Improvement of Wind Turbine Blade Performance by Means of Rod Vortex Generators

Abstract

Wind turbines are complex energy conversion fluid-flow machines which entail coupled aero-mechanical issues. From an aero-acoustical point of view, wind turbine blades present two main problems: first, a reduced aerodynamic performance due to flow separation, and second, the level of noise emissions. Flow separation appears on the blade as a result of high angles of attack causing a decrease in the aerodynamic efficiency. In this chapter, the application of rod vortex generators (RVGs) to control and decrease the flow separation-by the creation of streamwise vorticity on the blade-is presented. The NREL Phase VI wind turbine rotor and the S809 airfoil are used as reference cases. The validation of NREL Phase VI model rotor against experimental data is found to be satisfactory. A study into the effects of RVGs' chordwise location and spanwise distance is presented for selected cases and a range of inflow conditions. It is shown that the proposed RVGs lead to an improvement of the aerodynamic performance, and can be successfully applied by the wind energy industry. IntroductionThe wind energy sector has experienced rapid growth in the last few decades. The developments in the materials science, engineering and allied fields have ushered in turbines of increasing sizes; turbines with rotor diameters of up to 160 m (Vestas V164 8 MW) have been developed, and the current trend of increasing sizes is expected to continue in the future (Bak et al. 2012).The increasing sizes of wind turbines pose new challenges for engineers. One particular challenge is that large rotor dimensions result in non-uniform inflow conditions along the blade span-which leads to increased flow separation even after the application of traditional flow control approaches. As a consequence of

Performance investigation and energy production of a novel horizontal axis wind turbine with winglet

“…In the fluid cell zone, frame motion was selected with a rotational speed of 72 rpm. The computational flow domain created in Ansys Design modeler was shaped as a semi‐cylinder enclosing the single blade in line with the design followed by Martinez et al 63 and Aksenov et al 64 The computational domain with the domain size and boundary conditions imposed is shown in Figure 3. The semi‐cylindrical domain with periodic boundary conditions was chosen for the study as an alternative to the fully cylindrical domain to reduce mesh count and consequently computational effort and time.…”