A new configuration of vertical axis wind turbine: an overview on efficiency and dynamic behaviour

Preliminary results obtained for a new configuration “lift based” vertical axis wind turbine are shown. The turbine rotor is a cross flow fan type characterized by an high solidity and having the blades made of high curvature aerodynamic profiles which allow it to start at very low wind speed. A reduced scale model ( Rotor diameter = 250mm, rotor height = 210mm , 24 blades ) has been tested at the Department of Aerospace Engineering of Pisa showing an efficiency of about 18%. During the test a complete analysis of its aeroelastic response has been carried out through the use of four strain gauges properly placed. Good correlation with FSI and rotor dynamic analyses have been obtained. Furthermore steady and unsteady CFD simulations have been carried out using Ansys Fluent® Rel.14 and STAR-CCM+® Rel. 6.04 with the Moving Reference Frame and Moving Mesh techniques. CFD analyses confirm the results and give important information about its behaviour and the aerodynamic loads to which it is subjected. Noticeable scale effects have been found numerically, so, the efficiency of a full scale lift based vertical axis optimized wind turbine is expected to be comparable with lift based horizontal axis wind turbine, i.e. around 30%. A full scale model of diameter = 1m and height = 1m is currently under construction and will be tested in field in order to validate the numerical results. An efficiency of about 22% is expected. Since its optimal angular velocity decreases as the scale increases, vibrational phenomena for the full scale model are supposed to be almost null. Due to its simplicity and its principle of operation, hydrodynamics applications are also quite promising.