DLR-F11 High Lift Configuration Research Articles

Mesh deformation on 3D complex configurations using multistep radial basis functions interpolation

The Radial Basis Function (RBF) method with data reduction is an effective way to perform mesh deformation. However, for large deformations on meshes of complex aerodynamic configurations, the efficiency of the RBF mesh deformation method still needs to be further improved to fulfill the demand of practical application. To achieve this goal, a multistep RBF method based on a multilevel subspace RBF algorithm is presented to further improve the efficiency of the mesh deformation method in this research. A whole deformation is divided into a series of steps, and the supporting radius is adjusted in accordance with the maximal displacement error. Furthermore, parallel computing is applied to the interpolation to enhance the efficiency. Typical deformation problems of the NASA Common Research Model (CRM) configuration, the DLR-F6 wing-body-nacelle-pylon configuration, and the DLR-F11 high-lift configuration are tested to verify the feasibility of this method. Test results show that the presented multistep RBF mesh deformation method is efficient and robust in dealing with large deformation problems over complex geometries.

Flow Analysis of the DLR-F11 High-Lift Model Using the Galatea-I Code

The academic computational fluid dynamics code Galatea-I is used in this study for the prediction of the flow over the DLR-F11 high-lift configuration, presented in the Second AIAA High-Lift Prediction Workshop. The proposed solver employs the Reynolds-averaged Navier–Stokes equations, modified appropriately by the artificial compressibility method and combined with the shear-stress transport turbulence model to account for the simulation of incompressible turbulent flows. Attention is mainly directed toward the assessment of the alternative, artificial compressibility methodology against such test cases because the majority of the workshop participants had implemented compressible Reynolds-averaged Navier–Stokes codes with preconditioning matrices instead. To this end, the flow at various angles of attack over the DLR-F11 aircraft model is studied, whereas the obtained results are compared to the available experimental data as well as simulation results produced by reference solvers. A satisfactory agreement is reported, demonstrating the proposed methodology’s potential to accurately predict such complex flows and adapt to uncommon areas of use.

Detached-Eddy Simulation of a Wide-Body Commercial Aircraft in High-Lift Configuration

Numerical prediction of the aerodynamic properties of high-lift configurations has become an important topic for the computational fluid dynamics community in the last years. The present paper shows and discusses a numerical study of the DLR-F11 high-lift configuration that was used as a model reference in the Second High-Lift Prediction Workshop, organized by the AIAA in 2013. Case 1 of the workshop was simulated with the commercial software ANSYS Fluent v14.5, using the Spalart–Allmaras (fully turbulent Reynolds-averaged Navier–Stokes) model. Numerical results showed good agreement for angles of attack lower than 18 deg; however, above this value, simulations were not accurate enough near to . To study the influence of the turbulence model in the dynamics of the flow and the numerical prediction of the aerodynamic properties near to , the original grids were adapted and a hybrid Reynolds-averaged Navier–Stokes/large-eddy simulation model (detached-eddy simulation based on Spalart–Allmaras) was used. Numerical results for the detached-eddy simulation showed a small change in the prediction of the aerodynamic properties near to , as well as improved vorticity resolution in the wake.

OVERFLOW Analysis of the DLR-F11 High-Lift Configuration Including Transition Modeling

The OVERFLOW Reynolds-averaged Navier–Stokes solver has been used to predict the aerodynamic characteristics of the DLR-F11 high-lift configuration for the conditions prescribed for the second AIAA Computational Fluid Dynamics High-Lift Prediction Workshop. A grid-convergence study is performed for the geometry with the slat and flap brackets excluded. The influence of including the brackets in the computational geometry is considered, and the effects of varying Reynolds number are analyzed for the brackets-on configuration. An optional case for the workshop, but a focus of this paper, is the inclusion of laminar–turbulent transition in the solutions. Two computational-fluid-dynamics-compatible transition models are used for the analysis, and their behaviors are discussed. A turbulence-model-verification study, which was also an optional case for the workshop, is included.

Numerical Investigations of the High-Lift Configuration with MFlow Solver

Numerical investigations of the DLR F11 high-lift configuration from the 2nd AIAA High-Lift Prediction Workshop are performed with the in-house solver MFlow. The solver is based on a cell-centered finite-volume method and is capable of handling various element types. Hexahedral grids and hybrid grids are used in the simulations. Grid-convergence properties, polar line, and pressure distributions are analyzed and compared with experimental data. A nearly linear convergence property is achieved with grid refinement for configuration 2, which is the most simplified configuration of the experiment model. When including slat and flap brackets (configuration 4), results are improved compared to the simplified configuration. However, delayed stall and larger maximum lift coefficient compared with experiment are found for high-Reynolds-number computations. The rotation correction of Spalart–Allmaras model does not lead to obvious improvement at high angles of attack. The effects of Reynolds number are qualitatively captured by the simulations. The inclusion of pressure-tube bundles causes loss of lift near stall and has little influence on predictions at lower angles of attack. The solver shows good agreement with experiment at lower angles of attack, but more attention is needed at angles of attack near and beyond stall.

Improved Point Selection Method for Hybrid-Unstructured Mesh Deformation Using Radial Basis Functions

In this paper, an efficient mesh deformation technique for hybrid-unstructured grids, based on radial basis functions, has been developed. The principle procedure adopted for this scheme can be divided into two steps. First, a series of radial basis functions are constructed by an interpolation method according to the displacements of moving boundary points. Later, the displacements of all points in the computation domain are determined by the aforementioned radial basis function series. To improve the efficiency, data reduction should be introduced into the interpolation process. Consequently, a multilevel subspace radial basis function interpolation method based on a “double-edged” greedy algorithm is presented to create an approximate interpolation for all moving boundary points. This method is computationally efficient, preserves orthogonality, and has no dependency on the type of flow solver. Typical deformation problems of a LANN wing, DLR-F6 wing–body–nacelle–pylon configuration and DLR-F11 high-lift configuration with hybrid-unstructured grid are selected as the test cases for demonstration of the current implementation. Results show that the present mesh deformation method has good efficiency and robustness for large and complex deformation problems.