Olaf Brodersen

Data summary from Second AIAA computational fluid dynamics Drag Prediction Workshop

Results from the Second AIAA Drag PredictionWorkshop are summarized. The workshop focused on absolute and configuration delta drag prediction of the DLR, German Aerospace Research Center F6 geometry, which is representative of transport aircraft designed for transonic flight. Both wing–body and wing–body–nacelle–pylon configurations are considered. Comparisons are made using industry relevant test cases that include single-point conditions, drag polars, and drag-rise curves. Drag, lift, and pitching moment predictions from several different Reynolds averagedNavier–Stokes computational fluid dynamics codes are presented and compared to experimental data. Solutions on multiblock structured, unstructured, and overset structured grids using a variety of turbulence models are considered. Results of a grid-refinement study and a comparison of tripped transition vs fully turbulent boundary-layer computations are reported.

Abridged Summary of the Third AIAA Computational Fluid Dynamics Drag Prediction Workshop

Results from the Third AIAA Drag Prediction Workshop (DPW-III) are summarized. The workshop focused on the prediction of both absolute and differential drag levels for wing-body and wing-alone configurations that are representative of transonic transport aircraft The baseline DLR-F6 wing-body geometry, previously used in DPW-II, is also augmented with a side-of-body fairing to help reduce the complexity of the flow physics in the wing-body juncture region. In addition, two new wing-alone geometries have been developed for DPW-III. Numerical calculations are performed using industry-relevant test cases that include lift-specific and fixed-alpha flight conditions, as well as full drag polars. Drag, lift, and pitching-moment predictions from numerous Reynolds-averaged Navier-Stokes computational fluid dynamics methods are presented, focused on fully turbulent flows. Solutions are performed on structured, unstructured, and hybrid grid systems. The structured grid sets include point-matched multiblock meshes and overset grid systems. The unstructured and hybrid grid sets are composed of tetrahedral, pyramid, and prismatic elements. Effort was made to provide a high-quality and parametrically consistent family of grids for each grid type about each configuration under study. The wing-body families are composed of a coarse, medium, and fine grid, whereas the wing-alone families also include an extra-fine mesh. These mesh sequences are used to help determine how the provided flow solutions fare with respect to asymptotic grid convergence, and are used to estimate an absolute drag for each configuration.

Summary of the Fourth AIAA CFD Drag Prediction Workshop

Results of the Thrid AIAA Drag Prediction Workshop are summarized. The workshop is focused on the prediction of both absolute and differential drag levels for wing-body and wing-alone configuarations that are representative of transonic transport aircraft.

Summary of Data from the Fifth AIAA CFD Drag Prediction Workshop

Results from the 5, AIAA CFD Drag Prediction Workshop are presented. This workshop is focused on force/moment predictions for the NASA Common research wing-body configuration, including a grid refinement study and an optional buffet study. The article presents the summary of data of all participants.

Grid Quality and Resolution Issues from the Drag Prediction Workshop Series

The drag prediction workshop series (DPW), held over the last six years, and sponsored by the AIAA Applied Aerodynamics Committee, has been extremely useful in providing an assessment of the state-of-the-art in computationally based aerodynamic drag prediction. An emerging consensus from the three workshop series has been the identification of spatial discretization errors as a dominant error source in absolute as well as incremental drag prediction. This paper provides an overview of the collective experience from the worksho series regarding the effect of grid-related issues on overall drag prediction accuracy. Examples based on workshop results are used to illustrate the effect of grid resolution and grid quality on drag prediction, and grid convergence behavior is examined in detail. For fully attached flows, various accurate and successful workshop results are demonstrated, while anomalous behavior is identified for a number of cases involving substantial regions of separated flow. Based on collective workshop experiences, recommendations for improvements in mesh generation technology which have the potential to impact the state-of-the-art of aerodynamic drag prediction are given.

