Analysis of Vertical Axis Wind Turbine Aerodynamics by Using a Multi-Fidelity Approach

This paper compares several methods for predicting the vertical axis wind turbine's aerodynamic performance, loading patterns as well as wake system behind the turbine. Three distinct aerodynamic prediction methodologies are implemented and compared with each other. One method is a low complexity analysis that improves the double-multiple streamtube model which is based on the traditional Blade Element Momentum theory. Another method is a medium complexity analysis which utilizes a potential flow model based on the calculation of the velocity field through the influence of the near wake system by applying the the three-dimensional panel method to the rotorł whole blade analysis. The last method is a high complexity analysis that utilizes the overset grid based full computational fluid dynamics method, in which each blade of the turbine will be modeled by using body conforming structured curvilinear meshes. Two different test cases are studied in order to highlight and characterize the prediction capabilities of all the approaches. The computational results of the aerodynamic loads acting on the rotor blades and whole turbine's power coefficient, which are obtained by three approaches, will be compared with the experimental data. Furthermore, the wind deficits generated by an isolated turbine are investigated by utilizing the subset of methodologies that allow for probing of flow field information such as velocity magnitude contours and wake trajectory behind the turbine. Finally, the advantage and disadvantage of each method are discussed so that the appropriate model can be applied to solve the desired engineering cases in more efficient ways.