Darrieus wind turbine

The Darrieus wind turbine is a special kind of vertical-axis wind turbine used to make electricity from the power of the wind energy. Instead of having big blades that spin around a horizontal axis like many turbines, a Darrieus turbine has curved blades arranged in a vertical shape. These curved blades, called aerofoil blades, spin around a central shaft.

Because of their unique curved shape, these blades are mostly pulled by the wind rather than pushed, which helps them spin smoothly at high speeds. This design was invented by Georges Jean Marie Darrieus, a clever French aeronautical engineer, who applied for a patent for this idea on October 1, 1926.

Even though Darrieus turbines are interesting and useful for producing clean energy, they can be tricky to protect from very strong winds and sometimes need help to start spinning on their own.

Method of operation

The Darrieus wind turbine has symmetrical blades arranged so they work no matter which way the wind blows. Unlike regular wind turbines, it does not need to turn to face the wind. When it spins, the blades move through the air in a circle. This motion creates a force that helps the turbine keep rotating.

One challenge with this design is that the force changes as the blades spin, causing a pulsing power output. The turbine also needs to be already spinning to generate power, so it is not self-starting. To handle strong forces, the blades are often curved into an "egg-beater" shape, which helps them stay strong without heavy supports.

Giromills

Darrieus's 1927 patent included many ways to arrange vertical airfoils. One popular type is the H-rotor, also known as the Giromill or H-bar design. Instead of curved "egg beater" blades, this design uses straight vertical blades connected to the central tower with horizontal supports. This design is used by a company in Shanghai called MUCE.

Cycloturbines

A Cycloturbine is a special kind of wind turbine where each blade can spin around its own vertical axis. This lets the blades stay at the best angle to catch the wind, which helps the turbine produce steady power. It can also start spinning on its own by angling one blade to catch the wind like a sail.

Auto-Cycloturbines take this idea further. Their blades automatically adjust their angle without any sensors or computers, using the wind's force to find the right position. This makes the turbine simpler but still needs careful design to work well.

Helical blades

The blades of a Darrieus turbine can be shaped into a spiral, like a helix, to help the turbine turn smoothly. This design was first created by Ulrich Stampa in 1979 and later suggested by A. Gorlov in 1995. This special shape makes sure the turbine spins evenly, which helps it work better without shaking too much.

This design is used by several companies such as Turby, Urban Green Energy, Enessere, Aerotecture, and Quiet Revolution for their wind turbines.

Active lift turbine

The relative speed of the wind creates a force on the blade of a Darrieus turbine. This force can be split into two parts: one along the direction of the turbine’s rotation (axial force) and one perpendicular to it (normal force). In a Darrieus turbine, the axial force helps turn the turbine, while the normal force puts stress on the arm—sometimes pushing it and sometimes pulling it—during each half turn.

To make use of this stress, a crank rod system can be added. This system changes the back-and-forth stress into extra energy that the turbine can capture, making it more efficient.