Environmental Engineering Reference
In-Depth Information
Table 11-5.
Characteristics of the Baseline 1.5 MW WindPACT Blade and Rotor
Characteristic
Units
Value
Rated power
MW
1.5
Rotor diameter
m
70
Max rotor speed
rpm
20.5 (0.342 Hz)
Max tip speed
m/s
75
Blade coning
deg
0
Max blade chord
m
8% of radius
Radius to blade root
m
5% of radius
Rotor solidity
0.05
Blade mass
kg
4,230
Hub mass
kg
15,104
Total rotor mass
kg
32,016
1
st
flapwise frequency
Hz
1.233 (1.199)
1
st
edgewise frequency
Hz
1.861 (1.714)
2
nd
flapwise frequency
Hz
3.650 (3.596)
1
st
torsional frequency
Hz
9.289 (9.846)
Although not readily apparent from Figure 11-16, the blade has a modest amount of
twist, from 11.1 deg. at the root to 0.0 deg. at the tip. The modal frequencies in parentheses
in this table were computed with the software developed herein with W set to zero and the
Theodorsen function,
C(k)
, set to 1.0. They differ from the companion frequencies taken
from the WindPACT study, which were computed using the ADAMS software (developed
by the MSC Software Corp.). The two models are inherently different, yet the frequency dif-
ferences are small. Only minimal effort was made to minimize these differences.
In Figure 11-17 a planform view of the blade is presented showing the positions of the
elastic axis and the axis representing the locus of the cross-sectional center of gravity. As
the elastic axis is forward of the mid-chord, the quantity
a
in Equations (11-59) is negative,
varying along the span from - 0.354 to - 0.284. Since in this implementation a constant value
of
a
is required, a mid value of - 0.32 was selected.
1
1
1
Leading edge
Leading edge
Elastic axis
Elastic axis
0
0
0
Center of gr avity
Center of gr avity
-1
-1
-1
Mid-chord
Mid-chord
Trailing edge
Trailing edge
-2
-2
-2
0
0
5
5
10
10
15
15
20
20
25
25
30
30
35
35
Distance from rotor center (m)
Distance from rotor center (m)
Figure 11-17. Diagram of the planform of the baseline 1.5 MW WindPACT blade show-
ing the locations of the elastic axis and the cross-sectional centers of gravity.
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