Load Reduction Using Rapidly Deployed Trailing-Edge Flaps

Abstract

This thesis details investigations into the aerodynamic properties of a small, rapidlyactuated, actively controlled trailing-edge ap and the potential of such a device to alleviate the unsteady loading experienced by wind turbine blades due to atmospheric turbulence and the atmospheric boundary layer, although such a device would have potential applications in other elds such as rotorcraft. The main goals of this work were to investigate whether aerodynamic loadings could in fact be alleviated by the use of a small trailing-edge ap using only measurements of the unsteady lift on the wing as a control input and to assess such a device's capacity to reject atmospheric disturbances with both numerical and experimental work, carried out in the Aeronautics Department at Imperial College London. The numerical work covered in the thesis comprises the results of linear and nonlinear aerodynamic and control simulations (e.g. PID, LQG controllers) and the results of computational uid dynamics (CFD) simulations using the commercial package FLUENT. The thesis also lays out the results obtained from testing an experimental prototype in the Hydrodynamics Laboratory in the Aeronautics Department. This prototype successfully rejected intentionally introduced ow disturbances from the vortex street of a square block upstream of the wing and the application of control provided a very signi cant reduction in the unsteady loading experienced by the wing. The ndings show the potential of this method of load control for the rejection of unsteady aerodynamic loading by the sole use of measurements of the wing loading and this has been demonstrated both theoretically and experimentally. The work is closed with a conclusion and suggestions for future research proposals.