Wind Tunnel Low-Speed Tare and Interference Corrections: CFD vs Test Results - The Supersonic Configurations (SCALOS) Cases

The traditional "3-step" combination of model and mounting set-ups for wind tunnel aerodynamic support tare and interference (T&I) quantification can be time-intensive and expensive. Methods which apply generic "support tare" corrections for a given facility’s mount and tunnel, independent of model configuration, can result in significant data reduction inaccuracies due to configuration-specific aerodynamic interferences between the support system and the model. The slender models tested for the SCALOS investigation combined large wing areas, low aspect ratio, and high leading edge sweep, which created flow disturbances in the tunnel that were significantly different from that of conventional reference models used by the tunnel to establish its simplified generic adjustments. This paper explores the usefulness of CFD-based methods for the establishment of T&I corrections, which could prove more cost-effective and timely than traditional in-tunnel measurements, particularly when multiple model or support types are employed in the same entry. When compared to a CFD simulation of the wind tunnel model without a support system, it was found that the "3-step" T&I method was able to match the changes in induced drag and the changes in lift experienced by the model. The correction for pitch was also matched well. For sideslip angles, for both lift and drag the "3-run" T&I method got the magnitude right, but the curves produced were not as smooth as some of the other methods. The "3-step" T&I method was successfully verified for supersonic configurations at low speeds using CFD. The results of the study also allow assessment of the accuracy with which CFD can match wind tunnel test results of each of the steps of the "3-step" T&I process. For future applications and efficiency in testing, replacing the wind-tunnel T&I process with CFD-based T&I corrections may be considered.