Separation blockage-correction method for the airfoil of a wind turbine blade

A new blockage-correction method for the separated flows around the airfoil of a wind turbine blade was developed for the wall interference correction of the closed test-section wind tunnel. A wind tunnel test was performed for the airfoil at an angle-of-attack range of 0–180°. The freestream velocity was 15 m/s, which corresponds to a Reynolds number of 2.3 × 105 based on the chord. Then a blockage correction for the separated flows was obtained with respect to the multiplication of the blocking area and the separation drag coefficient based on the test. The present method was validated by comparing the corrected results with those of the existing classical and measured-boundary-condition methods. The results of the classical method are similar to those of the measured-boundary-condition method at the attached flow region; however, at high angles of attack, the difference in the corrected results between the classical and MBC methods becomes significantly large. The present method is in good agreement with the measured-boundary-condition method, enabling better wall corrections than the classical method in post-stall region.