Panel code estimates of wind tunnel wall and support interference effects on the HSCT

Abstract

The Boeing internal version of the higher order panel code PANAIR, known as A502, was used to compute wall and model support interference effects on a Boeing/NASA High Speed Civil Transport, or HSCT, configuration. Computational results were compared to experimental data acquired on the 6% HSCT low speed model in the NASA-Langley 14'x22' wind tunnel. The numerical results indicated the influence of the model supports on the lift to be greater than that of the walls at low angles of attack and to decrease very slowly with incidence, in contrast to the increasing wall effect. The swept strut support had a much larger impact on the lift than the simple post mount and the impact of the model support systems on the lift curve slope was determined to be negligible. The magnitude of the induced drag correction from the walls and model supports increased with incidence. Pitching moment behavior indicated that the strut and post support influence decreased with angle of attack as wall influence increased. Interdependency between the walls and mounting system impact on the aerodynamic loads was observed. Application of the A502 corrections to experimental data obtained in the NASA 14' x 22' tunnel using different model supports reduced the differences between the experimentally measured lift curves. The results of this study indicated that while a panel code such as PANAIR cannot be used to predict absolute aerodynamic load levels, it can be used to estimate model support interference trends and increments and to correct differences in measured data.