Experimental Investigation of Unsteady Surface Pressure Characteristics on a Two-dimensional Airfoil under Turbulent Inflow Conditions

Abstract

Unsteady surface pressure measurements were conducted on an isolated airfoil exposed to either low- or high turbulence inflow conditions. The tests were performed in the NUAA's (Nanjing University of Aeronautics and Astronautics in China) 3m low speed wind tunnel. The airfoil was a 1.2m chord (two dimensional) NACA 0012 standard airfoil. Measurements were taken for free stream velocities of 41m/s and 30m/s and at angles of attack of 0, 5, 10, 15 degrees. A grid was used to achieve an almost homogeneous turbulent flow field with a turbulence intensity of 5.3% and an integral length scale of 0.049m at a free stram velocity of 30m/s. Unsteady surface pressure spectra were determinded on the suction side (upper side) at positions corresponding to 8.7%, 15%, 26%, 50% and 70% of the airfoil chord as well as at a 15% position on the pressure side (lower side). The data were taken by means of flush-mounted 1/4"-diameter condenser (pressure type) microphones.