MINOR LOSSES IN THE PIPE SYSTEM
Object
To determine minor losses due to a 45o elbow.
Apparatus
Fluid friction apparatus; hydraulic bench; and Stopwatch.
Fig. Fluid friction apparatus
Theory
The minor loss due to a 45o elbow is a function of velocity head and is written as
V 2
h K
l
e 45 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),
Ke 45
2g
V 2
.hl
2 981
(Q / 2.27)2
.hl
10108.2 hl
Q2
(2)
Procedure:
- Fill the tank of the hydraulic bench with clean water.
- Connect the fluid friction apparatus with the hydraulic bench.
- Open the valve(s) that allow flow to the section under consideration and close all the irrelevant valves of the pipe friction apparatus.
- Connect the two ends of the tubes to the pressure-tapping nipples at either side of the pair of elbows and manometer.
- Slightly open the flow control valve at 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 7 and 8 to observe new readings.
- Carry out computations as per the table below and compare the average value of Ke45 for a 45o elbow with that given in the literature, i.e., Ke45 = 0.2.
Observations and Calculations:
S. No. | Head (cm) | Discharge (cm3/sec) | K 10108.2 hl e 45Q2 | |||||
h1 | h2 | hl = h1 – h2 | V | V | T | Q = V/t | ||
(cm) | (cm) | (cm) | (lit) | (cm3) | (sec) | (cm3/sec) | ||
1 | ||||||||
2 | ||||||||
3 | ||||||||
4 | ||||||||
5 | ||||||||
Average Ke45 = | ||||||||
Comments:
