Question

At a wind speed of 45 mph, a wind turbine placed on a hill with air density of 1.2 kg m^-3 generated power of 3.5 MW. Calculate the length of the blade on the wind turbine?

Answer 1

Ideal case, assuming 100 % efficiency.
Power generated, P = 1/2 Av³
Where is the density of air, A is the area of the blades and v is the wind velocity.
v = 45 mph = 20.12 m/s
3.5 x 10⁶ = 0.5 x 1.2 x A x (20.12)³
A x 9769.18 = 3.5 x 10
A = (3.5 x 10) / 9769.18
= 358.27
A = R² = 358.27
R = SQRT[358.27/]
= 10.68 m