Effects of Different Friction Control Techniques on Turbulence Developing Around Wings

Developing efficient flow control techniques remain a challenging task due to the complexity of turbulent flows in industrial applications, a relevant example of which are turbulent boundary layers (TBL) subjected to pressure gradients. In the present study, we employ high-fidelity numerical simulations to assess the impact of different control strategies on the flow around a NACA4412 airfoil at a Reynolds number Rec=200,000 based on the chord length c and the inflow velocity U∞. The choice of this specific study case is motivated by the relatively weak dependence of the pressure distribution around the airfoil on the Reynolds number [6], which allows distinguishing the effects of increasing Reynolds number and those of the non-uniform adverse pressure gradient (APG)

Investigation of 3D Coherent Structures in Turbulent Boundary Layers at High Reynolds Numbers using MultiPulse-STB

Large wall shear stress events in turbulent boundary layers (TBLs) produce significant drag and are determined by the dynamics of coherent structures. A fundamental research experiment was performed in the Cross Wind Test Facility Göttingen (SWG) at German Aerospace Center (DLR) in Göttingen, in order to get a deeper understanding in these structures at high Reynolds numbers. For high-resolution studies in the near-wall and logarithmic region, the Multi-Pulse Shake-The-Box (MP-STB) measurement technique for 3D Lagrangian Particle Tracking was applied to a zero pressure gradient flat plate TBL at a Reynolds number of Reθ=10,000. Three dimensional observations of coherent structures even in the near-wall region down to y+=2.5 were done by using quadrant analysis, 2-point correlations and FlowFit visualizations