Our History

 

Wind, together with human energy, has been the first energy source to be exploited for vessel traction over the sea.

As wind is a renewable and virtually endless energy source, it is foreseeable that, as long as the energy problem will continue to rise and become more and more urgent, wind could be destined to be the future of navigation.

Traditional sail traction evolution over the years allowed increasing performances, mainly thanks to new materials fabrication. However, traditional sailboats only exploit low altitude wind. Considering pure wind traction solutions, direct traction realised by airfoils has already been patented by BP in 1982 and adopted by SkySails as a possible solution. Such solutions are not particularly efficient, as vessels have no drift and the airfoil traction causes leeways, unless it is running downwind. But running downwind, besides being an inefficient point of sail for modern boats, is also inefficient for airfoil traction, as the vessel velocity has to be subtracted to the wind velocity. The SkySails solution has recently been adopted by Beluga Group, which equipped a carrier In 1924 a large two-rotor ship named Buchau was finished.

It was equipped with two propulsion cylinders put in rotation by individual motors. According to the sense of the rotation impressed to those cylinders, the wind incident on them allowed the ship to move towards the desired direction. It was discovered that the rotors did not give the slightest cause for concern in even the stormiest weather, and that the rotor ship could tack (sail into the wind) at 20-30 degrees, while the vessel with its original sail rig could not tack closer than 45 degrees to the wind. However, the rotor system was less efficient than conventional engines, and Flettner turned his attention to other projects and the rotors were dismantled.

Another direct wind traction system has been developed in the 80s by Cousteau, Malavard and Charrier, who designed and prototyped the first wind-propulsion cylinder based on the savonius principle, the Turbosail system, which equipped the experimental ship Alcyone (Patent n° US4630997).

The two 10,21 m high streamlined and rotating wingmasts are perforated with thousand of little holes to allow the air to enter and escape.

Fans moved by engines are placed at the top of the two Turbosails to accelerate the flow around the wingmasts and increase the lift, producing the driving force forward. The Turbosail is a Savonius turbine, whose maximum efficiency is 13%. The low performance of such solution, confirmed by the experimental results, can be easily measured considering that the whole intercepted wind front is around 50 m2. With a 10 m/s wind the power subtracted from the wind could be approximately 4 kW.

The wind energy harvested by the KITVES solution is not used for direct traction. Such solution allows to design a brand new concept of on board electric generator whose generation capabilities are essentially independent from the navigation conditions, allowing the vessel to navigate in any direction without compromising the system operativity.

The KSU (Kite Steering Unit) represents the basic element of the implementation of the KITVES Proposal.

The KSU can autonomously perform a cyclic two-phase wings array manoeuvre, simply acting on the two lines that connect the wings array to the fixed steering unit. The lines are connected to two alterno-motors by means of wrapping drums. In the traction phase, when the array of wings is lifted by the wind (properly driven in the most efficient way by the control), the lines unroll, the drums are put in rotation and the alterno-motors produce energy.

When the maximal length of the lines is reached, the control enters into the recovery phase, where the wing is driven to a region where the lines can be pulled by the motors until the minimal length is reached, spending a small fraction of the energy generated in the traction phase and a new traction phase is undertaken.

The following pictures show the trajectory of the wing as it results from some controlled flight simulations:

 
 

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20 Sep  Visit KITVES at Make. Innovate. Create

Come and find out about KITVES at the University of Sheffield's Make. Innovate. Create event on 18 October at the Knowledge Transfer Centre. The University of Sheffield ...Read more »

 

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Funding

KitVes is a collaborative project of the Seventh Framework Programme of the European Commission.


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