An Experimental Investigation of an Airfoil Optimized for High Lift,

摘要

An experimental investigation was performed on an airfoil optimized for maximum lift. The airfoil shape was designed from an optimum pressure distribution using a calculus of variation technique. The purpose of the investigation was to evaluate the validity of the method of design of the airfoil, and to determine what type of differences existed, if any, in the theoretical and experimental results. The airfoil was tested at a Reynolds number approximating the design Reynolds number of 1,000,000. The airfoil angle of attack was varied in 2 deg increments from 0 deg to 12 deg. At each angle of attack, three blowing rates were used for slots installed on the model end plates. Data recorded for each test run consisted of the airfoil static pressure distribution, static and total pressures from a wake traverse, atmospheric pressure and temperature, and the tunnel temperature. Normal and chordwise force coefficients were obtained from the static pressure data. Using the true angles of attack from potential flow theory, lift and pressure drag coefficients were found. Total drag coefficients were found from the wake traverse data. Increased blowing caused the experimental pressure coefficient distributions at higher angles of attack to come into close agreement with the theoretical pressure coefficient distribution, and resulted in increased lift and decreased drag. True two-dimensional flow was not maintained at the higher angles of attack, due at least in part to the test installation. (Author)