sin αst

LIST OF ATTACHMENTSBASIS FOR CALCULATIONS
Load case B: Yawing
For this load case the ultimate loads during yawing are calculated for the blades and shaft.
The flapwise bending moment acting on the blades is considered to consist of three terms:
126
� Centrifugal force
� Gyroscopic
� Eccentricity of axial load
The first two terms occur due to the maximum yaw speed �yaw which is considered to oc-
cur with �design.
The last term accounts for an offset of the axial force, similar to that of (A.8).
For each blade the formula for the flapwise bending moment is:
(A.9)
(A.10)
The centrifugal force due to the yaw rate is multiplied by the distance Lrt of figure A.2. The
gyroscopic term is elaborated further in [5, p. 165].
For the shaft the bending moment is given by:
(A.11)
The load consists of a gyroscopic load valid for a three bladed rotor and two terms adding
mass loads and axial load eccentricity.
Load case C: Yaw error
� �
�yaw 3 0.01 � R 2
= � � 2 2.96 rad
=
s
2 R
MyB mB �yaw Lrt Rcog � 2�yaw IB �design 9 �F �
� xS � 98.6 N m
R
MS B�yaw �design IB � mr g Lrb 6 �F �
� xS � 179 N m
All turbines operate with a certain yaw error. In this load case, a yaw error of 30° is con-
sidered to induce a blade root bending moment. It is derived using approximations that
simplify a condition, where an extreme load is caused by the combination of the instanta-
neous wind and the yaw error, which is thought to place the entire blade at the angle of
attack for maximum lift. Further details may be found in [5, p. 169].
1
MyB 8 � Aproj.B Cl.maxR 3 � 2 4
�
�design �1
� �
� 3�design �
�
�
1
� design
2
� �
� �
� �
� 200 N m
(A.12)