Supersonic Configurations at Low Speeds (SCALOS): CFD Aided Wind Tunnel Data Corrections

Star-CCM+ RANS CFD simulations were used to investigate the effects of the model support system and test section walls on a double-delta wing, representative of long-range supersonic configurations, in the low-speed University of Washington’s Kirsten Wind Tunnel in an effort to improve current wind tunnel test corrections for such configurations. The work is a part of the NASA SCALOS project (Supersonic Configurations at Low Speeds). The differences between the SCALOS configurations and the configurations that were used in the past to establish wind tunnel corrections raised questions about the adequacy of the "standard" corrections in the SCALOS case. Simulation-derived support corrections were validated using information for past wind tunnel models and their support corrections. New model support corrections were computed for the new family of configurations using CFD and wind tunnel data. Wall effects corrections were also evaluated via CFD, and results compared well to classical corrections traditionally applied by the Kirsten Wind Tunnel. The pitching moment curve slope was underpredicted, however, with CFD simulations. Proceeding to study full configurations, engine nacelle form factors were also calculated to add new nacelle internal duct drag corrections to the wind tunnel data. All CFD derived corrections were applied to past uncorrected wind tunnel data, compared to data with KWT’s standard corrections, and to new CFD simulations of the models in freestream conditions. Applying the CFD-derived wall effects and CFD-adjusted T&I corrections did improve the correlation between the wing-alone test data and free flight CFD analysis. More work is necessary to understand the correlations between test data and CFD for full configurations in free flight.