• Dr. Luciano Castillo
  • Texas Tech University
  • 113 McBryde Hall
  • 4:00 p.m.
  • Faculty Host: Dr. William Devenport

Although wind turbines have been well studied from a blade aerodynamics perspective, the interactions among these massive structures and the atmospheric turbulent boundary layer (ATBL) are still not understood in detail. It is important to understand such interactions in order to maximize the energy that can be extracted from the available wind resource. Past investigations have determined that wind turbines that operate within an array can display a significant power generation loss, when compared to a freestanding wind turbine. Thus, their ability to extract kinetic energy from the flow decreases due to complex interactions among them, the terrain topography and the atmospheric boundary layer. 

In order to improve the understanding of the vertical transport of momentum and kinetic energy across a boundary layer flow with wind turbines, wind-tunnel experiments were performed to include: a single wind turbine blade, a single wind turbine and a scaled down wind array. The boundary layer flow includes a 3 X 3 array of model wind turbines. Particle-image-velocity measurements in a volume surrounding a target wind turbine are used to compute mean velocity and turbulence properties averaged on horizontal planes. The impact of vertical transport of kinetic energy due to turbulence and mean flow correlations is quantified. It is found that the fluxes of kinetic energy associated with the Reynolds shear stresses are of the same order of magnitude as the power extracted by the wind turbines, highlighting the importance of vertical transport of turbulence in the boundary layer and thus in wind farms.  Moreover, the streamtube is visualized in a single wind turbine in order to gain insight into the flow and to test the axisymmetric assumption used for the calculation of the induction factor. Results show that the streamtube is indeed close to axisymmetric, but exhibits some slight distortions due to strong tower effects and shear from the wall.