Abstract
The essentiality to increase the use of renewable energy sources is driving research in ocean wave and current energy technologies. This study introduces the development of ‘Aurelia WINO’, a prototype of a floating wave energy converter (WEC), designed at Kiel University of Applied Sciences. The system, based on the principle for a point absorber, was constructed in partnership with the maritime industry. To facilitate safe transport to the designated test location near the FINO 3 research platform in the German North Sea, experimental towing trials were conducted using a 1:20 scale model with equivalent floating characteristics.
The experimental setup involved varying length ratios of the towing lines under different current and wave conditions, conducted in the marine flow lab at the Institute of Naval Architecture and Maritime Technologies. The goal was to identify a stable towing configuration that minimizes rolling and tilting. Results from trials indicated that a line ratio of 1.05 yielded the smallest mean tilt and roll angles, especially at current velocities up to 0.2 m/s. Numerical models and analytical calculations supported these experimental findings, demonstrating that the main force on the towing lines was current-induced, with waves contributing additional load.
The study concludes that an adjustable towing configuration with a typical line ratio of 1.05 is optimal for the prototype scale, ensuring minimal tilt and roll angles. This configuration can be adjusted in real-time during transport based on vessel speed, wave height and tidal currents. The integration of numerical, analytical and experimental approaches confirms that analytical calculations suffice for designing towing equipment. However, experimental and numerical analyses are critical for identifying limits on rolling and tilting. This research lays the foundation for scalable towing strategies for full-scale WEC deployment, contributing to the global advancement of marine renewable energy solutions.