Natural snowfall reveals large-scale flow structures in the wake of a 2.5-MW wind turbine

• DOI: 10.1038/ncomms5216
• Publication Date: 2014-06-24T15:02:14Z
• Authors: Jiarong Hong; Mostafa Toloui; Leonardo P. Chamorro; Michele Guala; Kevin Howard; Sean Riley; James Tucker; Fotis Sotiropoulos
• Keywords: 13. Climate action; 0211 other engineering and technologies; 0202 electrical engineering, electronic engineering, information engineering; 02 engineering and technology; 7. Clean energy

To improve power production and structural reliability of wind turbines, there is a pressing need to understand how turbines interact with the atmospheric boundary layer. However, experimental techniques capable of quantifying or even qualitatively visualizing the large-scale turbulent flow structures around full-scale turbines do not exist today. Here we use snowflakes from a winter snowstorm as flow tracers to obtain velocity fields downwind of a 2.5-MW wind turbine in a sampling area of ~36 × 36 m(2). The spatial and temporal resolutions of the measurements are sufficiently high to quantify the evolution of blade-generated coherent motions, such as the tip and trailing sheet vortices, identify their instability mechanisms and correlate them with turbine operation, control and performance. Our experiment provides an unprecedented in situ characterization of flow structures around utility-scale turbines, and yields significant insights into the Reynolds number similarity issues presented in wind energy applications.