Retrofitting of Flettner Rotors – Results From Sea Trials of the General Cargo Ship “Fehn Pollux”

Abstract

In 2018, a German- Dutch project consortium under the scientific direction of the Emden/Leer University of Applied Sciences retrofitted and commissioned the latest rotor development of the Eco-Flettner type on the test ship Fehn Pollux of the Leer-based shipping company Fehn Ship Management. Main design features are both upper and lower endplates with large diameter for improved aerodynamic performance and modular manufacturing. The retrofitting concept is groundbreaking in terms of easy transferability to other ships. Upscaling to a significant share of the world merchant fleet could make a substantial and realizable contribution to climate protection in the short term and potentially reduced transport costs in the long term. The most frequently asked question in connection with modern sail drives is about the performance potential and the associated fuel savings. Transparent performance data is required to enable an economic prognosis for the use of Flettner rotors on ships. The Faculty of Maritime Sciences at Emden/ Leer University of Applied Sciences has developed an automatic control and monitoring system for Flettner rotors that also records extensive operating and environmental data. The data shows that all previous assumptions and model calculations are basically correct. With regard to the performance potential, the first series of measurements show even higher rotor forces compared with model calculations. This is a further benefit for Flettner rotor efficiency and could help the technology achieve a breakthrough as a building block for low-emission shipping.

Performance Prediction Program for Wind-Assisted Cargo Ships

“…With the aim to improve the interpolation accuracy and, therefore, the model predictions, wind tunnel test results from the retrofitted cargo ship Fehn Pollux (Vahs, 2019) are also included in this rotor sail model data set. To predict the aerodynamic loads of any rotor sail within the valid configuration range, the discrete data is fitted with a multi-dimensional spline interpolation, integrated into the FS-Equilibrium software.…”