210
6 Fans and Flow Control Devices
V =
Q
S
=
20
m
3
s
2.3 m 2 = 8.69
m
s
Therefore, the dynamic pressure is:
VP =
1
2
ρ a V
2
=
1
2
1.2
kg
m 3
8.69
m
s
2 = 45.31 Pa
FTP = FSP + VP = 1045.31 Pa
Then, the total power needed to move that air quantity (useful power supplied to
the fluid) is:
Pw u = FTP Q = 1045.31 Pa · 20
m
3
s
= 20906.2 W = 20.9 kW
Exercise 6.4 The static (SP) and dynamic (VP) pressures have been measured for
the fans in the figures, their values being those given in the tables.
Case 1: Booster system
5
1
2
3
4
Pressure
SP
VP
Point
1
0
0
2
−400
80
3
400
80
4
0
80
5
0
0
Case 2: Exhausting system
1
2
3
4
6 Fans and Flow Control Devices
V =
Q
S
=
20
m
3
s
2.3 m 2 = 8.69
m
s
Therefore, the dynamic pressure is:
VP =
1
2
ρ a V
2
=
1
2
1.2
kg
m 3
8.69
m
s
2 = 45.31 Pa
FTP = FSP + VP = 1045.31 Pa
Then, the total power needed to move that air quantity (useful power supplied to
the fluid) is:
Pw u = FTP Q = 1045.31 Pa · 20
m
3
s
= 20906.2 W = 20.9 kW
Exercise 6.4 The static (SP) and dynamic (VP) pressures have been measured for
the fans in the figures, their values being those given in the tables.
Case 1: Booster system
5
1
2
3
4
Pressure
SP
VP
Point
1
0
0
2
−400
80
3
400
80
4
0
80
5
0
0
Case 2: Exhausting system
1
2
3
4