CFD & experimentally validated quasi-static trailing-edge morphing-inspired configurations for aerodynamic enhancement of vertical axis wind turbines

Abstract

This study presents a combined numerical–experimental investigation of a quasi-static trailing-edge morphing strategy to enhance the aerodynamic performance of vertical axis wind turbines (VAWTs), with emphasis on power coefficient (Cp) improvement and wake evolution. A hybrid airfoil consisting of 60% rigid and 40% flexible trailing-edge section, based on NACA 2412, is analysed for quasi-static deflections of + 5°, + 10°, and + 15°. Unsteady RANS simulations using the SST transition model are validated against wind tunnel experiments, showing good agreement within 10%. The + 5° configuration achieves a peak Cp of 0.591 at a tip speed ratio (TSR) of 1.5, representing a 47.8% improvement over the baseline (Cp = 0.40). This enhancement is driven by improved flow attachment, delayed dynamic stall, and favourable pressure distribution. In contrast, higher deflections induce stronger adverse pressure gradients, leading to early separation and reduced efficiency. Wake analysis from the present two-dimensional simulations indicates that moderate morphing (+ 5°) reduces velocity deficit and suppresses turbulence intensity in the near wake, while higher deflections enhance shear-layer mixing and accelerate downstream wake recovery. However, these wake characteristics should be regarded as indicative trends because important three-dimensional effects, including spanwise transport, tip-vortex dynamics, and wake meandering, are not captured in the present model and require validation through future three-dimensional numerical and experimental investigations. The results demonstrate that trailing-edge morphing enables simultaneous improvement in energy capture and wake control, offering a practical passive approach for performance optimization of VAWTs.