14 research outputs found
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 Uâ. 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)
The development of packets of hairpin vortices in laminar channel flows in response to localized disturbances
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 ReΞ=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