Large-eddy simulation of wind turbines immersed in the wake of a cube-shaped building

Abstract

Motivated by the potential of wind power based electricity generation modules in urban environments, flow properties of wind turbines operating behind a building-like wall-attached cube are investigated through large-eddy simulation. Significant power losses with increased power fluctuations are observed for the first turbine downstream of the cube. Also, the power losses and fluctuations increase with decreasing distance to the cube. However, a faster recovery of the turbine wake is observed, due to not only enhanced turbulent transport but also due to convection associated with the secondary mean flow structure behind the cube. The transport of mass, momentum and energy fluxes shows that turbines at different distances receive mean kinetic energy from different layers of air motion upstream of the cube. Associated transport tubes exhibit deflection towards to the ground behind the first turbine due to the mean flow’s downwash, which can significantly reduce the sheltering effect of turbines at further downstream locations. Therefore, when a second turbine is placed behind the first turbine, the second turbine can produce more power than in the same setting without the cube. The total power output of two turbines behind a cube can be even larger than that without the cube, in certain cases.