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General description
In September 2003, IIHR
commissioned LaVision GmBH to design and fabricate a towable,
three-dimensional particle image velocimetry (3DPIV) system for
phase-averaged flowfield measurements around a maneuvering surface
combatant ship model. The 3DPIV system consists of a 120 mJ Nd:Yag
laser, submerged lightsheet generator, two 1600x1200 pixel
cross-correlation cameras fitted with 50 mm f/1.8 lenses, and computer
and software for data acquisition and reduction of piv recordings. The
lenses are equipped with motors for automatic remote focusing and
aperture adjustments. The camera bodies are equipped with motors for
automatic remote Scheimpflug angle adjustments. Each camera is housed
in a separate, submerged enclosure downstream of the measurement area to
minimize effects of flow past the underwater parts at the measurement
area. The cameras are arranged in a specific geometry with equal
standoff distances between the enclosures and the measurement area, 35°
of separation between cameras, and a 22° angle between camera #1 and the
tank axis to provide clearance with the model and avoid an extremely
shallow angle between camera #2 and the cross plane. A minimum
separation angle of 30° between cameras is maintained to ensure good
measurement quality. The laser, lightsheet generator, and camera
enclosures are assembled on a lightweight matrix of aluminum extrusions
for adjustability and rigidity. For combned PMM/3DPIV measurements,
synchronization of the PMM motions and the 3DPIV data acquisition is
achieved with an IIHR-built PIV synchronizer. The 3DPIV system
rides on the PMM strongback and is maneuvered with the ship model for
measurements in the ship-coordinate system.
System specifications
Designed and built:
2003-2004
Installation: May 2004
Tests: Towed,
phase-averaged 3DPIV with PMM
Measurements: 3D
velocities and Reynolds stresses
Laser: Big Sky,
dual-headed CFR 120 mJ Nd:Yag
Cameras: 2
Imager Pro 2M (1600x1200 pixel)
Lenses: 2 Canon
EOS f/1.8, 50 mm
Focus, aperture, Scheimpflug
angle: automatic
Measurement area:
20 cm x 15 cm
Typical spatial
resolution: 20 vectors/cm2
Data rate: ~ 5
Hz
Analog data: 8
channels synchronously with the 3DPIV
Configuration:
asymmetric; cameras are positioned downstream of measurement
area
Software:
LaVision DaVis v7.1 |
Companies
LaVision GmbH
Anna-Vandenhoeck-Ring 19
D-37081 Goettingen
Germany
Phone: +49-(0)551-9004-0
Fax: +49-(0)551-9004-100
e-mail:
info@lavision.de
LaVision Inc.
301 W. Michigan Ave.
Suite 403
Ypsilanti, MI 48197
USA
Phone: (734) 485-0913
Fax: (240) 465-4306
e-mail:
sales@lavisioninc.com
URL:
http://www.lavision.com
Big Sky Laser Technologies, Inc.
P.O. Box 8100
Bozeman, MT 59715-2001, USA
Phone: (406) 586-0131
Fax: (406) 586-2924
URL:
http://www.bigskylaser.com
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Measurement sytems
