Correction of 2D transonic wind tunnel wall interference using the porosity parameter method

The porosity parameter method based on the linear potential flow theory was employed to study the effect of transonic wind-tunnel wall interference, on a configuration of two-dimensional perforated walls. Experiments were carried out with a NACA0012 airfoil whose surface pressure distributions were obtained at Mach numbers from 0.3 to 0.8 at angles of attack from -2° to 11°. Subsequently, the lift coefficients of the airfoil were calculated by integrating over the pressure distribution data measured. By comparing the lift coefficients obtained with the reference data given in the literature which was considered as interference free, one was able to follow the porosity parameter method mentioned and deduced the parameter values characterizing the interference effect associated with the present wind tunnel. As a result, corrections on the lift coefficients could be made. As found, the porosity parameter method was able to adjust the lift coefficients measured to the reference data up to Mach number 0.7, and at angles of attack up to 5° approximately. At higher Mach number or higher angle of attack, this method can not give satisfactory result due to non-linearity of the flow.