Assessment of RANS Turbulence Models for Strut-Wing Junctions

Abstract

Multidisciplinary Design Optimization (MDO) studies show the Strut/Truss Braced Wing (SBW/TBW) concept has the potential to save a significant amount of fuel over conventional designs. For the SBW/TBW concept to achieve these reductions, the interference drag at the wing strut juncture must be small compared to other drag sources. Computational Fluid Dynamics (CFD) studies have concluded the interference drag is small enough for the TBW concept to be practical. However, the turbulence models used in these studies have not been validated for transonic, high Reynolds number, junction flows. This study intends to assess turbulence models by comparing drag and surface streamlines obtained from experiment and CFD. The test model is a NACA 0012 fin at Mach number of 0.75 and a Reynolds number of 6 million with varying angle of attack. The CFD analysis includes both the fin and tunnel test section. The main turbulence model tested is the k-w Shear Stress Transport model. The fin is tested at different Mach numbers and inlet conditions to account for experimental variations. The study shows the CFD over predicts separation. The reasons for this discrepancy is likely the turbulence models employed.