Fluid–structure interaction analysis of a morphing vertical axis wind turbine

There has been much recent interest in the development of Vertical Axis Wind Turbines (VAWTs), especially for use in off-grid or off-shore electricity generation, due to inherent advantages over the more popular horizontal axis types. Although there have been a number of recent attempts to increase efficiency of VAWTs using active and passive blade pitch control strategies, these designs come at an increased upfront cost, detracting from the simplistic allure of the VAWT design. This study investigates the feasibility of a flexible bladed (or morphing) VAWT, wherein individual blades are able to passively adapt to local flow conditions and serve as a pitch control mechanism to increase rotor efficiency. Using a finite volume fluid–structure interaction algorithm, a rigid VAWT is simulated with good agreement with existing experimental data, then compared to several other geometrically identical morphing designs with varying material flexibility. All simulated flexible rotors achieved higher efficiency than the standard (rigid) one, with efficiency gains up to 9.6% for the VAWT geometry investigated herein. The results suggest that the morphing rotor design can have significant advantages over the rigid design particularly in part-load scenarios, and is also likely to increase the self-starting abilities of the VAWT.