URGENT! Please help me!! about wind turbine and solving the formula!!!?

Question

The amount of wind energy harnessed per sec can be worked out by the formula: (rA x (v cube) ) / 2 r=density of air, A = the area swept out by turbine blades, v = wind speed

By finding out the average wind speed and length of the turbine blades, work out the amount of energy each wind turbine can produce in 3 hour?

In reality, the actual amount of wind energy produced in is less than that calculated. WHY?

Answer 1

If you know the length of the turbine blades, l, the area can be calculated as pi*l square (the formula for calculating the area of a circle from the radius).

The power (in watts) may therefor be calculated with the following formula:

P = r * pi * l * l * v * v * v /2

where l is the length of the blades, pi is appr. 3,1415, and r appr. 1,2 kg per sq m.

One watt is one joule per second, which means that in three hours the energy produced is:

P * 10 800 (number of seconds in three hours)

This is the amount of energy produced in theory. In reality though, you will always have losses, like mechanical losses in the turbine and electrical losses in the generator. Therefor, the actual energy produced will always be less than the theoretical value.