Assessment of sidewall interference in a two-dimensional transonic wind tunnel

Effects of test section sidewalls have been investigated in a two-dimensional transonic wind tunnel. The facility has recently been modified to improve the flow two-dimensionality for airfoil testing. A procedure where two corrections for top and bottom wall interference and for sidewall interference are combined is applied to data obtained in the modified facility. Satisfactory agreement with free-air computations and other experimental results is presented for two different airfoils. The applicability of sidewall corrections to various configurations of airfoil model is then discussed. To reduce threedimensional effects, a device for removing sidewall boundary layers has been installed. The significant validity of the device, however, has not been confirmed because of Mach number nonuniformity. These results suggest that the optimum experimental arrangement for transonic airfoil testing should be reconsidered for each wind tunnel to provide truly two-dimensional data.