Regensburg 2010 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 24: Turbulence and wind energy

DY 24.2: Vortrag

Donnerstag, 25. März 2010, 10:15–10:30, H47

Lift measurements in turbulent flow — •Jörge Schneemann, Pascal Knebel, and Joachim Peinke — ForWind, University of Oldenburg, Institute of Physics, Germany

We present lift measurements in a wind tunnel on a FX 79-W-151A airfoil using simultaneously two different methods in laminar and turbulent flow. The first method measures the pressure distributions on the wind tunnel walls to calculate the lift coefficient. This method was shown to work in laminar flow before. The second method measures the lift forces directly on the mounting of the airfoil with a strain gauge based system. Simultaneous measurement gives the opportunity to compare the results of both methods. Hereby, the wall pressure method was proven to obtain good time averaged results in turbulent flow.

Lift was measured in several turbulent inflows with different turbulence intensities Ti generated by grids. Lift forces in the stall range of the foil increased with Ti. One of the grids had a fractal geometry (fractal grid). The turbulence generated by this grid differs from turbulence generated by ’classic grids’ in the distribution of the velocity increments. This leads to a different behaviour of the airfoil: Lift fluctuations measured in the stall range of the foil were much higher in the wake of the fractal grid than those in the wake of a classical grid with higher Ti. This suggests a nonlinear behaviour of the airfoil for which research is ongoing.