What is a Darrieus turbine?
A Darrieus turbine or Darrieus machine is more or less similar to an H-rotor in terms of having a vertical axis and working based on lift forces on the blades.
Th e difference is in the way the blades are attached to the shaft . A Darrieus turbine has the shape of an egg beater. Instead of the blades being attached to the shaft in the center, they are continued from both up and down and are curved.
Th e blades are attached to the shaft at both ends. Figure below shows a picture of a Darrieus machine. Th e curvature of the blades allows the vertical shaft to be supported by a number of guy wires. In this sense, the main tower supporting the turbine shaft does not need to be as solid and strong as it must be in an H-rotor.
A disadvantage of a Darrieus machine is that it does not have a good starting torque. Th is means that at low wind speeds it cannot easily start to rotate. Aft er it starts rotating, however, it has a good torque and can continue to generate electricity.
Despite the two main advantages of vertical-axis turbines (not being sensitive to wind direction change and most of the components being accessed from the ground), not many Darrieus machines have been built in the past, and none is made today. From practicality, preference is given to propeller turbines.
Darrieus turbine
A vertical-axis wind turbine that looks like an eggbeater.
No comments:
Post a Comment