Lab 4 Fluid Friction in Pipes

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EXPERIMENT: Lab 4 Fluid friction in pipes
DATE

Objectives
 Determine relationship between the head loss and fluid velocity.
 Express the relationship that exists between the head loss and flow velocity.
 Make a comparison between the calculated and the measured and head losses.
 To determine pipe roughness.
Introduction
The main purpose of this experiment’s was to investigate relationship between the head losses
and the velocity of flow. Head losses are caused by fluid friction. It was done with respect to
both a smooth and rough test pipes. This was achieved after establishing the relationship that
existed between the head loss and flow velocity. Relationship was used in comparing the
measured head loss and calculated head loss. The unknown pipe roughness was also established.
Theory
A fluid experiences some resistance when flowing through a pipe. This is due to the shear
stresses that convert fraction of the fluid’s energy into a loss and it is known as head loss which
is a product of friction and it is a function of the pipe’s length, diameter, mean flow velocity,
fluid’s property and actual pipe roughness. An important note is that head loss as a result of
friction is independent of the fluid flow pressure, in this case water [1].
Mathematical expression of the relationship between head loss and flow velocity:
hL=f L
D
V 2
2 g
Where:
hL=head loss due ¿ friction( m)
f =friction

L=length of pipe(m)
D=diameter of pipe(m)
V =average flow velocity (ms−1 )
g=acceleration due ¿ gravity (ms−2 )
Measurement and determination of the pipes head losses can be done by considering a given
range of Reynolds’ number. These numbers are what determine if a pipe flow is laminar,
transitional or turbulent. A smooth pipe and a roughened test pipe are used.
Relationship between head loss and flow velocity [2]:
hL ≈ V for laminar flow
hL ≈ for turbulent flow
In transitional flow, it is challenging to determine the effects of fluid friction that can cause head
losses and establish its relationship with the flow velocity.
Apparatus
 Fluid friction apparatus.
 Hydraulic Bench.
 Portable pressure meter.
 Volumetric tank.
 Measuring cylinder.
 Vernier Calipers.
Procedure

 Priming of the pipe network was done until air appeared not to be discharged from the
apparatus.
 Valves were opened and closed and water flow was obtained through the required test
pipe where four lowest pipes of fluid friction apparatus were used.
 Head losses between the tappings were measured by portable pressure meter for five
different flow rates achieved by altering the flow on the control valve of the hydraulics
bench of each pipe.
 The internal diameter of individual test pipe was then measured using a Vernier caliper.
 The results were recorded in a tabular form.
Data
Smooth Pipe 1 Smooth Pipe 2 Smooth Pipe 3 Rough Pipe
Diameter (m) 0.00749 0.01059 0.01684 0.01684
Smooth Pipe 1
Run Measuring Tank
Volume
Measuring Time
(s)
Head Loss (m)
(max/min)
1 0.002 15.45 15.44 15.43 11.31 10.47
2 0.002 9.40 9.40 9.40 32.16 31.21
3 0.005 14.40 14.40 14.40 73.44 71.08
4 0.005 13.24 13.24 13.24 77.25 74.62
5 0.005 10.60 10.60 10.60 79.60 76.82
Smooth Pipe 2
Run Measuring Tank Measuring Time Head Loss (m)