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Moving surface boundary-layer control with application to autonomous underwater vehicles Den Hertog, Vincent R.
Abstract
Moving Surface Boundary-layer Control (MSBC) is a technique to delay separation and control circulation over bodies in fluid flow through momentum inj ection. In the past, rotating cylinders have been successfully used as the moving surface elements on both bluff and streamlined bodies. On tractor-trailer trucks, for example, rotating cylinders have been shown to lower the drag by reducing the size of the separated wake. For aerofoil profiles, momentum injection has lead to dramatic improvements in lift and drag. With this as background, the present study explores fluid dynamics of two different configurations in the presence of MSBC and assesses their potential in improving the performance of the control surfaces (hydroplanes) used on Autonomous Underwater Vehicles (AUVs). To that end, a carefully planned experimental program is conducted using two-dimensional models in a closedcircuit wind tunnel. Surface pressure distribution results are used to characterize circulation and separation effects and explain trends exhibited by the force, moment and centre of pressure data. In the first configuration, a wedge-shaped profile is integrated with a rotating cylinder at the leading edge. The momentum injection moves the boundary-layer separation point downstream resulting in high levels of lift with a profile that is simpler and less expensive to construct than a regular aerofoil. The lift, drag and moment characteristics are measured for a family of wedge profiles with three different thickness-to-chord ratios. The results are compared with those for a symmetrical aerofoil with the MSBC. Results suggest that, among the configurations tested, the wedge-aerofoil with a thickness ratio of 16% is particularly suited to an application where a high level of constant lift is required in one direction, e.g. a depressor wing on a towed vehicle. The second configuration considers a symmetrical aerofoil equipped with a rotating cylinder at its trailing edge. Such a system is capable of generating a significant amount of lift, even at zero angle of attack through a circulation control mechanism related to the Magnus Effect. The lift is controlled by the speed and direction of rotation of the cylinder. This is shown to be an attractive replacement for the bi-directionally deflecting hydrofoils found on many AUVs. The study also shows that the power required for the momentum injection is rather modest, and cavitation is not a problem in its application to most AUVs.
Item Metadata
Title |
Moving surface boundary-layer control with application to autonomous underwater vehicles
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1999
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Description |
Moving Surface Boundary-layer Control (MSBC) is a technique to delay separation and
control circulation over bodies in fluid flow through momentum inj ection. In the past, rotating cylinders
have been successfully used as the moving surface elements on both bluff and streamlined bodies. On
tractor-trailer trucks, for example, rotating cylinders have been shown to lower the drag by reducing
the size of the separated wake. For aerofoil profiles, momentum injection has lead to dramatic
improvements in lift and drag.
With this as background, the present study explores fluid dynamics of two different
configurations in the presence of MSBC and assesses their potential in improving the performance of
the control surfaces (hydroplanes) used on Autonomous Underwater Vehicles (AUVs). To that end,
a carefully planned experimental program is conducted using two-dimensional models in a closedcircuit
wind tunnel. Surface pressure distribution results are used to characterize circulation and
separation effects and explain trends exhibited by the force, moment and centre of pressure data.
In the first configuration, a wedge-shaped profile is integrated with a rotating cylinder at the
leading edge. The momentum injection moves the boundary-layer separation point downstream
resulting in high levels of lift with a profile that is simpler and less expensive to construct than a regular
aerofoil. The lift, drag and moment characteristics are measured for a family of wedge profiles with
three different thickness-to-chord ratios. The results are compared with those for a symmetrical aerofoil
with the MSBC. Results suggest that, among the configurations tested, the wedge-aerofoil with a
thickness ratio of 16% is particularly suited to an application where a high level of constant lift is
required in one direction, e.g. a depressor wing on a towed vehicle.
The second configuration considers a symmetrical aerofoil equipped with a rotating cylinder
at its trailing edge. Such a system is capable of generating a significant amount of lift, even at zero angle
of attack through a circulation control mechanism related to the Magnus Effect. The lift is controlled
by the speed and direction of rotation of the cylinder. This is shown to be an attractive replacement for
the bi-directionally deflecting hydrofoils found on many AUVs.
The study also shows that the power required for the momentum injection is rather modest, and
cavitation is not a problem in its application to most AUVs.
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Extent |
8945545 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-06-25
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0099327
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1999-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.