This chapter focuses on airfoils for wind turbine blades and their characteristics. The use of panel codes such as XFOIL and RFOIL and CFD codes for the prediction of airfoil characteristics is briefly described. This chapter then discusses the requirements for wind turbine blade airfoils and the effect of leading edge roughness and Reynolds number. After a description of how airfoils can be tested, this chapter discusses methods to represent airfoil characteristics at high angles of attack. A number of methods for correcting characteristics for the effect of three-dimensional flow on the blade are presented. This chapter then discusses ways to establish a data set for blade design and concludes with a view on future research in the field of wind turbine blade airfoils.

An experimental aero-acoustic characterisation of the NACA 63 ₃-018 airfoil is presented in this study, featuring trailing-edge noise emissions with and without serrations. Measurements have been carried out for a chord-based Reynolds number range between 0.18 × 10 ⁶ and 4.8 × 10 ⁶ . Two airfoil models with different chord lengths have been tested in five different wind tunnels. The goal is to compare the measurements in different facilities, quantify the uncertainties, and establish a validation database that can serve as a benchmark for computational studies. The tests have been performed with clean and forced-transition boundary layers for a variety of angles of attack. The effect on the spectral slope and peak levels is evaluated. Scaling laws have been applied to compare different test conditions. The quality and nature of the collapse, as well as the applicability limits of the scaling, are examined. Different serration geometries have been tested at different flap angles. The noise reduction dependence on the aerodynamic loading is discussed. This work is based on an initiative of Task 39 "Quiet Wind Turbine Technology" of the Technology Collaboration Programme (TCP) of the International Energy Agency (IEA).