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Here is a physics/engineering question.
From various texts, the theoretical maximum power transfer from wind toelectrical power is cubic in wind speed and also depends on the area swept
by the rotors. The cubic part comes from the KE which is of course
quadratic in speed but with the added linear factor of wind mass. All
that's fine, but when you look at the power curves of real wind turbines,
you see 'S' curves, with little power generated at low speed and levelling
to some max power at high speed. However, the curves look pretty linear
from the 'cut in' to the 'cut out' wind velocities--slopes greater than one.
We have the Pasco Energy Transfer Generators and are putting together a wind
energy lab, but we're also seeing a linear dependency (using a three speed
fan). Not sure I understand the linearity and certainly not sure how to
approach my Energy class (gen-ed students) with anything other than 'turbine
design is complex and the actual power transfer is a function of each
individual device'. Any insights would be appreciated.
Slide 11 above shows some typical power curves--many others can be found