Chapter 2 A Review of Wind Turbine Yaw Aerodynamics Daniel Micallef and Tonio Sant Additional information is available at the end of the chapter http://dx.doi.org/10.5772/63445 Abstract The fundamental physics of H“WT aerodynamics in yaw is reviewed with reference to some of the latest scientific research covering both measurements and numerical modelling. The purpose of this chapter is to enable a concise overview of this important subject in rotor aerodynamics. This will provide the student, researcher or industry professional a quick reference. Detailed references are included for those who need to delve deeper into the subject. The chapter is also restricted to the aerodynamics of single rotors and their wake characteristics. Far wake and wind turbine to turbine effects experienced in wind farms are excluded from this review. Finally, a future outlook is provided in order to inspire further research in yawed aerodynamics. Keywords: horizontal axis wind turbine, yaw, unsteady aerodynamics, wakes, rotors ŗ. Introduction: The relevance of wind turbine yaw aerodynamics ŗ.ŗ. Wind turbine yaw fundamentals “ wind turbine converts the kinetic energy from the wind to electrical energy. The power which can be extracted is proportional to the cube of the wind speed. There is, however, a theoretical limit to the power which can be extracted from the turbine. This is known as the ”etz limit. This limit was derived by ”etz [ŗ] to correspond to śş% of the maximum available power which can be extracted by the turbine. The efficiency of a wind turbine is called the power coefficient and is defined by the followingǱ © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.