From model-scale to full-scale: Optimizing buoy geometry for enhanced energy conversion in PA-WECs
Ali Azam, Ammar Ahmed, Attia Qammar, Asad Naeem Shah, Zutao Zhang, Zeqiang Zhang, Touqeer Aslam, Shoukat Ali Mugheri, Minyi Yi, Xing Tan, Minyi Yi, Xing Tan
Abstract
This study optimizes buoy geometry for Point Absorber Wave Energy Converters (PA-WECs) by bridging model-scale and full-scale designs, aiming to enhance energy conversion efficiency for wave energy harvesting. Two floating structure geometries, cylindrical (Cyl) and top-shaped axisymmetric (AS), were analyzed by optimizing key design parameters (diameter, draft, volume, and mass) to maximize energy conversion efficiency. Initially, numerical simulations were conducted using ANSYS AQWA for the model scale, followed by experimental validation through 1:25 scaled wave tank tests. The next phase involved the optimization framework of floating buoys at fixed parameters (Algorithm i) and variable parameters (Algorithm ii) to identify the optimal buoy design. Subsequently, full-scale modeling was performed to evaluate hydrodynamic performance using frequency- and time-domain analyses. Finally, FFT analysis identifies key performance parameters, including resonance bandwidth, optimal frequency range, and significant wave height, for maximizing energy absorption. The results demonstrate that the AS buoy outperforms the Cyl buoy, achieving a higher resonance amplitude and enhanced energy capture efficiency at full scale. Specifically, the AS buoy achieved a higher RAO of 6.252 m/m, compared to 5.789 m/m for the Cyl buoy, indicating superior resonance and energy absorption performance. Additionally, the AS buoy captured an absorbed power of 24,779.83W, reflecting a 10.67 % increase over the Cyl buoy (22,136.51W) and a 12.33 % increase in capture width compared to the Cyl buoy. Finally, Fast Fourier Transform (FFT) analysis identifies the optimal energy capture frequency range as 0.02 Hz–0.06 Hz, with the AS buoy exhibiting larger power absorption amplitudes. Despite having a narrower resonance bandwidth (0.06217 Hz) compared to the Cyl buoy (0.0683 Hz), the AS buoy demonstrated superior power absorption and capture width, especially under larger significant wave heights (>1.5 m). These findings highlight the AS buoy's potential for real-world applications aligning with UN SDGs 7 and 14 goals for the global clean energy transition.