Environmental Engineering Reference
In-Depth Information
M
yB
¼
0
:
4
2
:
99
2
0
:
218
0
:
379
þ
2
2
:
99
0
:
0633
73
:
30
þ
0
:
97
9
118
:
55
¼
40
:
83 Nm
ð
9
:
45
Þ
Similarly, (
9.12
) gives the shaft moment as
M
shaft
¼
3
2
:
99
73
:
30
0
:
0633
þ
3
:
98
9
:
81
0
:
0260
þ
0
:
97
6
118
:
55
¼
61
:
81 Nm
ð
9
:
46
Þ
In both (
9.45
) and (
9.46
), the gyroscopic terms are responsible for over two-
thirds of the moment.
9.4.3 Loads for Case C: Yaw Error
Eq. 9.13 for this load requires avalue for A
proj,B
. This can be done using a mod-
ification of the analysis in
Sect. 6.4
. For the three blades, A
proj,B
= 0.231 m
2
for
zero yaw. With C
l,max
= 2.0, Eq.
9.13
gives
"
#
2
M
y
;
B
¼
1
4
3
6
:
77
þ
1
6
:
77
8
1
:
2250
0
:
231
2
0
:
97
3
73
:
30
2
1
þ
¼
422
:
82 Nm
ð
9
:
47
Þ
9.4.4 Loads for Case D: Maximum Thrust
Using Eq.
9.14
the calculation is straightforward:
F
x
shaft
¼
3
:
125
0
:
5
1
:
225
7
:
5
2
p
0
:
97
2
¼
318
:
25 N
ð
9
:
48
Þ
9.4.5 Loads for Case E: Maximum Rotational Speed
The calculation of the centrifugal loading at the blade root is also straightforward.
From (
9.15
)
F
zB
¼
0
:
4
104
:
72
2
0
:
379
¼
1662
:
48 N
ð
9
:
49
Þ
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