scholarly journals Computational Fluid Dynamics Study of a Modified Savonius Rotor Blade by Universal Consideration of Blade Shape Factor Concept

Author(s):  
Abdel-Fattah Mahrous

This work aims to investigate computationally the performance of Savonius vertical axis wind turbine having a new design feature for its blade geometry. The proposed design is based on a universal consideration of blade shape factor concept for the Savonius rotor blade. A blade shape factor ranges from zero to infinity, or vice versa, is considered in a single blade of the modified Savonius rotor. This means that each point in the two-dimensional blade profile of the suggested blade design has a single value of blade shape factor that is defined based on the dimensions of conventional semi-circular blade. The computational results of the proposed blade shape design, having blade shape factor varying from infinity to zero, showed an improvement in turbine performance as compared to conventional blade shape design. Moreover, increasing the operating range of Savonius wind turbine is expected.

2010 ◽  
Vol 1 (08) ◽  
pp. 719-724 ◽  
Author(s):  
G. Colley ◽  
R. Mishra ◽  
H.V. Rao ◽  
R. Woolhead

Author(s):  
Zhenlong Wu ◽  
Yihua Cao

Rainfall is a common meteorological condition that wind turbines may encounter and by which their performance may be affected. This paper comprehensively investigates the effects of rainfall on a NACA 0015 airfoil which is commonly used in vertical axis wind turbines. A CFD-based Eulerian–Lagrangian multiphase approach is proposed to study the static, rotating, and oscillating performances of the NACA 0015 airfoil in rainy conditions. It is found that for the different airfoil movements, the airfoil performance can seriously be deteriorated in the rain condition. Rain also causes premature boundary layer separations and more severe flow recirculations than in the dry condition. These findings seem to be the first open reports on rain effects on wind turbine performance and should be of some significance to practical design.


2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Alexandrina Untaroiu ◽  
Houston G. Wood ◽  
Paul E. Allaire ◽  
Robert J. Ribando

Vertical axis wind turbines have always been a controversial technology; claims regarding their benefits and drawbacks have been debated since the initial patent in 1931. Despite this contention, very little systematic vertical axis wind turbine research has been accomplished. Experimental assessments remain prohibitively expensive, while analytical analyses are limited by the complexity of the system. Numerical methods can address both concerns, but inadequate computing power hampered this field. Instead, approximating models were developed which provided some basis for study; but all these exhibited high error margins when compared with actual turbine performance data and were only useful in some operating regimes. Modern computers are capable of more accurate computational fluid dynamics analysis, but most research has focused on horizontal axis configurations or modeling of single blades rather than full geometries. In order to address this research gap, a systematic review of vertical axis wind-power turbine (VAWT) was undertaken, starting with establishment of a methodology for vertical axis wind turbine simulation that is presented in this paper. Replicating the experimental prototype, both 2D and 3D models of a three-bladed vertical axis wind turbine were generated. Full transient computational fluid dynamics (CFD) simulations using mesh deformation capability available in ansys-CFX were run from turbine start-up to operating speed and compared with the experimental data in order to validate the technique. A circular inner domain, containing the blades and the rotor, was allowed to undergo mesh deformation with a rotational velocity that varied with torque generated by the incoming wind. Results have demonstrated that a transient CFD simulation using a two-dimensional computational model can accurately predict vertical axis wind turbine operating speed within 12% error, with the caveat that intermediate turbine performance is not accurately captured.


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