Firstly, the
wing was configured at 10o of pitch and the inlet velocity of 75
knots was chosen. At this speed, the airflow remained attached and the flow
lines were constant over the length of the wing.
The inlet velocity was then changed to a lower speed- 65 knots. It was
discovered that at this airspeed, the flow of air over the wing began to stall.
The velocity plot shown by image 6.2a illustrates that
at a distance of 3 metres from the wing root, the airflow started to separate
from the upper surface of the wing, and the towards the trailing edge of the
wing, the air begun to circulate at a lower speed. Any further reduction in the
airflow over the wing would reduce the amount of lift produced by the wing and
also further the stall.
 |
| Image 6.2a |
The angle of
attack of the wing was increased to 20o above the horizon and an
inlet velocity of 70 knots was selected. The resultant plot of image 6.2b shows the wing section (7 metres from the root, to
the wing tip) established within a stall. The airspeed was then reduced to 60
knots, which caused the whole wing to enter into the stall as shown in image
6.2c. This shows that the
critical airspeed for the stall to occur is between 60 and 70 knots.
 |
| Image 6.2b |
 |
| Image 6.2c |
Next, the pitch
of the wing section was increased up to 30o angle of attack and a
starting inlet velocity of 60 knots was chosen. The fluid flow simulation was
then run again and the resultant velocity flow plot was produced, as
illustrated by image 6.2d.
 |
| Image 6.2d |
The velocity
plot shown in image 6.2d is position at a distance of 6 metres from the root of
the wing, and from this point towards the wing tip the airflow had begun to
stall over the upper surface. The inlet velocity was then lowered to 50 knots,
in order to ascertain at what speed the whole wing would stall. From the
simulation, the velocity plot as shown by image 6.2e was produced. This shows
that at this lower speed the area closest to the wing root had stalled. The
critical airspeed at which the stalling of the wing occurs is therefore between
50 and 60 knots.
 |
| Image 6.2e |
No comments:
Post a Comment