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Wind AnalysisWind information was sourced from AWS Truewind windNavigator™ (http://nyswe.awstruepower.com/). AWS Truewind windNavigator™ was used by the P11401 team for their analysis, as well as in the Renewable Energy Systems course offered at RIT.
AWS TruewindThe AWS Truewind site allows you to select a location and get average wind speeds at various heights. The results are below for a spot within RIT. Moving the cursor around within RIT's campus changes the wind speed values minimally.
With these given average wind speed values, the friction coefficient (alpha) could be found by using the equation V1/V2 = (H1/H2)^(alpha). V1 and V2 being any of the two given average wind speeds, and H1 and H2 being the respective heights of those wind speeds. Since alpha is the only unknown, it can be solved for. It came out to be 0.2611, which is typical for a low woodlands, slightly hilly area.
(4.47[m/s]/4.74[m/s]) = (24.4[m]/30.5[m])^(alpha)
alpha = 0.2611
Then, with any one given average wind speed, its respective height, and the calculated alpha, any user input height could be put to the same equation. Now the only unknown is now the velocity at the user input height, which can be solved for.
(V1[m/s]/4.74[m/s]) = (3[m]/30.5[m])^(0.2611)
V1 = 2.59 m/s
The 2.59 m/s value is the average annual wind speed at 3 meters above the ground for the RIT area.
To check that value, a typical assumption for wind speed distributions is to use Rayleigh's Distribution. The equation for this can be seen in the image below, along with the (condensed and converted to SI units) AWS Truewind data and calculated alpha.
To make sure this Rayleigh Distribution was correct, average wind speeds were broken up into "bins" by every 1 m/s. Hours per year at that wind speed were then calculated using the Probability at V equation above. An average was then taken by summing up weighted V and dividing by the 8760 hours that occur in a year. This value was also found to be 2.59 m/s. The data and plotted wind speeds vs. hours at speed per year are shown below.
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