Direct TS-Wave Simulation Behind the Generic Step of a Laminar Wing-Profile in the DNW-NWB Wind-Tunnel

Kurzfassung

Direct numerical simulations of Tollmien-Schlichting waves behind generic obstacles on a generic laminar~airfoil, designed as a reference-configuration for experimental investigations, will be shown in the following computational studies. The character of the dominating transition mechanism by Tollmien-Schlichting (TS) waves allows 2D simulations, using a well-validated high-order numerical approach, which will be suited for detailed simulations of transitional modes in the region of interest. All simulations of transitional modes were carried out on the original airfoil-geometry by using an entirely meshed step-area. The middle part of the airfoil~nose in the open test-section of the DNW-NWB contains an adjustable inset to allow settings of different forward and backward facing steps which was comparable with high-resolution CFD-results. Efficient time-accurate simulations of the TS-mode growth were carried out on extracted CFD-grids of the critical region. Unsteady perturbations were added at inflow, which resemble TS-modes in the step-region. Determining growth rates of these modes allow comparison with Linear Stability Theory (LST) and the prediction of the laminar-turbulent transition.