Turby wind turbine

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Turby prototype - TU Delft

The Turby is a brand of vertical-axis Darrieus wind turbine. The three vertical aerofoil blades have a helical twist of 60 degrees, similar to Gorlov's water turbines .

The turbine consists of three vertical symmetrical airfoil blades, each having a helical twist. The helical feature spreads the torque evenly over the entire revolution, thus preventing the destructive pulsations of the straight-bladed giromill (Darrieus turbine). The wind pushes each blade around on both the windward and leeward sides of the turbine. As with a Darrieus turbine, theoretically, there is no torque on a stationary turbine, due to symmetry of the turbine and of the blades. Starting is achieved by operating the generator as a motor. Torque is caused by a change in the apparent wind direction relative to the moving blades.

Another advantage of the helical twist is that the blades generate torque well from upward-slanting airflow.^{[citation needed]} This is negligible in open country, but tall buildings and cliff faces generate a bow wave which directs airflow up and over them. Turbines mounted on high building rooftops or clifftops are exposed to significantly slanting flow, and the Turby can extract more useful energy from it than a propeller-type turbine can^{[citation needed]} because HAWT types need time to adjust their yaw to face the wind direction.

The turbine measures 2.0m (6'7") in diameter by 2.9m (9'6") high (including generator), and weighs 136kg (300lb). It is specified to generate power in winds of between 4m/s (9mph, 7.8kts) and 14m/s (31mph, 27.2kts), and can survive winds of 55m/s (123mph, 107kts). The rated power at 14m/s is 2.5kW (3.35hp). The AC output from the synchronous generator is rectified to DC, then inverted to AC at 230V 50Hz.

Core International developed the turbine in the Netherlands with research input from the Delft University of Technology.