3B Scientific Laminar Flow Apparatus - Manual (Page 3)

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intervals, as in front of the object (refer to fig. 3 a, b,
c).
Result: The flow object causes the flow to change its
direction in its close proximity. The velocity of the
flow increases and the streamlines move closer to
each other. Behind the object, the velocity of the
flow reduces. The interval between the streamlines
increases. Finally, the lines are parallel.
6.3. Streamline curve around a wing profile of an
aeroplane
• Carry out the experiment using a sheet of velour
paper with a wing-shaped cut-out.
Above the wing, the streamlines change their direc-
tions greatly and are compressed. Therefore, the
flow velocity is high. Below the wing, the flow veloc-
ity only increases slowly. Repeat the experiment with
the velour paper sheet, on which the angle of attack
is larger than zero. In the top area, the directions of
the streamlines change greatly. Below the wing pro-
file, the streamlines initially run in its direction and
are then drift down (refer to fig. 4 a, b).
Result: The streamline image of a wing profile shows
a great increase of velocity above the profile due to
the narrow streamlines. Below the wing, the fluid
flows in the direction of the wing when the angle of
attack is positive and then drifts down.
6.4. Streamline curve at a narrow point
• Use the velour paper sheet with the cut-outs on
both sides.
When the flow reaches the narrow point, its velocity
increases. The streamlines move together. After pass-
ing the narrow point, the streamlines move apart, so
that the flow shows its initial streamline curve (refer
to fig. 5).
Result: At a narrow point, the interval between the
streamlines reduces. The flow velocity increases
greatly. After the narrow point, the intervals between
the streamlines increase. The flow velocity reduces.
Fig. 2 Fig. 3 a, b c