216
6 Fans and Flow Control Devices
(c) The absorbed intensity can be obtained from:
I =
Pw
√
3 U cos Φ
=
3720.93 W
√
3 · 6000 V · 0.85
= 0.447 A
(d) The lost power (Pw L ) is, therefore:
Pw L = Pw−Pw shaft = 3720.93 W − 3200 W = 520.93 W
6.2.8 Affinity Laws in Fans
For these laws to be applied, it is required that the two fans are dynamically
similar, which means that both are constructed geometrically similar and the velocity
diagrams in their homologous points are also similar.
Rotation Speed Variation
In the case of a fan, whose speed varies from N 0 to N (Fig. 6.10), Eqs. 6.13, 6.14
and 6.15 are applicable (Fig. 6.16).
Flow rate (Q):
Q = Q 0
N
N 0
(6.13)
Pressure (P):
P = P 0
N
N 0
2
(6.14)
Fig. 6.16 Diagram of a fan rotating at a speed N 0 and N > N 0
6 Fans and Flow Control Devices
(c) The absorbed intensity can be obtained from:
I =
Pw
√
3 U cos Φ
=
3720.93 W
√
3 · 6000 V · 0.85
= 0.447 A
(d) The lost power (Pw L ) is, therefore:
Pw L = Pw−Pw shaft = 3720.93 W − 3200 W = 520.93 W
6.2.8 Affinity Laws in Fans
For these laws to be applied, it is required that the two fans are dynamically
similar, which means that both are constructed geometrically similar and the velocity
diagrams in their homologous points are also similar.
Rotation Speed Variation
In the case of a fan, whose speed varies from N 0 to N (Fig. 6.10), Eqs. 6.13, 6.14
and 6.15 are applicable (Fig. 6.16).
Flow rate (Q):
Q = Q 0
N
N 0
(6.13)
Pressure (P):
P = P 0
N
N 0
2
(6.14)
Fig. 6.16 Diagram of a fan rotating at a speed N 0 and N > N 0