Blade design considerations of small wind turbines: From classical to emerging bio-inspired profiles/shapes

Abstract

The utility of small wind turbines (SWTs) covering horizontal and vertical-axis types as off-grid, standalone, and decentralized energy supplement systems has gained market attention. Such turbines operate primarily at low Reynolds number (Re) and low tip speed ratio (λ) conditions. Under such circumstances, the design, development, and testing of SWTs have become a tedious task, mainly due to the lack of precise aerodynamic knowledge of SWTs. This article reviews the fundamental aspects of SWTs, including airfoil selection criteria, blade design, and aerodynamic improvement through passive flow control and augmentation techniques. It also reports several classes of potential airfoils that can be employed in the design of SWTs. The airfoils considered operate mainly in the range of Re = 0.3 × 105–3 × 105 and λ = 0.5–6. Aside from the classical approach, this article showcases the prospects of several bioinspired profiles/shapes that are meant for SWTs operating at low Re and λ conditions. Toward the end, various design constraints and applicability of SWTs are summarized.