Assessment of Hybrid Delta Wing Vortex Flow Investigation – Part I at Subsonic Conditions

The dependencies of numerical simulations regarding grid sensitivity and modelling error for vortex dominated flow need particular investigation. In this study, an extensive investigation on the grid sensitivity is conducted and the influence of different turbulence closures is analyzed. For this purpose, a triple-and a double-delta-wing configuration are considered. In a collaboration between the French National Centre for Scientific Research, the Centrale Nantes Engineering School and the Technical University of Munich, simulations were conducted to identify grid and turbulence closure sensitivities. For the grid sensitivity, a comparison of the global force and moment coefficients and of the local flow in the vortex core is shown. From this, it can be concluded that the local flow is more sensitive to grid adaptation than forces and moments. Furthermore, the double-delta-wing configuration seems to be more affected by grid sensitivity. The comparison of (formula presented) shear stress model, delayed detached eddy simulation and different grids and background closures indicates a lower influence of grid sensitivity to delayed detached eddy simulations than to (formula presented) shear stress models. A grid convergence represents an important parameter but for vortex dominated flows, it can only be achieved by a local convergence for the vortex core flow is of primary importance as vortex core flow characteristics strongly determines the accuracy of the moment prediction.