Evaluation of the influence of the windbreak trees on the change of wind shear in weakly complex terrains

¹ Department of Power Engineering and Power Machines, Technical University of Sofia, 8 Kliment Ohridski blvd., 1000 Sofia, Bulgaria
² University of Ruse, Department of Thermotechnics, Hydraulics and Ecology 7017 Ruse, 8 Studentska Str., Bulgaria

^* Corresponding author: aterziev@tu-sofia.bg

Abstract

The turbulent nature of the wind above the earth’s surface depends on both the topology of the terrain and the presence of natural obstacles along the way such as low grasses and shrubs, as well as medium-tall trees. When the wind passes through the indicated obstacles, detachment is observed i.e. formation of large eddies, which are carried away by the main flow, after which they dissipate. The size of the vortices, as well as the period of dissipation, depends on the wind speed, as well as the type of obstacle. The presence of windbreak trees significantly changes the wind shear over the surface, and hence the energy potential of the wind in the vicinity of trees. In present work, the influence of the tree belt on the wind shear at the adopted prevailing wind direction is investigated. The degree of deformation of the speed profile after the obstacle in weakly complex terrain is shown. Relevant prescriptions for the location of wind turbines in the vicinity of windbreak trees are presented in view of minimum shading and maximum energy output.