Effects of Mie Vanes and Tip Injection on the Performance and Wake Characteristics of a HAWT

Abstract

This paper presents the results of an experimental study that focuses on the tip leakage/vortex control of a model horizontal axis wind turbine rotor. The effects of Mie vanes and tip injection on the performance and wake characteristics of a model horizontal axis wind turbine rotor are investigated through experiments that are conducted by placing a specially designed three-bladed horizontal axis wind turbine rotor at the exit of an open-jet wind tunnel facility. The rotor blades are non-linearly twisted and tapered with NREL S826 airfoil profile all along the span. The measurements include power and thrust coefficient variations with Tip Speed Ratio (TSR) as well as wake flow field measurements at different axial locations downstream of the turbine rotor. Results show that both techniques significantly influence the power and thrust coefficient variations especially near the TSR ranges where CP is maximum. Mie-vanes reduce the strength of the tip vortex and hence reduce the associated turbulence intensity levels within the tip vortex dominated region inside the wake. Tip injection on the other hand introduce higher turbulence levels because of the strong turbulent jet injected from the blade tips. It’s expected that this higher turbulence levels could contribute to the faster diffusion of the tip vortices within the wake downstream of the turbine rotor.