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RFID Senior Project: Uncertainty level and Instrumentation Required
Amanda Mayette, Adam Freund, Matthew Sevey
Due: 2/13/12
Uncertainty Level
With this experiment, the primary concern is with the power generated by the wind turbine. Two
equations can be used to determine the power being generated. Equation 1 determines the power from the
airflow and Equation 2 determines the power from the voltage and current produced by the current.
Since there are two ways of determining the power generated by the wind turbine, there will be two
uncertainties relating to the power. To find the uncertainty of the power from Equation 1, the KlineMcClintock method can be used.
At room temperature the density of air, , is 1.225 kg/m3. The area, A, is the cross sectional area that the
air is passing through and coming in contact with the turbine. Since the turbine blades make a circle when
rotating, the area A is a circle with a radius of 0.58 m. An average wind speed that the wind tunnel can
produce is 9.144 m/s. Now that the variables are defined, the Kline-McClintock method can be applied to
determine the uncertainty of the power.
The uncertainty of the three initially measured values of air density, radius length, and air velocity are
0.025 kg/m3, 0.01 m, and 1.5 m/s respectively. Before the uncertainty of the power can be determined, the
uncertainty of the area A must be determined.
Now that all the variables in Equation 1 have calculated uncertainties, the uncertainty of the power can be
determined.
To find the uncertainty of the power using Equation 2, the Kline-McClintock equation can be used but
with some changes. Since there is no way to determine the voltage or current without running the
experiment, the values for them need to be assumed. For the purpose of finding the uncertainty, the
voltage will be assumed to be about 30 V and the current will be taken as a range from 0-3 A. Since both
values will be recorded using LabView, it can be assumed that the recorded voltage and current will have
an uncertainty of 0.1 V and 0.1 A respectively. Now that the necessary information is known, the KlineMcClintock equation can be used to graph the uncertainty of the power over a range of current at a
constant voltage. Figure 1 shows the uncertainty of the power of the wind turbine.
Wind Turbine Power Uncertainty at 30V
3.016
3.014
Power Uncertainty
3.012
3.01
3.008
3.006
Power Uncertainty
3.004
3.002
3
2.998
0
0.5
1
1.5
2
2.5
3
3.5
Current
Figure 1 - Wind Turbine Power Uncertainty at 30V
Comparing the two uncertainties, it is obvious that the method of finding the power through the voltage
and the current is much more accurate that through the air speed.
Instrumentation Required
To measure all the variables for this experiment, there are only two major pieces of equipment needed.
First there will be an anemometer to measure wind speed, and a DataForth board linked to LabView to
record the voltage and current produced by the wind turbine.