SOURCES
OF ERROR
l1.
Setup of the experiment.
The
fact that the gap between the different positions where the prove rests is
set to 4mm, a smaller range of motion would provide a better reading,
specially when finding the stagnation point.
l2.
The reference point for the Pilot-Static Tube.
Due
to the fact that readings are only taken at distances x/D = 5 and x/D =
10, this calls for a lot of interpolation between data points, and also, a
great amount of interpretations and assumptions are to be made based on
the overview data given.
l3.
Error in calculating a accurate reading for the equipment.
Due
to the fact that the person reading the data had to interpolate from the
varying data output from the Voltmeter, this also allows place for error
due to averaging.
l4.
Calculations.
The
error due to error propagation in calculations and in the accuracy and
reading of the equipment seemed to be minor compared to the error that
could occur in the setup of the experiment.
One major source of error could have been the pitot-tube axis not
being in alignment with the velocity vector.
Another source of error could have been at the beginning when the
center of the cylinder was found to use as a reference point for all
further measurements.
The graph of Cp showed one value that seemed to be far from the
trend shown by the other points, this is most likely attributed due to a
bad pressure reading at the 45-degree pressure port.
The error was calculated using the RMS method and was found to be
approximately ±0.5
for the Cd values.
The error in the pressure readings was approximately ±0.69
Pascals.
The only other value used in the velocity calculation was density
(no error) and these led to quite small error values in velocity and thus
drag force.
From this, we can see that the errors that cannot be mathematically
accounted for were more likely to cause problems.
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