Enhancing vertical axis wind turbine by dynamic stall control using synthetic jets

Abstract

A novel application of modern active flow control on vertical axis wind turbine (VAWT) dynamic stall is explored in this paper. Operation of VAWT at low blade speed ratios offers numerous noise and safety advantages over higher blade speed ratios but suffer from dynamic stall that degrades their performance. Consequently, an experimental investigation was carried out on VAWT operating at low blade speed ratios that employed synthetic jets as a means of active flow control. Large angles of attack on VAWT rotor blades were simulated by sinusoidal oscillation of a thick NACA 0020 turbine blade about its quarter-chord. The pressure distribution and thrust hysteresis results showed synthetic jet actuation to be effective when dynamic stall effects were present, and clearly demonstrated that they could be utilised to improve low blade speed ratio VAWT performance and thus enhance turbine safety and noise. The findings from this study have significant practical implications for the design and development of safe and efficient wind turbines, both small- and large-scale, and further the cause of wind as a viable renewable energy source.