Investigation of Different Transition Models under Disturbed Inflow over an Airfoil

Kurzfassung

Relaxed boundary layers, also known as the calmed regions, form after the passage of turbulent spots. Calmed regions can intermittently delay transition and extend laminar flow. The forming of such a relaxed boundary layer is investigated on a wing exposed to unsteady, turbulent inflow caused by a moving rod using numerical simulation. The numerical set-up is a 2-D adaptation of a rotating rod-wing configuration experiment, whose data were used for validation. The relaxed boundary layers are simulated with the DLR-TAU code using URANS equations alongside 1- and 2-equation transition models. Calmed region, which forms after the passage of the turbulent rod wake, temporarily delays the transition and extends the laminar flow on the upper surface of the airfoil from 45% up to 75%. The velocity profiles obtained in the numerical simulations agree very well with the experimental boundary layer profiles.