Effect of Frequency on the Performance of a Section of a Wind Turbine Blade
A series of low speed wind tunnel tests on a section of a 660 Kw wind turbine blade were conducted to examine the effects of frequency on its performance characteristics. The airfoil profile was NACA 63-617 and selected from the mid section of the turbines’ blade radius which generates the main part of the blade torque. Dynamic tests were performed for three cases of prestall, stall and post stall conditions. The domain of oscillations was 5 degrees and at 3 mean angles of attack which is 5, 10 and 18 degrees. The model was tested for four Reynolds number and for various reduced frequencies. In downstroke motion, it was obvious that oscillation had positive effect on aerodynamic characteristics at low angles of attack but negative effect happened post stall angles of attack that reduced lift coefficient. This phenomenon was in conflict with upstroke motion.
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