Building Effects on a Horizontal-Axis Micro Wind Turbine: Experimental and Fluid-Dynamic Analysis

In this work, the efficiency of a 1 kWp horizontal-axis wind turbine installed on the roof of the Engineering building at the University of Salento has been evaluated, by means of CFD and experimental data. Particularly the influence of the building on the micro wind turbine performance has been studied and the numerical results (wind velocity fields and turbulence intensity above the building) have been compared with the experimental data collected over a period of time of three years. The results have shown that horizontal axis wind turbines suffer from wake effect due to buildings, therefore best sites in urban area have to be identified by a careful fluid dynamic analysis aimed at evaluating all causes that can reduce significantly the performance of the generator: in fact building should allow to exploit increased wind intensity, but often this advantage is voided by turbulence phenomena, as in the case under investigation where the measured aerogenerator efficiency is lower than the nominal performance curve. Then, the best site can be found by crossing the contours of wind velocity with the turbulence intensity fields: in this way it is possible to localize an area (best location) where the aerogenerator can gives maximum performance.