Numerical study into the effects of effective angle of attack motions on energy extraction performance of parallel foils

The effects of different effective angle of attack motions on flapping foil are considered. Energy extraction characteristics of parallel foils with combined plunging and pitching motions at multiple working conditions are systematically analyzed. The energy extraction processes of dual foil at different effective angle of attack motions and reduced frequencies are simulated, respectively. In the range of parameters discussed in this paper, the increase of Ke improves the energy extraction performance of foil effectively. Every effective angle of attack motion has a frequency which can obtain the optimal extraction performance. The optimal energy extraction working condition is Ke = 2 and k = 0.8, where the extraction efficiency of dual foil achieves 25.8%. The synchronicity of the aerodynamic lift and the plunging motion is increased with increase in Ke. This paper provides a significant reference to the further study and popularization in engineering practice of parallel foils energy extraction