| Wind energy is considered to be a promising renewable energy source, particularly for remote areas, like islands and mountaneous regions. Advances in large-scale wind energy systems, significant cost reductions, more efficient manufacturing techniques and increasing technical experience have contributed greatly to the use of wind energy. Although invented in 1931, the Darrieus turbine did not see extensive development until the 1970's during the worldwide oil crisis where a considerable amount of work has been done with regard to aerodynamic performance prediction methods for vertical-axis wind turbines.;Over the past decade, significant progress has been made in the development of the aerodynamic models for studying vertical-axis wind turbines. Aerodynamic analysis of vertical-axis wind turbines is based on several methods which can be classified into two major categories: momentum models and vortex models. The fundamental objective of all aerodynamic prediction models for the Darrieus rotor is to evaluate the velocity field around the turbine since such knowledge allows the calculation of all the forces on the blades and the power generated by the turbine.;In this study, the investigation of the flow field of vertical-axis wind turbines based on the solution of the steady, incompressible, laminar Navier-Stokes equations in cylindrical coordinates is presented. The flow equations, written in a conservative form, are discretized using a control volume approach on a staggered grid. The effect of the spinning blades is simulated by distributing a time averaged source terms in the ring of control volumes that lie in the path of turbine blades. The computational domaine in cylindrical coordinates system is subdivided into control volumes by series of line orthogonal to r, ;At the first stage, preliminary results dealing with the determination of the world size (the size of the computational domain), the convergence of the numerical model are presented. Then the viscous model, developped here, is used to predict aerodynamic loads and performance for the Sandia 17-m wind turbine. Predictions of the viscous model are compared with both experimental data and CARDAAV aerodynamic code based on streamtube method. According to the experimental results, the analysis of local and global performance predictions by the viscous model show a good agreement. |
