Investigation of different transition models under disturbed inflow over a laminar wing

Kurzfassung

Efficiency of propeller-driven aircraft is strongly influenced by the interactions between wing and the propellers. The distributed propulsion concept could be effective in increasing the lift and delaying flow separation. However, the past studies focus on fully turbulent CFD solutions that do not take the local unsteady effects such as interactions between the propeller wake and wing-boundary layer into account. Considering a tractor propeller upstream of an NLF wing, the helical tip vortex and the trailing edge vortices shed by the propeller interact with the boundary layer periodically and boundary layer relaxation phenomenon [1] occurs. Relaxed boundary layers are more resilient to separation, and can delay transition onset. Relaxed boundary layers (also known as calmed region) have slightly elevated levels of shear stress than undisturbed laminar flow, but lower than that of turbulent flow.