EXPERIMENT
VENTURI
METER
1. Objective:
To study the flow
measurement using a venturimeter. Also to determine the coefficient of
discharge through the venturimeter.
2. Introduction:
A venturimeter is a
device which is used for measuring the rate of flow of a fluid flowing through
a pipe. Venturimeter mainly consist of three main parts -the converging
section, diverging section and the throat. As the fluid moves through the pipe,
it accelerates in the direction of the tapering contraction with an increase in
the velocity in the throat. This leads to fall in pressure, the magnitude of
which depends on the rate of flow. The flow rate is calculated from the
difference in pressure using the manometers placed upstream at the throat. The
effect that the meter has on the pressure change is termed as the Venturimeter
effect
3. Procedure
i.
Make sure all the valves are closed and
the measuring tank is clean and empty.
ii.
Note the pipe diameter (d1) and throat diameter
(d2) of Venturimeter. Note the density of manometric liquid i.e. mercury and
that of fluid flowing through pipeline i.e. water.
iii.
Now the main power is to be switched on so
that the water starts flowing followed by the pump.
iv.
Particular care should be taken to clear
all air from the manometer connections. This can be done by adjusting the tubes
attached to the manometer. Now Open the control valve completely and using the
diverter fill up the measuring tank for 15 seconds.
v.
The height must be noted down then using
the measuring scale up-to which the measuring tank must have been filled. This
is done for the flowrate calculations.
vi.
Calibrate the scale attached to the
measuring tank. The position of the control valve is changed and same procedure
is repeated. Thus there are three cases.
vii.
Simultaneously note down the manometer
readings and the height upto which measuring tank has been filled. Empty the
measuring tank and switch off the pump. Then empty the drainage tank and switch
off the main power.
4. Analysis
1) Diameter of pipe (D1) = cm
2) Area of pipe = cm^2
3) Calculated throat Diameter (D2)
= cm
4) Area of throat diameter
(Calculated) = cm^2
5) Actual throat Diameter (D2)
= cm
6) Area of Actual throat diameter
= cm^2
5. Result and Discussions
When throat diameter 1.33(cm)
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When throat diameter 1.4 (cm)
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Reynold number (Nre 1)
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fully open
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Partially open
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Almost closed
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Reynold number (Nre 2)
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fully open
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Partially open
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Almost closed
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Cd
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fully open
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Partially open
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Almost closed
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