Vortex Shedding Lock-In due to Pitching Oscillation of a Wind Turbine Blade Section at High Angles of Attack

Figure 9

Instantaneous horizontal velocity showing the flow reattachment point on the leading edge for (a, b) and (c, d) on their max and min pitching position (); flow velocity left-to-right (in pink) and flow velocity right-to-left (in blue).

(a) ; upper position

(b) ; lower position

(c) ; upper position

(d) ; lower position