Abstract
Wind turbines may suffer power loss after a long operation period due to degradation of the surface structure around the leading edge, by accumulation of contaminants and/or by erosion. For understanding the underlying physics, and validating the available prediction methods, the aerodynamics of smooth and artificially roughened airfoil profiles are investigated by different modelling procedures. A spectrum of turbulence models are applied encompassing RANS, URANS and DES. Two approaches are used to model the roughness. In one approach, the roughness is not geometrically resolved but its effect is modelled via the wall-functions of the turbulence models. In the alternative approach, the roughness structures are geometrically resolved, which necessitates a three-dimensional formulation, whereas the wallfunctions based approach may also be applied in two-dimensions. Computational results are compared with the experimental results of other authors, and the predictive capability of different modelling procedures are assessed.
Highlights
Wind energy is being increasingly used an in power generation from the renewable energy resources
We computationally investigate the leading edge roughness effects on airfoil aerodynamics applying different modelling approaches and compare the results with the measurements of Zhang et al [5]
Leading edge roughness was simulated by thin plastic strips with hemispherical roughness elements, which were placed in a region 5% chord length (c) from the leading edge in in-line or staggered arrangements, where the staggered configuration is considered in the present work
Summary
Wind energy is being increasingly used an in power generation from the renewable energy resources. Accumulation of contaminants and erosion can occur in a zone near the leading edge of the turbine, after a rather long operation period, which, causes a degradation of the performance. The SST turbulence model was applied by Zhang et al [16] to study the effect of roughness on a blunt trailing-edge airfoil in two-dimensions, assuming sawtooth like roughness shapes, resolved by the grid. We computationally investigate the leading edge roughness effects on airfoil aerodynamics applying different modelling approaches and compare the results with the measurements of Zhang et al [5]. An important distinguishing feature of the present work from the previous work is the application of three-dimensional surface roughness resolving approach, which was not investigated within this context before, along with roughness modelling via wall functions and assessing the performance of the latter by comparisons. A wide range of turbulence models are applied with and without transition modelling, and their performance is assessed
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