Numerical Investigation of Energy Harvesting Wingtip-Mounted Propellers

Energy harvesting propellers were numerically investigated with regard to their aerodynamic performance and their potential application for aircraft. First, an in-depth study on isolated rotors was carried out. Two different modes of energy harvesting propellers were considered and compared: the windmilling and opposite pitch modes. The opposite pitch mode was able to generate larger forces and also to harvest more energy, reaching an energy harvesting efficiency of 25.24% compared to 17.58% for the windmilling mode. A reference turbine was created for comparison by inverting the twist distribution of the original propeller geometry. It was able to harvest 46.22% of the energy. In a second study, installation effects for the energy harvesting rotors at the wingtip-mounted position were investigated using the actuator disk model. For the rotors mounted in a tractor configuration, a significant drop in lift (up to [Formula: see text]) was observed due to flow separation at the wingtip. With a pusher configuration, a decrease in lift was also observed (although smaller, up to [Formula: see text]), caused by a pressure increase upstream of the rotors, which also caused local drag decreases at the wing. The influence of the (wing) angle of attack and the rotor diameter was also examined in this study.