MINOR LOSSES IN THE PIPE SYSTEM
Object
To determine minor losses due to a sharp 900 pipe elbow.
Apparatus
losses in bends and fittings apparatus; hydraulic bench and stopwatch.
Fig. Losses in bends and fittings apparatus
Theory
The minor loss due to a sharp 90o elbow is a function of velocity head and is written as
V 2
h K
l
e90 2g
(1)
where
hl = loss of head due to Elbow
V = velocity of flow = Q/A where,Area of flow =
A d 2
4
3.14
4
(1.7)2
2.27
cm2
(since d = 17 mm = 1.7 cm)
Putting values in Eq. (1),
2𝑔
Ke90 = 𝑣2 . ℎ𝑙
2 x 981. ℎ𝑙 = 10110
( 𝘘 )2
=
2.27
ℎ𝑙
𝑄2(2)
Procedure
- Fill the tank of the hydraulic bench with clean water.
- Connect the Losses in Bends and Fittings Apparatus with the hydraulic bench.
- Connect the two ends of the tubes to the pressure-tapping nipples at either side of the pair of elbows and the manometer.
- Slightly open the flow control valve on the hydraulic bench.
- Remove air bubbles from the tubes by opening the vent valve and drain valves of the differential manometer.
- Read the heads in the monometers corresponding to the pressure along the entry and exit of the elbows.
- Collect water in the volumetric measuring section of the hydraulic bench. Read the volume collected as well as the time taken to collect that volume of water.
- Open the flow control valve at the hydraulic bench slightly more to take new readings.
- Repeat steps 6 and 7 to observe new readings.
- Carry out computations as per the table below and compare the average value of Ke90 for a sharp 90o elbows with that given in the literature, i.e. Ke90 = 1.1
Observations and Calculations:
Table
S. No. | Head (cm) | Discharge (cm3/sec) | Ke90=10110 . ℎ𝑙 𝑄2 | |||||
h1 | h2 | hl = h1 – h2 |
|
| t | Q = V/t | ||
(cm) | (cm) | (cm) | (lit) | (cm3) | (sec) | (cm3/sec) | ||
1 | ||||||||
2 | ||||||||
3 | ||||||||
4 | ||||||||
5 | ||||||||
Average Ke90 = | ||||||||
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