Effect of wind tunnel wall porosity on the flow around an oscillating airfoil at transonic speeds

The effect of porosity in oscillating situations (to the authors' knowledge, for the first time) on a supercritical airfoil (SC0410) has been experimentally investigated. Tests have been carried out in an open circuit suction-type wind tunnel at a free stream Mach number of M = 0.80. Both static and dynamic (pitching) tests have been carried out on the mentioned airfoil. The oscillation frequency for the unsteady tests has been set to 3 and 6 Hz. The amplitude of frequency is 1 deg. The effect of porosity has been surveyed on the magnitude of pressure fluctuations, phase shift, and lift coefficient loop. The investigations show that increasing porosity in the test section of transonic regime, contrary to the impression, does not necessarily improve results. (C) 2017 Sharif University of Technology. All rights reserved.