Views: 12 Author: Site Editor Publish Time: 2019-11-27 Origin: Site
Although different from a HAWT, the core technology of a VAWT remains a wind mill structure with blades. After choosing an airfoil, it is necessary to calculate a concave orientation, angle, width, and quantity because each of these factors determines the performance of the VAWT.
So a first step is to choose a low-speed airfoil. A second step puts the concave orientation to outside, a third step chooses a small blade angle (8° works well) and a suitable blade width. The best blade quantity is five. And then the blade connection method is important. It’s best is to use socket structure for easy installation and reduced the drag forces. These factors determine the power generation performance of the VAWT.
A HAWT turbine must yaw − redirect itself into the wind − but the VAWT need not. So VAWTs muse use the “positive pitch attack angle regulation”. This feature uses centrifugal force to control the blade angle when the rotation speed exceeds the rated speed.
A good vertical axis wind mill has to remain stable when it is spinning it. If not, the turbine will “shake its head” when the rotor is turning. That will reduce the turbine’s life and cause other problems such as noise and mechanical wear. So the best solution is to use a coaxial structure for the wind mill and generator. The coaxial arrangement of wind mill and generator ensures a reliable seal, safety and stability, free of mechanical noise, a reasonable bearing for windmill, and a long useful life.
Damage may occur to wind turbines when the wind speed exceeds 25 m/s. So vertical axis wind turbine needs an automatic brake system. As a wind turbine starts to brake, it must overcome the rotational inertia and the driving force from the wind. So a good design calculates the torque in the rotor at survival wind speed and chooses a suitable disk brake for that amount of energy.