The maximum energy extraction efficiency of an airfoil and its optimum operation conditions in aero/hydro kinetic energy converters

In this study, the energy extraction from flow streams by means of airfoil is investigated. The first step is consideration of ability of energy extraction with respect to kinematics parameters. The maximum energy extraction for different airfoils with respect to appropriate Tip Seed Ratio (TSR) is evaluated. It is shown that the maximum power coefficients are in higher TSR. It is worthy to mention that the maximum power extraction by airfoil is not the efficient operation point because ability of airfoil for energy extraction is limited by ratio of foil chord to operation span. Furthermore, it is shown that the maximum energy extraction efficiency by airfoil is 49.9% and the possible range of optimum TSR is form 0.5 to 1.5.