Wind Turbine Principle

rotation. It was also thought it was only possible to create lift by the blades if they were traveling into the wind direction of the wind flow and the drag on the opposite blade traveling down wind was not a desired effect. But symmetric airfoil is not the best shape to provide a lift. There have been number of attempts in using hinged blades which are attached to the end of the cross arm, which allows the airfoil section of the blade to maintain its optimal angle of attack. Darrieus vertical axis turbines principle of operation. Because of rotation, the wind speed and the airspeed form a positive angle of attack of the lift force. When the wind flows over the high lift and low drag, it gives the turbine the initial power that is needed to

Since the Darrieus wind turbine is not self-starting, meaning it has a low-starting torque. A torque is an action that causes objects to rotate and is required. When a torque does work on a rotating rigid body, or wind turbines, the kinetic energy changes by an amount equal to the work done. The Darrieus produces a low-starting torque and produce negative torque if the TSR is low. As a result, it lowered up to a speed where the aerodynamic torque is sufficient to accelerate the rotor to normal operational speed But the turbine is not dependent on wind direction and has no yaw system and therefore no control system to point the turbine into the wind, it compensates for the lack of self-starting ability. But the capacity for self-starting can be achieved through number of strategies: increased solidity, using odd number of blades, use some sort of blade pitch mechanism, and using blades that are skewed in order for the blade azimuth angel to be a function of axial distance along the rotor . The Darrieus wind turbine has several subsystems, which

This type lift based design is considered one of the most attractive solutions because it is simple and easy to manufacture. The Giromill can be controlled by stall or pitch control. The drag/stall effect caused by the traditional Darrieus rotor blades limits the speed of the wind flow of the opposing blade. The Giromill was then designed to be self-controlling in all wind speeds where it would reach its optimal rotational speed, shortly after the cut-in-wind speed. The Giromill is ideal in large-scale electricity production because it has lower and more predictable stress loading on the blades than other VAWTs. But this large-scale production of electricity of the Giromill has not been fully researched because of earlier design failures and partly because they have slightly lower blade efficiency. There are some parameters that affect the performance of those types of turbines. The most important once being