On enhancing the energy capture in a downstream rotor tidal energy converter by using pylon fairings

Tidal energy converters where the flow encounters an upstream pylon prior to the rotor are known to create a velocity deficit at the rotor plane, affecting its power capture. In addition, the pylon wake escalates load fluctuations on the rotor, increasing the fatigue loading on the blades. The ongoing collaboration between Lehigh University and Verdant Power, Inc. aims to explore the effects of various fairing shapes on the pylon wake characteristics. Pylons tested employed downstream fairings composed of straight, convex, and concave plates. A pylon with fairings both upstream and downstream, referred to as the Double Fairing was also developed. All designs were tested at Re = 2×10⁴, two levels of elevated turbulence mimicking tidal energy sites (6% and 18%, generated using an active grid) and two yaw states; 0^o and 15°. Of all tested fairings, the double fairing appeared to be the most effective, with a yawed double fairing further improving power capture by 2.25%. Elevated turbulence was found to increase power capture by 1%. Tests at Re = 6×10⁴ are underway to better stimulate boundary layer transition and will also be presented at the conference.