We have developed a novel wind turbine that overcomes the solidity limitation of conventional designs, by opening the center of the rotor which allows to increase the number of blades without incurring loss of efficiency. According to our design, it is possible to increase solidity up to 0.25 (the recommended limit for three-bladed rotor is 0.1). Another important characteristic of our design is that the blades have a wing profile and twist, which is a function of the angle beta (between plane of rotation and chord at blade tip). The blades have a length equal to one/third of radius, which means that the inner opening amounts to one half of the complete circle. The set of blades are mounted between two rings that, besides serving as mechanical support, serve the aerodynamic function of winglets, to reduce loss of lift at the blade (both inner and outer) tips.
One of our prototypes was tested by the laboratory of Fluid Dynamics of the Faculty of Aeronautical Engineering (La Pl.ata National University). The results confirmed all our expectations as regards power (1500 W @11 m/s wind speed),and torque (85 Nm at the same wind speed).
Thus our design achieves a number of advantages with respect to the conventional three bladed design:
a) allows use of light materials and construction (such as used for ultralight wings
b) a more resistant structure characterized by the absence of elements subjected to high torsion moments
c) higher Cp (power coefficient) over a wider range of specific wind speeds (lambda)
Another important advantage is the design scalability.