# lecture04 - Wind Energy II Air density Wind speed Wind...

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ENGRI 1290 1 Wind Energy II Air density Wind speed Wind power density

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ENGRI 1290 2 Lecture’s objectives • Computing wind power density • Learning what physical conditions change the air (volumetric mass) density • Discovering why wind speed widely varies around the world and the USA
ENGRI 1290 3 Wind kinetic energy near a turbine A d A u M M d v u v Turbine A v A flow of air of mass M moves from upstream (u) to downstream (d) passing through a turbine at a velocity v. This flow can be seen as a stream of air limited by streamlines. The streamlines represent an imaginary pipe surrounding the flow. What is the kinetic energy of the air passing through the turbine ? 2 k 1 EM v 2 Since we are trying to find the kinetic energy near the turbine we need to transform M using the turbine characteristics (A, v). First we use a local value for the air mass … 2 k 1 EV v 2  Since the volume of air at the turbine is AL and L=vt we get  2 k 1 EA v t v 2 which we rewrite as 3 k 1 v t 2 upstream downstream

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ENGRI 1290 4
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## This note was uploaded on 09/14/2011 for the course ENGRI 1290 taught by Professor Gourdain during the Fall '10 term at Cornell University (Engineering School).

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lecture04 - Wind Energy II Air density Wind speed Wind...

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