The effect of laminar separation bubbles on the surface pressure distribution and aerodynamic force characteristics of a horizontal axis wind turbine airfoil is studied numerically. The NREL S809 airfoil for stall-controlled horizontal-axis wind turbines is analyzed at a chord Reynolds number of For all flow conditions involving laminar separation in the present study, bubble-induced vortex shedding is observed. This flow phenomenon causes significant oscillations in the airfoil surface pressures and, hence, in the airfoil-generated aerodynamic forces. The computed time-averaged pressures compare favorably with wind-tunnel measurements.
Issue Section:
Technical Papers
Keywords:
wind turbines,
bubbles,
aerodynamics,
laminar flow,
flow separation,
vortices,
wind tunnels
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