Experimental and Fluid Structure Interaction analysis of a morphing wind turbine rotor

•We experimentally investigate a flexible horizontal axis wind turbine.•We model the turbine using finite-volume fluid-structure interaction.•Flexible bladed design increases both efficiency and range of operation.•Efficiency increases are attributed to passive deflection of blades.

Active control of blade pitch for wind turbines is known to increase efficiency, especially for part and over-load operation. An unfortunate consequence of this practice is added upfront and maintenance costs, making these schemes economically viable only in large scale applications. This study investigates a novel concept for wind turbine design, in which the blade is purposefully built of a flexible material which can passively adapt its geometry according to local wind conditions. This design concept therefore acts as a low cost, simplistic passive pitch control mechanism. Using a finite-volume fluid–structure interaction solver, the aeroelastic response of such a turbine is analyzed and compared to experimental data collected from wind tunnel tests as part of this project. The results indicate that the flexible rotor is markedly superior to a geometrically identical rigid one in terms of the size of its operational envelope as well as average and maximal torque production. Using post-processing tools, the performance improvements are attributed to passive deflection of the airfoil, which act to delay blade stall and drastically change surface pressure distribution to improve turbine performance.