Experimental and computational study of the performance of a new shroud design for an axial wind turbine

Abstract

A new shroud design for horizontal wind turbine was shaped by revolving an airfoil E423 (high lift force) about an axis of symmetry. A lift force is generated by the flow through the shroud, and the effect of this lift is to increase the mass flow rate through the rotor plane. This study found that the efficiency of the augmentation velocity factor is substantially dependent on the shape and geometry of the shroud, particularly the length, angle of attack of airfoil E423, and area ratio. Results obtained from numerical simulation showed that the augmentation velocity factor increases linearly with increasing area ratio and the shroud length. The experimental investigations on an empty micro-shroud, using a low airspeed wind tunnel, showed good agreement with computational fluid dynamics (CFD) of velocity distribution at the throat area and augmentation velocity factor, with error 1.06%. In addition, six different shrouds were modeled with different configurations and analyzed computationally with the aim to understand the influence of the length, angle of attack, and area ratio on power augmentation, and the effects of external loads. This study also investigated experimentally the extracted power on a micro-shroud of an optimized shroud design with an area ratio of 2. Tests confirmed that placing the micro-wind turbine in the throat area of the shroud could strongly improve its performance by factor of 1.7-2.3 times as compared to a wind turbine without shroud. Further, it is shown theoretically that the output power boosts with increasing the area ratio of the shroud, and inlet air velocity. Finally, in order to design the sustainable shrouded wind turbine that would survive an extreme wind gust that is many times greater than normal wind speeds, the drag force effect was analyzed computationally on empty 3-Dimensional shroud models using ANSYS-FLUENT15.