Numerical Investigation of a Finite Wing Model in the Side Wind Test Facility Göttingen

Abstract

In this thesis work, numerical simulations were performed using the Reynolds-Averaged Navier-Stokes (RANS) solver DLR-TAU code, in order to investigate the static flow around the finite wing in farfield and in the wind tunnel. Several experimental and numerical investigations have been carried out at DLR in the past on two-dimensional airfoils. In order to understand the three-dimensional effects and the influence of a finite wing on the stall phenomenon, a finite wing model was experimentally investigated in the Side Wind Test Facility Göttingen. As a first step in this project, two-dimensional computations were carried out with the DSA- 9A airfoil and the flow was analysed. Then, three-dimensional simulations were performed with the finite wing model in farfield boundary conditions. In order to investigate the three-dimensional effects, the three-dimensional farfield simulation results of the finite wing were compared with the two-dimensional simulation results of the DSA-9A airfoil. Furthermore, validation of the farfield simulation results have been done, by comparing them with the available experimental results. Finally, three-dimensional simulations of the finite wing in the wind tunnel were carried out. For examining the influence of the wind tunnel walls on the flow around the finite wing, the obtained results were compared with the results of the farfield simulation. Subsequently, the three-dimensional numerical results of the finite wing in the wind tunnel were also compared with the experimental data to determine the differences between the results. The static stall was found to take place at α = 15° for the DSA-9A airfoil. Comparison of the three-dimensional farfield simulation results of the finite wing with the two-dimensional simulation results of the DSA-9A airfoil showed higher lift being created in the 3D simulation than in the 2D simulation, due to the positive linear twist of the finite wing. However, the finite wing stalled earlier than the 2D airfoil. By comparing the farfield simulation results with the wind tunnel experimental results at three chordwise cut planes, it was revealed that, the onset of static stall was delayed by 1° in the farfield simulation, when compared to the experiment. In the wind tunnel simulation, the streamwise velocity was found to be higher, leading to a higher lift, in comparison with the farfield simulation and the wind tunnel experiment. Nevertheless, the static stall of the finite wing occurred at the same angle of attack in the wind tunnel experiment and in the wind tunnel simulation.