But in the same articles you se that on a well-designed airfoil the air remains attached to the trailing edge or very near it, where the airfoil is narrowing down to a sharp point. So detached airflow creates only a very narrow region of vacuum. Reducing that provides little reduction in drag - probably nowhere near enough to pay for the extra drag of the dimples.
(I wonder if there's something you can do with dimples to improve attachment on part of the cycle of a drag-type VAWT that would give you a net gain.)[ Parent ]
