1. A land based wind turbine has a has hub height of 150 meters. The weight of the machine

head and rotor is 200 metric tons. Other assumptions you can make

a. Operating range of rotor 4 to 15 RPM

b. 350 MPa yield strength of steel

c. Young's modulus of 210 GPa

d. Tower outside Diameter of 5.5m, at the base tapering to 3.0 m at the top.

e. Wall thickness = 25mm, made of steel

f. This is an upwind rotor

Estimate the following:

b.

a. The static (0 RPM) stress at the bottom of the tower including the tower weight.

If the rotor thrust load is 50,000 N at a particular operating regime, what is net

compressive stress on the downwind side of the tower.

c.

If the tower natural frequency can be expressed as

3EI

fo

where I=(Doutside - Dinside)

277 (0.23mtower+mnacelle) L³

Generate a simple Campbell diagram with 1 per and 3 per revolution lines and

confirm that the turbine will not operate in an area of concern with resonance.