Improving vertical-axis turbine efficiency with chordwise actively deforming blades

This study investigates the effects of employing actively deforming airfoils on the performance of vertical-axis turbines. Two-dimensional unsteady Reynolds-averaged Navier–Stokes simulations were conducted on a single-bladed H-type Darrieus vertical-axis turbine model equipped with a chordwise deforming NACA0015 airfoil. During the rotation cycle, two-thirds of the airfoil’s chord, corresponding to the trailing edge, undergoes prescribed deformations, while the remaining one-third remains undeformed. An overset mesh technique, combined with radial basis function morphing, is used to manage the deformation and movement of the mesh. The study explores the impact of deformation amplitudes and timings on the turbine’s efficiency at various tip-speed ratios. Preliminary simulations evaluating the effect of steady deformation amplitudes on the instantaneous power coefficient are used to identify promising active deformation patterns. Subsequently, the turbine’s performance is assessed using simulations involving two-phase active deformation patterns. The results show a 3.55% efficiency improvement at a near-optimal tip-speed ratio with actively deforming airfoils. More significant relative improvements are observed at low tip-speed ratios, while higher tip-speed ratios yield only marginal benefits.