Blade bending moments are being measured on a research wind turbine on a day in which the wind speed at the hub height is 9.0 m/s. A wind shear results in a higher wind speed of 12.0 m/s at the top of the blade tip path and lower wind speeds of 6.0 m/s at the bottom of the blade tip path. A wind direction change results in a cross-wind of 0.60 m/s. The 24 m. diameter turbine starts with a flap hinge angle, β0 = 0.05 radians, and, at the moment that measurements are being made, the rate of change of the flap hinge angle is dβ1s/DT = 0.01 rad/s. The rotor has a fixed rotation rate of Ω = 0.159s−1 (or a frequency of 1 Hz.) and is 3.05 m/s from the yaw axis (bearing support). The blade pitch angle is θcp = 0.05 radians (2.86◦ ).

1. Describe how the blade angle of attack would vary during one complete rotor revolution.

2. List all of the effects these conditions have on the load on the bearing.

3. Estimate the load due to the yawing motion of the rotor.

Answer rating: 100% (QA)

1The blade angle of attack would vary during one complete rotor revolution due to the wind shear and ... View the full answer