Wind shear effect on aerodynamic performance and energy production of horizontal axis wind turbines with developing blade element momentum theory

Nowadays, the optimal use of energy is one of the most important things in energy engineering. Disadvantages of fossil fuels make renewable and cleaner energy sources more widely used. Wind energy is a type of clean energies that will help humanity transition to a sustainable future. The power of wind turbine depends on many parameters such as wind profile and blade geometry. In most studies, wind speed is generally considered to be constant and uniform along the rotor blades. But in fact the nature of wind has irregularities in space and time. Moreover, wind shear leads to non-uniformity in wind vertical profile. Having a good understanding of these kinds of spatial and transient irregularities and also their influence on wind turbine performance reduce uncertainty in design process. In the present study the blade has been designed by blade element momentum (BEM) theory and aerodynamic coefficients have been calculated along the blade length. The effects of wind shear have been studied on the designed blade. Power law has been used to model wind shear. By merging this function with BEM theory, its effect can be calculated along the blade length. Results show that wind shear has little impact on aerodynamic coefficients near the root region. Most of changes occur at 0.2 to 0.8 of the blade length. Furthermore, existence of shear in wind profile regarding the turbine designed for uniform inflow, reduces the kinetic energy flux, ability to extract the available potential and power generation.