Effect of diffuser configuration on the flow field pattern inside wind concentrator

In this paper, the effect of the diverging part (diffuser) configuration on the flow field pattern inside wind concentrator is investigated by computational fluid dynamics (CFD) simulations. Diffusers with different diameter ratio, lengths and profiles are examined to estimate the optimum location of the turbine rotor inside wind concentrator and to attain minimum wake losses. The obtained results show that the optimum diverging diameter ratio (d₃/d₂) is 2, and diverging length to cylinder diameter ratio (l₃/d₂) is 1.33, respectively. The optimal diffuser shape is the convex that has a radius of curvature (R₂/d₂) of 2.293. The corresponding wind speed-up ratio (acceleration factor) K (= U_x/U_o) equals 2.33 at a corresponding axial distance measured from wind concentrator inlet, (x/d₂) equals 1.34 which is the optimum location of the wind turbine rotor.