Environmental Engineering Reference
In-Depth Information
Fig. 2.6
Curves of power coefficient
c
p
(λ ) and torque coeffient
c
T
(λ ) of a three-blade rotor
defined which allows to calculate the axial drag force, see Fig. 2.7. With rigid blade
this coefficient is small for low
λ
, and attains at no-load speed (large
λ
) values
similar to a circular plane subjected to air flow in normal direction.
Torque
T
,power
P
and axial drag force
S
may be expressed by a set of equations
using the reference force
F
B
which varies with the square of the wind speed and is
proportional to the swept rotor area:
D
2
F
B
=
2
π
v
1
4
(2.8)
)
D
T
=
c
T
(
λ
2
·
F
B
;
P
=
c
P
(
λ
)
·
v
1
·
F
B
;
S
=
c
S
(
λ
)
·
F
B
Fig. 2.7
Curve of drag (drag) coefficient
c
S
(
λ
)
Search WWH ::
Custom Search