Computational study on novel circulating aerofoils for use in Magnus wind turbine blades

In most efficient aerofoil sections used in wind turbine blades, the maximum lift to drag ratio hardly reaches 200. Our research obtained higher lift by employing the Magnus effect obtained by circulating symmetrical geometries. First the research study reviews the literature of Magnus effect for circulating cylinders, presents recent progress on BEM (blade element momentum) modelling, and highlights the importance of lift to drag ratio in both Magnus and conventional aerofoil type wind turbine blades. Magnus effect can be produced by a circulating surface of symmetrical aerofoils. However, neither experimental nor computational studies are found in literature for circulating aerofoils. Subsequently, this text presents, a high-resolution computational solver, based on finite-volume TVD (total variation diminishing) scheme, to solve fluid flows around symmetrical NACA0015 aerofoil, where the results are validated against a widely used experimental data. Finally, the circulating NACA0015 aerofoil with various surface treadmill speeds is investigated at different incident angles. The computational results reveal that the lift increases while drag decreases in all cases. The significant lift to drag ratio of 278 is obtained at dimensionless treadmill speed of 2 at incident angle of 10°. The flow features around this circulating aerofoil, along with the need for additional experimental research, is described.