What is it about?
The oncoming turbulence is of particular importance with respect to the investigation of the turbulent flow fields over hilly terrain, which plays an essential role regarding the optimization of micro-siting of the wind farm and reasonable structural design of wind turbines. In this study, large-eddy simulations (LES) are performed to elucidate the effects of wind shear coefficients (WSCs) and upstream turbulence intensities (TIs) on the complex wind flow fields over the simplified 3-D hills. Systematical analysis of the wind turbulence properties related to the micro-siting and fatigue loads of wind turbines, including fractional speed-up ratio (SUR), terrain-induced TI, velocity spectrum and wind speed probability density function, is performed in a quantitative manner. Stronger non-Gaussianity is identified in the wake of gentle-sloped and moderate-sloped hills, which is weakened by increased WSC and enhanced TI. In addition, remarkable SURs are observed mostly at the summit of a steepsloped hill near the hill surface, and the fractional speed-up factor is found to increase significantly under higher WSC and larger TI. Furthermore, the influence of topography on the wind direction field is also examined, which shows little dependence on the WSCs and TIs.
Featured Image
Photo by Nate Watson on Unsplash
Why is it important?
The wind turbulence properties were examined systematically, which are crucial for both the calculation of dynamic response and fatigue load of wind turbines. In addition, the topography-driven speed-up effects and twisted wind direction effects were identified and discussed respectively.
Perspectives
In the current investigation, the influences of the WSCs and TIs on the turbulent flows over simplified hilly terrain have been examined by LES simulations. However, it should be noticed that the effects of approaching ABL flow with different WSCs and TIs on the flow fields over real complex terrain are still not clear, which require to be clarified in the following research. Furthermore, one of the primary purposes for this study is to facilitate the micro-siting of wind turbines in mountainous regions. Nevertheless, the coupling effects among the ABL conditions, topographies and wind turbines have not been considered simultaneously. The operation of wind turbines might affect the ABL conditions in turn, and the interference between wind turbines wake might increase the complexity of flow fields over hilly terrain. Hence, more systematic parametric studies of the turbine-hill system are needed in the near future.
Dr. Tong Zhou
The University of Tokyo
Read the Original
This page is a summary of: LES study of topographical effects of simplified 3D hills with different slopes on ABL flows considering terrain exposure conditions, Journal of Wind Engineering and Industrial Aerodynamics, March 2021, Elsevier,
DOI: 10.1016/j.jweia.2020.104513.
You can read the full text:
Contributors
The following have contributed to this page
