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Fluid machines
UiTMSarawak/ FCE/ BCBidaun/ ECW301
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Introduction
Fluid machines
Pumps
Mechanical energy 
fluid energy
Turbines
Fluid energy 
mechanical energy
(electrical energy)
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Pumps
Adds energy to the system by increasing the
velocity or the pressure, or both.
Positive
displacement
Rotary
Rotodynamic
Reciprocating
Centrifugal
Mixed flow
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Axial flow
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Energy equation
2
2
p1 v1
p2 v2

 z1  hp  h 

 z2
g 2 g
g 2 g
• Where hp = head gain from the pump
h = head loss in the pipe from
friction & separation losses
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Centrifugal pump
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Characteristics curves
• Characteristic curves
– Head vs discharge
– Efficiency vs discharge
• Show the characteristic
of a particular pump
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• Theoretically H vs Q gives a straight line.
• Actual H is less than theoretical – head loss in pump.
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• Complete set of
characteristic curves:
– H vs Q
– η vs Q
– P vs Q
• H, actual head:
theoretical head minus
loss in pump.
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Power,P  gQH
Pout gQH
Efficiency,  

Pin
P
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Pumping between reservoirs
hd
hs
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•
•
•
•
s – suction side
d – delivery side
Pump increases the head in pipe by zb – za.
Breaking down the head into suction head hs &
delivery head hd,
zb  za  hs  hd
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• Writing energy equation between reservoirs,
2
2
pa va
pb vb

 za  hp  h 

 zb
g 2 g
g 2 g
• Simplifying & rearranging,
hp  zb  za  h
• Subtituting,
hp  hs  hd  h
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Example 5.1
• It is required to pump water at a rate of 50 L/s
from one reservoir to another reservoir which has
an elevation 20 m higher. A centrifugal pump is
located 7.5 m above the lower reservoir. The pipe
connecting the reservoirs has a 150 mm diameter.
The length from the lower reservoir to the pump
is 100 m while the length from the pump to the
higher reservoir is 200 m. Assuming the friction
factor is 0.01 and separation losses are neglected,
what is the head need by the pump?
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Pumps in piping system
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Pumps combined in parallel
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Pumps combined in series
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Example 5.2
• A centrifugal pump has the characteristics shown
in table below. It is used to lift between two
reservoirs with a difference of elevation of 5.0 m
as shown in figure. The pipe connecting the
reservoirs has a diameter of 150 mm and is 800 m
long. The friction factor is assumed to be 0.01.
The pipeline includes four standard elbows and
three gate valves. The entrance and exit are sharp.
a) Plot the characteristic curves including the system
curve.
b) Determine the rate of flow delivered by the pump.
c) What is the power required?
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Q (L/s)
0
5
10
15
20
25
H (m)
22
20
16.7
12.5
7.6
2
η (%)
0
44
60
63
53
1
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Problem 5.1
• A pump is used to deliver water from a
reservoir at an elevation 10 m to another at an
elevation of 35 m. The water is delivered at
rate of 50 L/s through a suction pipe 25 m long
and 200 mm diameter. The delivery pipe is 150
m long and 150 mm diameter. If the friction
factor f is assumed to be 0.005, determine the
head produced by the pump. The pump is
located at an elevation of 14.5 m.
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Problem 5.5
• A centrifugal pump has the following
characteristics as in table shown. It is used to lift
water between two reservoirs with a difference of
elevation of 5.0 m as shown in figure. The pipe
connecting the reservoirs has a diameter of 150
mm and is 400 m long. The friction factor is
assumed to be 0.01.
a) Plot the characteristic curves.
b) Determine the rate of flow delivered by the pump.
c) What is the power required by the pump?
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Q (L/s)
0
5
10
15
20
25
H (m)
19.8
18
15
11.3
6.8
1.8
η (%)
0
35.2
48
50.4
42.4
0.8
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Apr 2010 Q5(b)
• Two pipes are connected in series and is used to
connect two reservoirs as shown in figure. Both pipes
are 500 m long and have diameters of 0.7 m and 0.5 m
respectively. The discharge from reservoir A is 85 m.
Using the appropriate equations and assuming sharp
exit and entry as well as existence of sudden
contraction at the junction, determine:
i. Velocity for each pipe.
ii. Head losses due to friction, separation and fittings.
iii. Elevation of water surface in reservoir B
(CC = 0.674, μ = 1.14 x Ns/m2 and k = 0.15 mm)
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