Load Reduction Using Rapidly Deployed Trailing-Edge Flaps
Author(s)
Frederick, Mark
Type
Thesis
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.
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.
Date Issued
2008-12
Date Awarded
2009-10
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Creator
Frederick, Mark
Publisher Department
Department of Aeronautics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)