MENG353-Exp2-18700815.docx - Eastern Mediterranean...

E astern M editerranean U niversity D epartment of M echanical
E ngineering L aboratory H andout
COURSE: Fluid Mechanics ( MENG353)
Semester: SPRING (2020-2021)
NAME OF EXPERIMENT: FLOW THROUGH A VVENTURI METER
Instructor: Assoc. Prof. Dr. Hasan Hacışevki
Assistant: Erfan Malekian
Submitted by: Sultan Elturkemany
Student No: 18700815
Group No: 01
Date of experiment: 19/05/2021
Date of submission: 31/05/2021
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EVALUATION
Activity During Experiment & Procedure 30
%
Data , Results & Graphs 35
%
Discussion, Conclusion & Answer to Questions 30
%
Neat and tidy report writing 5 %
Overall Mark
1

`
TABLE OF CONTENTS:
INTRODUCTION ........................................................................................................................... 3
DESCRIPTION OF APPARATUS .................................................................................................. 3
THEORY OF THE VENTURI METER ..................................................................................... 4
EXPERIMENTAL PROCEDURE ............................................................................................... 7
RESULTS AND CALCULATION ............................................................................................... 8
Discussion of Results .................................................................................................................... 12
CONCLUSION 14
2

1. INTRODUCTION :
The Venturi tube is a device that measures the flow rate in a pipe. With an increase in the
velocity in the throat, fluid moving through it accelerates in the direction of the tapering
contraction. A drop in pressure follows, the magnitude of which is determined by the rate of
flow. The difference in pressure measured by piezometers placed upstream at the throat can thus
be used to estimate the flow rate. The Venturi effect describes the influence of the meter on
pressure changes. A venturi can also be used to combine a gas and a liquid. If a pump forces
liquid through a tube connected to a system that includes a venturi to increase liquid speed (so
the diameter decreases), a short piece of tube with a small hole, and finally a venturi to decrease
speed (so the pipe gets wider again), the gas will be sucked in through the small hole due to
pressure changes. At the end of the system, a mixture of liquid and gas will appear.
2. DESCRIPTION OF APPARATUS:
Figure 1.1 shows the arrangement of the venturi meter, which is manufactured in clear
plastic material. Water is admitted from the bench supply valve and passes through a flexible
hose into the meter. Beyond the control valve, which is mounted just downstream of the meter a
further flexible hose leads to the measuring tank. The manometer tube, mounted in front of a
scale marked in millimeters. The manometer tubes are connected at their top ends to a common
manifold, in which the amount of air may be controlled by a small air valve at one end. The
whole assembly is supported on a base mounted on adjusting screws which serve to level the
equipment.
3

Fig 1.1 Arrangement of Venturi meter apparatus
3. THEORY OF THE VENTURI METER:
Consider flow of an incompressible, inviscid fluid through the convergent – divergent Venturi
tube shown in Fig 1.2. The cross sectional area at the upstream section 1 is
A
1
, at the throat
section 2 is
A
2
, and at any other arbitrary section n is
A
n
. Piezometer tubes at these sections
register
h
1
,
h
2
and
h
n
above the arbitrary datum shown. Note that, although the tube
may have any inclination, the datum must by necessity, be horizontal. Assume that both the
velocity and the piezometric head are constant over each of the sections considered. This amount
to assuming the flow to be one dimensional so that the velocity and the piezometric head vary
only in the direction of the tube length. We may then treat the convergent – divergent pip as a
stream tube along which Bernoulli theorem states.