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DY: Fachverband Dynamik und Statistische Physik

DY 42: Turbulence

DY 42.10: Vortrag

Mittwoch, 14. März 2018, 12:30–12:45, BH-N 128

The decay of grid-generated wind tunnel turbulence — •Lisa Rademacher, Lars Kröger, Joachim Peinke, Gerd Gülker, and Michael Hölling — ForWind - Institute of Physics, University of Oldenburg, 26111 Oldenburg, Germany

Producing turbulent inflow conditions inside a wind tunnel by passive and active grids is an important measuring tool to simulate real wind conditions. Especially active grids have shown to be indispensable for controlling the inflow turbulence more precisely and reproducing unsteady processes. This is for instance important for examining wind turbines and how they perform in highly intermittent wind fields. Depending on the investigated problem different wind fields are required e.g. shear flows or unsteady flow events to simulate the turbulent atmospheric boundary layer or gusty wind loads. Since turbulence is characterised by its highly chaotic nature the reproducibility and controllability of the inflow conditions are of high importance. Also the invasive character of the grid itself should be as small or short-living as possible to prevent interfering of grid wake and measurement model. Ideally the grid wake should decay fast compared with the decay of the turbulent structures, which should last as long as possible - so the generated turbulence would exist without traces of the generating grid over the most parts of the measuring section. In this contribution the decay of the generated turbulence and the grid wake considering different flap movement patterns of a Makita-designed active grid are examined by the use of PIV.