3-D blade resolved CFD performance analysis of ducted wind turbines

Ducted wind turbines are very promising wind energy concentrator-systems for small-scale applications exhibiting an appreciable power density increase compared with their open rotor competitors. The aim of this work is to build up a robust and automated methodology for the 3D blade-resolved performance analysis of these devices in view of their CFD-aided optimal design. The reliability of this procedure, based on an in-house Python module for the generation of the structured multi-block 3D mesh, is verified by comparing the obtained numerical results with available experimental data. The developed methodology is employed to spotlight the differences in terms of extracted power between open and ducted rotors and to investigate some typically-disregarded aspects playing a key role in the design and analysis of ducted wind turbines. Specifically, it is shown that the shrouding of an existing open rotor leads to a sub-optimal turbine operating condition as well as to a significantly change in the local features of the tip vortex and associated losses