Exploration of the rotational power consumption
of a rigid flapping wing
of a rigid flapping wing
File(s)
Accepted version
Author(s)
Truppel, Michael
Rossi, Lionel
Type
Journal Article
Abstract
The development of Micro Air Vehicles with
flapping wings is inspired from the observation and study
of natural flyers such as insects and birds. This article
explores the rotational power consumption of a flapping
wing using a mechanical flapper at Re ^ 4,500. This
mechanical flapper is simplified to a 2D translation and a
rotation in a water tank. Moreover, the wing kinematics are
reduced to a linear translation and a rotation for the purpose
of our study. We introduce the notion of non-ideal flapper
and associated non-ideal rotational power. Such non-ideal
devices are defined as consuming power for adding and
removing mechanical power to and from the flow,
respectively. First, we use a traditional symmetrical wing
kinematic which is a simplified kinematic inspired from
natural flyers. The lift coefficient of this flapping is about
CL ^ 1.5. This symmetrical wing kinematic is chosen as a
reference. Further, wing kinematics with asymmetric
rotations are then compared with this one. These new
kinematics are built using a differential velocity defined
according to the translational kinematics, a time lag and a
distance, rkp. The analogy of this distance is discussed as a
key point to follow along the chord. First, the wing kinematics
are varied keeping a similar shape for the profiles of
the angular velocity. It is shown that when compared to the
reference wing kinematic, a 10% reduction in the rotational
power is obtained whilst the lift is reduced by 9%. Second,
we release the limitation to a similar shape for the profiles
of the angular velocity leading to a novel shape for the
angular velocity profile named here as ‘‘double bump’’
profile. With these new wing kinematics, we show that a
60% reduction in the non-ideal rotational power can be
achieved whilst the lift coefficient is only reduced by 1.7%.
Such ‘‘double bump kinematics’’ could then be of interest
to increase the endurance of Micro Air Vehicles.
flapping wings is inspired from the observation and study
of natural flyers such as insects and birds. This article
explores the rotational power consumption of a flapping
wing using a mechanical flapper at Re ^ 4,500. This
mechanical flapper is simplified to a 2D translation and a
rotation in a water tank. Moreover, the wing kinematics are
reduced to a linear translation and a rotation for the purpose
of our study. We introduce the notion of non-ideal flapper
and associated non-ideal rotational power. Such non-ideal
devices are defined as consuming power for adding and
removing mechanical power to and from the flow,
respectively. First, we use a traditional symmetrical wing
kinematic which is a simplified kinematic inspired from
natural flyers. The lift coefficient of this flapping is about
CL ^ 1.5. This symmetrical wing kinematic is chosen as a
reference. Further, wing kinematics with asymmetric
rotations are then compared with this one. These new
kinematics are built using a differential velocity defined
according to the translational kinematics, a time lag and a
distance, rkp. The analogy of this distance is discussed as a
key point to follow along the chord. First, the wing kinematics
are varied keeping a similar shape for the profiles of
the angular velocity. It is shown that when compared to the
reference wing kinematic, a 10% reduction in the rotational
power is obtained whilst the lift is reduced by 9%. Second,
we release the limitation to a similar shape for the profiles
of the angular velocity leading to a novel shape for the
angular velocity profile named here as ‘‘double bump’’
profile. With these new wing kinematics, we show that a
60% reduction in the non-ideal rotational power can be
achieved whilst the lift coefficient is only reduced by 1.7%.
Such ‘‘double bump kinematics’’ could then be of interest
to increase the endurance of Micro Air Vehicles.
Version
Accepted version
Date Issued
2011
Citation
Experiments in Fluids, 2011, pp.1-15
ISSN
0723-4864
Publisher
Springer
Start Page
1
End Page
15
Journal / Book Title
Experiments in Fluids
Copyright Statement
© Springer-Verlag 2011. The final publication is available at www.springerlink.com