Thick-section airfoil for windmill rotor blade has front, top and rear portions forming arc of circle and flat underside at angle to incident airflow making D-section

摘要

The flat bottom surface (N) may be set at an angle of e.g. 30 degrees to the incident air stream (R). The corners (A,B) at the front and rear of the flat bottom surface are sharp. A vortex (Y) forms at the front corner, near the leading edge stagnation point (X). Air flows over the front (M) and rear (P) parts of the top surface past the top profile point (D) and the rearmost point (C). Air coming off the sharp corner at the end of the undersurface forms a vortex (Z) near the rear stagnation point on the circular curved profile (O).