Shrouded in near-silence

A new design of wind turbine could provide significantly better power output than existing mills, while overcoming some of their drawbacks, such as noise and high maintenance requirements. Victor Jovanovic, inventor of the Stormblade turbine and founder of a UK company with the same name, claimed his design incorporates all the virtues of a partially static turbine design with a more aerodynamic solution to the problem of drag. One of the biggest problems with current turbines is that once the wind gets above 60mph, they have to be shut down, because at higher speeds, a gyroscopic effect is created in the driveshaft. Gyroscopic precession tries to twist the turbine, placing stress on the blade and mechanism, causing them to break. Conversely, if the wind speed drops below about 15mph, the blades’ rotation is not fast enough to generate electricity. An alternative is to use a design where the blades are surrounded by a shroud that channels the airflow onto the turbine — a little like a scoop. Prototypes have shown that the efficiency of power generation is increased significantly — up to three times higher than a traditional three-bladed mill. However, the shroud facing into the wind, combined with the high speed of rotation of the air current, tends to create a parachute effect, and extreme forces are exerted on the tower. This means that the tower has to sit on scaffolding, rather than a single pole, and consequently would be both expensive to build and require a large amount of land. The Stormblade turbine aims to overcome these problems. ’It uses some of the principles of the shrouded system, channelling airflow into the turbine and on to the blades,’ Jovanovic said. ’It also overcomes the problem of precession, allowing the turbine to operate at much higher speeds.’ The problems experienced by existing shrouded systems have been resolved by addressing the aerodynamics. Essentially, the shroud cowling is shaped like a jet engine.