Energy extraction performance of motion-constrained tandem oscillating hydrofoils

An energy extraction technology based on motion-constrained tandem oscillating hydrofoils is presented in this paper. The turbine for extracting energy from the flow field is designed and built based on the measured frequency and energy extraction performance analysis of motion-constrained tandem oscillating hydrofoils. The instantaneous rotating speed and torque for the output shaft of the turbine are measured using a torque meter to determine the instantaneous power extracted by the turbine. Experimental results for this energy extraction turbine show that the optimal reduced frequency for both a single oscillating hydrofoil and tandem oscillating hydrofoils is about 0.1 and that the cycle-averaged energy extraction efficiency of the turbine with motion-constrained tandem oscillating hydrofoils reaches 29.2%. Published by AIP Publishing.