Regensburg 2016 – wissenschaftliches Programm
DY 57.9: Vortrag
Donnerstag, 10. März 2016, 17:30–17:45, H46
Intermittent Inflow Generation in CFD — •Sebastian Ehrich1, Bernhard Stoevesandt2, and Joachim Peinke1,2 — 1University of Oldenburg, Institute of Physics, ForWind, Germany — 2Fraunhofer IWES, Oldenburg, Germany
Complex and unsteady interactions between highly turbulent atmospheric inflow and the flow over wind energy converting systems (WECS) are of crucial importance with respect to the loads on the rotor blades. The disturbed inflow leads to a strong variation of the effective inflow angle over the entire rotor blade radius. Unsteady aerodynamic effects are the reason for phase shifts between excitation and resulting loads, but those effects have not been well described by models yet.
The content of this work is the implementation of a stochastic model based on continuous time random walks (CTRW) for wind fields in the CFD Opensource Code OpenFOAM as an inflow condition. The purpose of this project is the correct description and simulation of short scale fluctuations and extreme events described by longitudinal velocity increments. Those are interesting for load and fatigue calculations on wind turbines. Further, different simulation test cases are shown for proper analysis of turbulence characteristics of the model and the effect of filtering in LES compared to DNS simulations. Especially the decay of turbulence and the evolution of the increment probability density functions in space and time are considered.