The Institute of Fluid Mechanics at the Technical
University of Braunschweig is engaged in a
research project studiyng high Iift wing profiles for
aviation. The aerodynamics are visualized using
particle image velocimetry. The mechanical
deformations of the carbon fiber profile due to the
aerodynamic forces need alsotobe measured.
The measurement method of choice should not
influence the air flow within the windtunnel.
Video photogrammetry requires only 0.1 mm thin
retroreflective, circular markers that do not
interfere with the flow, making it ideal for the task.
The number of markers is unlimited, so that a
large number of deformation values can be
acquired across the width and length of the
The cameras and lighting were placed outside the
wind tunnel to avoid obstructing the airflow. The
calibration object was shown to the cameras from
the within the wind tunnel to compensate for the
refraction error caused by the Observation
Figure 1 shows the flow conditions in the wind
tunnel, figure 2 visualizes the green Iaser light of
the Particle Image Velocimetry, figure 3 depicts
the cameras mounted above the wind tunnel,
figure 4 is a schematic representation of the
overall structure and figure 5 gives an insight into
the interior with the targets on the wing profiles.
Figures 6 and 7 show the measurement results.
As expected, the deformation increases
quadratically with the flow velocity. At the second
highest flow velocity of 45 m I s, resonance
vibrations become apparent in the deformation
Using video photogrammetry comprehensive and
Figure 4: Windtunnel as a 3D Model
precise 30 measurement data could be obtained Figure 5: lnterior of the wind tunnel
within only a few hours and without substantial with optical markers.
changes to the wind tunnel.
We would like to thank the Institute for Fluid
Mechanics of the TU Braunschweig for the good
cooperation and the kind permission to use the
images shown on the right.