Experimental investigation of the effect of the Reynolds number on the performance of a micro-scale and low tip-speed ratio wind turbine

Abstract

Micro-scale wind turbines are of great interest to supply rechargeable batteries of autonomous sensors in the field of the Internet Of Things (IOT). However, they face the issue of lower dimensionless performance than large-scale wind turbines. Due to their small size and low operating wind speed, these runners operate mainly in low Reynolds number flow conditions at which the aerodynamic properties of the blades are not well-known. Even though promising results are reported on the Reynolds number effects on isolated and non rotating blades, their applicability to design efficient small rotating energy harvesters is questionable. This paper reports on the influence of the Reynolds number on the performance of high-solidity and low tip-speed ratio micro-scale wind turbines. Wind turbine’s power and torque coefficient vs. tip-speed ratio curves are measured in wind tunnel for a wide range of Reynolds number by changing either the turbine’s diameter or the free-stream wind velocity. This quantitative analysis will contribute to design more efficient wind energy harvesters.