Summary of Data from the Fifth Computational Fluid Dynamics Drag Prediction Workshop

Results from the Fifth AIAA Computational Fluid Dynamics Drag Prediction Workshop are presented. As with past workshops, numerical calculations are performed using industry-relevant geometry, methodology, and test cases. This workshop focused on force/moment predictions for the NASA Common Research Model wing-body configuration, including a grid refinement study and an optional buffet study. The grid refinement study used a common grid sequence derived from a multiblock topology structured grid. Six levels of refinement were created, resulting in grids ranging from 0.64×106 to 138×106 hexahedra, a much larger range than is typically seen. The grids were then transformed into structured overset and hexahedral, prismatic, tetrahedral, and hybrid unstructured formats all using the same basic cloud of points. This unique collection of grids was designed to isolate the effects of grid type and solution algorithm by using identical point distributions. This study showed reduced scatter and standard deviation fr...

Advanced Turbulence Modelling and Stress Analysis for the DLR-F6 Configuration

The current DLR Computational Fluid Dynamics validation activities in the framework of the AIAA Drag Prediction Workshop are presented. Since the second workshop in 2003 advanced turbulence models have been integrated in the Reynolds-averaged Navier-Stokes solver FLOWer. The hybrid SSG/LRR-omega differential Reynolds stress turbulence model is presented, combining the Launder-Reece-Rodi (LRR) model near walls with the Speziale-Sarkar-Gatski(SSG) model further apart by applying Menters blending function F_1. Menters baseline omega-equation is exploited for supplying the length scale. The SSG/LRR-omega model is applied to the DLR-F6 aircraft configuration. Results are presented for a target lift computation at C_L = 0.500 and for lift, drag and moment coefficients in a range of incidence from -3 to 1.5 degrees. In addition to the validation activities the possibility of anew wind tunnel testing of the DLR-F6 was investigated. Because a test at a higher Reynolds-number is of interest the mechanical strength of the model was analysed using the Finite-Element-Method software ANSYS.

Airbus, ONERA, and DLR Results from the Second AIAA Drag Prediction Workshop

The results from DLR, Airbus, and ONERA from the Second AIAA Computational Fluid Dynamics Drag Prediction Workshop are presented. The lift, drag, and pitching moments are calculated for the DLR-F6 configuration at transonic flow conditions by solving the Reynolds-averaged Navier-Stokes equations on structured as well as on unstructured, hybrid grids.

Summary of the Fourth AIAA Computational Fluid Dynamics Drag Prediction Workshop

Results from the Fourth AIAA Drag Prediction Workshop are summarized. The workshop focused on the prediction of both absolute and differential drag levels for wing–body and wing–body/horizontal-tail configurations of the NASA Common Research Model, which is representative of transonic transport aircraft. Numerical calculations are performed using industry-relevant test cases that include lift-specific flight conditions, trimmed drag polars, downwash variations, drag rises, and Reynolds-number effects. Drag, lift, and pitching moment predictions from numerous Reynolds-averaged Navier–Stokes computational fluid dynamics methods are presented. Solutions are performed on structured, unstructured, and hybrid grid systems. The structured-grid sets include point-matched multiblock meshes and overset grid systems. The unstructured and hybrid grid sets comprise tetrahedral, pyramid, prismatic, and hexahedral elements. Effort is made to provide a high-quality and parametrically consistent family of grids for each g...

Investigation of Aeroelastic Effects on the NASA Common Research Model

Static fluid-structure coupled simulations were performed on NASA’s Common Research Model to assess the influence of aeroelastic effects on the numerical prediction of the overall aerodynamic coefficients and wing static pressure distributions. The numerical results of both rigid steady-state computational fluid dynamics and static aeroelastic coupled simulations were compared to the experimental data from wind tunnel test campaigns at NASA’s National Transonic Facility and the NASA Ames Research Center’s 11-Foot Transonic Wind Tunnel Facility. Coupled analyses were performed using an in-house simulation procedure built around the German Aerospace Research Center’s flow solver TAU and the commercial finite element analysis code NASTRAN®. The results show a considerable reduction of deviations between the computational results obtained during the fourth and fifth AIAA Computational Fluid Dynamics Drag Prediction Workshops and the measured data when aeroelastic wing deformations are taken into account.