Double shrouded horizontal axis wind turbine.
This research study deals with the design and optimization of a Shrouded Horizontal Axis Wind Turbine which is an emerging system in the field of renewable energy resources. The literature review shows that several authors have studied single shrouded horizontal axis wind turbines and many applications are in existence, but no development has been done in the field of double shrouded horizontal axis wind turbines. South Africa’s surging growth in electricity consumption requires development of this kind of wind turbine which can be implemented at both domestic and commercial levels. This research emphasis is on the development of a second shroud overlaying the existing shroud of a wind turbine. The research focuses on the development of a double shrouded horizontal axis wind turbine using a different type of NACA airfoil for the shroud and the blade in order to optimize the results. The objective of this research was to design and develop a shroud design with flanged ends which could operate a horizontal axis wind turbine at very low wind speeds. The effect of the double shroud on the wind speed is analyzed and optimized by simulation using different airfoil designs and profiles. The maximum wind speed increased 2.004 times at low wind speeds ranging from 2m/s to 7m/s and increased by 2.162 times for the high wind speeds ranging from 8m/s to 13m/s with the selection of an appropriate airfoil for the outer and inner shrouds. This shroud design is suitable for those areas where the wind speed is not very high due to urbanization and mega structures obstructing the wind flow hence reducing the wind speed. Also it is suitable for use in farm lands, rural areas, remote telecommunication stations etc. where it can stand alone in fulfilling energy requirements. In this study, Computational Fluid Analysis and optimization of the design were carried out using highly efficient CFD software, namely, Star CCm+. From the study we concluded that replacement of a single shroud with a double shroud provides a surge in energy efficiency of wind turbines of the same class.