment. By combining academic expertise, industrial collaboration, and structured validation, the project aims to translate laboratory success into practical impact at sea.
