10: LAB WIND TUNNEL EXPERIMENTS: WIND AND PRESSURE
WITH REAL WORLD APPLICATION
QUESTION 1: Our experimental value of n was less than 2. The reason our value of n
was less than 2 could have been because our pressure readings could have been lower
than true pressure readings which results in a lab error making n less than m\2. The
problems that may have caused that could have caused that could have been involving the
Pitot tube and the manometer probe. We could have easily not placed it in the exact
position for certain angles at the top of the Quonset Hut. The lines for the angles were
hand draw and some were faded so as humans, whether those lines were like that or not,
we could easily fail at putting the tube in the exact position. We could have also been too
quick to read the final pressure reading and write down the first reading we see or
estimate the right decimal after the number since the pressure readings do not tend to stay
still. We also could have messed up the manometer in some way and failed to screw the
tube on tight enough.
QUESTION 2A: Our vehicle was a Recycling Truck.
QUESTION 2B: The wind speed that blew the Recycling truck out of the tunnel was
when it reached 5.6 m/s.
QUESTION 2C: Based on our experiment, we can conclude that the wind speed required
to move or turn over a full-sized vehicle would be 22.4 m/s. We can conclude that
because a real car may weigh 1,200kg, which is 40,000 times more than a 30 g model.
According to the lab instructions, if that is true, the force required to move a real car must
be 40,000 greater than the force needed to move a model.
QUESTION 2D: The wind speed in miles per hour to overturn a vehicle would be 51.52
mph. We can conclude that because to figure out speed in miles per hour, you multiply
the wind speed in m/s by 2.3. However since we are determining the wind speed in mph
to overturn a real vehicle rather than a model, we do that process and multiply it by
40,000.
QUESTION 2E: Two kinds of storms that could produce this speed of wind would be
tropical storms and stage one, two, three, four and five hurricanes according to the SaffirSimpson Hurricane Scale. Also included would be tornadoes.
QUESTION 2F: Our predicted wind speed that would turn over a full-sized vehicle of
51.52mph seems pretty reasonable, yet a little bit low. For one reason, it seems to
compare pretty well with the other groups results in our lab. The prediction for the van
was 24.3 mph and the prediction for the VW bug was 89.24 mph so ours wasnt far off
from that range but it did seem a little low for a truck compared to a VW bug. Also, I
looked up the wind speed that would overturn a car on weather.com and other sights just
to double check if 51.52mph was anywhere close and the necessary wind speed to
overturn a minivan was 130mph.
QUESTION 2G: There are some differences between our model in the wind tunnel and
the real thing. One difference is the angle car the was at. Our model was on flat ground
while a real vehicle could be going up a hill, parked on a slope, etc. Another difference is
that our model car was placed sideways and the wind was blowing directly at the side of
it while a real vehicle could be facing any direction compared to the wind. Another
difference is that our model was still while a real vehicle could be driving at variable
speeds during a storm with high wind speeds. The final difference between our model
and a real vehicle is size and space. Our model was small and confined within one wind
tunnel while a real vehicle is much larger and could be in any space with other things
surrounding it.
QUESTION 3: According to our ATOC 1070 class, the VW bug seemed to require the
highest wind speed to be overturned with a wind speed of 89.24. The van seemed to
require the lowest wind speed with a speed of 24.3. The vehicles require different wind
speeds because of the sizes, shapes, density and make of the vehicles. If I were to be
driving on Highway 93 south of Boulder where winds can exceed 100mph, I would rather
drive the VW bug (even though I think bugs are weird) because it requires the highest
wind speed to overturn it. Therefore, a VW bug would give me the highest chance of
driving to my destination without dying.
QUESTION 4:
The part of the hut that would fly off first in high winds would be the sides of the roof
facing opposite of the wind direction at 30 degrees. The reason for this is that according
to the graph, at 30 degrees, the pressure was highest (at 19 Pa) while right after at 45
degrees and before at 15 degrees, the pressure was lower along with every other pressure
at all other angles. The angle with the highest pressure would blow off first because
where pressure is the bulk of air molecules hitting a surface and at 30 degrees, it seems to
have the highest pressure.
QUESTION 5A: Our measured wind speed for this part of the experiment was 4.7 m/s.
QUESTION 5B: The speed at miles per hour is 10.81 mph.
QUESTION 5C: After multiplying the speed at miles per hour by 10, we get 108.1 mph.
The kinds of storms that produce this wind are stage two hurricanes and moderate
tornados.
QUESTION 5D: The greatest negative pressure in Pascals that we measured on the hut
was at -33 Pa.
QUESTION 5E: After multiplying the greatest negative pressure by 100 because of the
speed it was at, the new greatest negative pressure is -3,300 Pa.
QUESTION 5F: After multiplying the new greatest negative pressure by 0.021, we get
the high wind pressure in pounds per square foot, which is 69.3 psf.
QUESTION 5G: A 10 x 10 foot section of the roof would be 100 square feet. The force
exerted on this section of the roof would be -33,000 Pa.
QUESTION 5H: The force exerted on the roof is would be much less than the weight of
the roof because the weight of the roof would be 6,930 after multiplying 100 by the psf of
69.3.
CONCLUSION: