GwindPP

Wind Turbine Blade Aerodynamics:  Horizontal  Axis Turbines    A rotating turbine blade experiences oncoming wind differently, which is called relative wind. A section of the turbine blade receives a wind velocity differently due to its rotation.   The interaction between oncoming wind and a blade generates lift and drag forces.   Drag force is in the same direction as the relative wind, and it holds the blade back. The lift force is perpendicular to the relative wind (Figure 1).   A maximum lift and minimum drag forces are needed to achieve a higher power coefficient.   Modern Wind turbine blades have an airfoil shape to get an optimal angle of attack and greater lift force (Figure 2).    An angle of attack above certain degrees increases the drag force and causes a stall (Figure 3).   Wind Turbine Blade

Wind Power Extraction by Wind Turbines There is a limit, only a partial extraction of power available in the wind is possible. The amount of extracted wind power in percentages is termed the Power Coefficient (Cp). For example, 25% Cp indicates that only 25% out of 100% available wind power is extracted.    The limit for power extraction from wind is 59.3%, which is Betz's law. A wind turbine extracts wind power by slowing down incoming wind velocity through the rotor blades and letting pass through. The maximum power is extracted when the incoming wind velocity is reduced by one-third at the rotor.   The actual Power Coefficient (Cp) of a wind turbine is below 59.3% due to aerodynamic, generator, and cable losses.   Modern wind turbines operate at a certain Tip Speed Ratio (TSR) to optimize the power output. TSR is the ratio between the velocity of the tip of the blade and the incoming wind speed. The rotor of a wind turbine rotates at a cer...

Technical Specifications of Wind Turbines Some Technical Specifications of Wind Turbines:   Rated power is the maximum power that can be safely produced at the given range of wind speed by a wind turbine. For example, the rated power of 4000 kW at the range of 13-23 m/s wind speed.   The number of blades - horizontal axis three-bladed wind turbines are the most common.   Horizontal-axis rotors are upwind or downwind. For example, an upwind rotor with a clockwise rotation.   Wind turbine generators are synchronous or asynchronous. Synchronous generators are best suited with direct drive gearless systems and asynchronous generators with gears.   The Yaw system is a mechanism that allows turning a rotor in the upwind direction.   The power curve of a wind turbine is a curve that demonstrates power production and power coefficients at a specific range of wind speed.   Inside of the Nacelle of a Wind Turbine ...