Wind-tunnel wall interference studies at high subsonic speeds.

Abstract

With the introduction of the ventilated test section in wind tunnels for high-speed subsonic and transonic testing, new procedures have been sought to extend the classical wall interference methods for correcting model test data. Because of the complex nature of the interferences, a satisfactory general analytical solution to the interference problem for ventilated walls is yet to be achieved. In this program, a solid-wall test section and several ventilated test section configurations were used to investigate experimentally and evaluate the wall interference on four force models. The model force data generated in the so lid-wall test section were corrected by the application of classical theoretical wall corrections and used as a basepoint for evaluating the data obtained in the ventilated test sections. One of the force models used has been tested in the NASA/Langley Research Center 8-ft transonic pressure tunnel, and substantial data were available for comparison purposes with data generated in the North American Rockwell Corporation Trisonic wind tunnel. The result of this program was the development of a porous-slot test section having a wall porosity of 5.7%. This test section design produces a wall interference-free environment for moderately sized models up to 1% blockage with wing span to test section width ratios as large as 0.71.