Abstract
The negative implications of indiscriminate usage of fossil fuels lead to many problems such as high carbon dioxide emissions that pollute the atmosphere and change the global climate. Wind energy is promising clean energy and it is ample supply and a nonpolluting power generation method. Wind turbines are renewable energy devices but are fraught with challenges such as low wind speeds and high turbulence intensity. In the present work a comprehensive study is introduced to enhance the aerodynamic performance of a Darrieus turbine by enclosure it in a flanged diffuser. The conventional blade shapes of NACA 0015 and DU 06-W-200 profiles as well as non-conventional blade shapes such as J-shape design are investigated. The geometric modifications and different parametric studies conducted are also described in details with the relevant discussion of results obtained. This all followed by a numerical prediction scheme for noise is accomplished using the Ffowcs Williams & Hawkings process. The results revealed that the modification on the classical profile of the aerofoil has an important role in the enhancement of the power generated at a certain diffuser location. The optimum configurations improved the power coefficient by a factor of 2.24 in the case of NACA0015 and by factor 1.866 in case of DU06-W-200 aerofoil compared with conventional three-bladed Darrieus turbine. Furthermore, the J-shaped profile is promising from performance and aeroacoustics point of view in this low-moderate tip speed ratio range but is totally collapsed in front of the low solidity. (C) 2019 Elsevier Ltd. All rights reserved.