Modeling Vertical-Axis Wind-Turbine Performance: Blade-Element Method Versus Finite Volume Approach

Vertical-axis wind turbines offer an inherently simpler design than horizontal-axis machines, and their lower blade speed mitigates safety and noise concerns. Although vertical-axis turbines do offer significant operational advantages, development has been hampered by the difficulty of modeling the aerodynamics involved, along with their rotating geometry. This paper presents results from a simulation of a baseline vertical-axis wind turbine computed using Star-CCM+, a commercial finite volume code, and compares them with data obtained from a multiple-streamtube model. Emphasis was placed on the dynamic stall characteristics and wake production, which have the greatest influence on turbine performance. A model was developed to replicate the blade-wake interactions common at higher tip-speed ratios and was found to greatly improve the accuracy of the blade-element momentum model.