DLR Results from the Fourth AIAA Computational Fluid Dynamics Drag Prediction Workshop

Abstract

A summary about the DLR, German Aerospace Center results from the fourth AIAA Computational Fluid Dynamics Drag Prediction Workshop is presented. Compared to the investigations in the previous three workshops, the latest workshop had a stronger focus on drag and trim drag predictions as well as pitching moment calculations. Therefore, the new Common Research Model developed by NASA's Subsonic Fixed Wing Aerodynamics Technical Working Group and tested in NASA wind tunnels is used. It represents a state-of-the-art transonic transport aircraft configuration, and in contrast to the configurations previously taken, it includes an optional horizontal tailplane with three different tail settings. DLR has defined three objectives for its activities in the fourth drag prediction workshop. At first, investigations should identify solution accuracy and grid convergence behavior using prismatic element dominant grids for boundary-layer resolution in comparison to hexahedral element dominant grids. Second, the influence of turbulence models of increasing complexity is of interest regarding transonic pressure distributions and flow separations. Therefore, the one-equation turbulence model of Spalart and Allmaras, the two-equation Menter kω-shear-Stress-transport model, and the Speziale-Sarkar-Gatski/Launder-Reece-Rodi-ω Reynolds-stress model are applied. The third objective is to analyze what differences in the calculated pitching moments and horizontal tailplane trim angles can be expected for the Common Research Model with different horizontal tailplane settings when grids are regenerated for each setting or when they are deformed iteratively based on the grid for the initial setting. All investigations are performed with the grid generation software Solar and Centaur™ and the Reynoldsaveraged Navier-Stokes solver TAU. Recently, selected experimental data have been released by NASA and are used here for comparisons.

Summary Data from the Sixth AIAA CFD Drag Prediction Workshop: CRM Cases

“…Although this improvement is quite significant, the confidence level is not down to a low-enough level to compete with experimental methods. Documentation for these results can be found in summary papers [40,41] and in individual contributing papers [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] from two special sessions held at the 28th Applied Aerodynamics Conference in June 2010.…”

Summary of Data from the Sixth AIAA CFD Drag Prediction Workshop: CRM Cases 2 to 5

“…Although this improvement is quite significant, the confidence level is not down to a low-enough level to compete with experimental methods. Documentation for these results can be found in summary papers [40,41] and in individual contributing papers [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] from two special sessions held at the 28th Applied Aerodynamics Conference in June 2010.…”

Unsteady shock front waviness in shock-buffet of transonic aircraft

“…The model is a blend of the Speziale-Sarkar-Gatski (SSG) [37] and Launder-Reece-Rodi (LRR) [38] RSM turbulence models, with LRR-like behavior near-wall, and SSG-like behavior away from the wall [39]. The blending of the two models, originally in the SSG/LRR-ω model, has shown promising prediction of transonic aerodynamics in the DLR contributions to the AIAA CFD DPW [40,41]. The current model solves one equation for each Reynolds stress component, and an additional equation for a turbulent scale.…”