Experiment # 05
MINOR LOSSES IN THE PIPE SYSTEM
Object: To determine minor losses due to a 45o elbow.
Apparatus: Fluid friction apparatus; Hydraulics bench and Stop watch.
Fig. Fluid friction apparatus
Theory: The minor loss due to a 45o elbow is a function of velocity head and is written as
V2
hl K e 45 (1)
2g
where
hl = loss of head due to Elbow
V = velocity of flow = Q/A
3.14
where, Area of flow = A d2 (1.7) 2 2.27 cm 2
4 4
(since d = 17 mm = 1.7 cm)
2g 2 981 h
Putting values in Eq.(1), K e 45 2
.hl 2
.hl 10108.2 l2 (2)
V (Q / 2.27) Q
Procedure:
1. Fill tank of hydraulics bench with clean water.
2. Connect the fluid friction apparatus with hydraulics bench.
3. Open the valve(s) that allows flow to the section under consideration and close all the
irrelevant valves of the pipe friction apparatus.
4. Connect the two ends of the tubes to the pressure tapping nipples at the either side of
the pair of the elbows and the manometer.
5. Slightly open the Flow control valve at the hydraulics bench.
6. Remove air bubbles from the tubes by opening the Vent valve and Drain valves of
differential manometer.
7. Read the heads in the monometers corresponding to the pressure along entry and exit
of the elbows.
8. Collect water in the volumetric measuring section of the hydraulics bench. Read the
volume collected as well as time taken to collect that volume of water.
9. Open the Flow control valve at the hydraulics bench slightly more for taking new
reading.
10. Repeat steps 7 and 8 to observe new readings.
11. Carry out computations as per table below and compare the average value of Ke45 for
a 45o elbow with that given in literature i.e. Ke45 = 0.2.
Observations and Calculations:
Head (cm) Discharge (cm3/sec) K e 45 10108.2
hl
S. Q2
No. hl Q
h1 h2 V V T
= h1 – h2 = V/t
(cm) (cm) (cm) (lit) (cm3) (sec) (cm3/sec)
1
2
3
4
5
Average Ke45 =
Comments:
Sig. of Lab. Lecturer: ________________________ Date: _________
Experiment No. 6
CORRELATION BETWEEN TYPES OF FLOW AND REYNOLD’S NUMBER
Object:
To establish correlation between types of flow and R
Apparatus:
1. Reynold’s Number Experimental Apparatus (Model RNM-15-900), consisting of:
Perspex water tank
Baffle for flow stilling
Perspex flow tube
Dye pot
Dye injector nozzle
Rotameter
2. Thermometer
Fig. 28.1 Reynold’s Number Experimental Apparatus (Model RNM-15-900)
(a) Laminar Flow (b) Turbulent Flow
Fig. 8.2. Flow visualization:
Theory:
In pipe flow:
Vd
R
v Type of flow
2300 Laminar or Streamline
> 2300 Turbulent
Procedure:
(1) Open city water supply cock and let the water flow calmly into the water tank without
cresting the surface of water, and attain a steady level.
(2) Let the water flow out of the tank through the transparent flow view tube.
(3) Open dye injector nozzle and let the dye flow through flow view tube and observe the
type of flow. Also read discharge Q from the rotameter.
(4) Increase Q in increments; observe type of flow each time as well as note the rotameter
reading.
(5) Measure temperature of water.
Observations & Calculations:
Table 8.1
KINEMATIC VISCOSITY OF WATER
T Kinematic Viscosity (v)
o -3
( C) (cm2/s x 10 )
0 17.94
5 15.35
10 12.97
15 11.37
20 9.96
25 8.84
30 7.96
35 7.24
40 6.63
45 6.11
50 5.62
55 5.18
60 4.80
Table 8.2
d (tube dia) = 1.5 cm
R Are the
Q Magnitude
Q Visual magnitude
S. Q x 1000 of R is <,
Qr T V observation and visual
No. r π = or > 2300
3600 dv of flow type observation in
4 ?
conformity?
0
lit./h cc/s C cm2/s
Comments:
Sign. of Lab. Lecturer: _____________________ Date: ___________________
Experiment No. 7
PIPE BEND CONNCETION
Object: Comparison of pipe bend section of fluid friction and losses in pipes and bends
apparatus.
Apparatus: Losses in bends and fittings apparatus, Fluid friction apparatus, hydraulics bench and
stopwatch.
Theory: The minor loss due to a pipe bend is a function of velocity head and is written as
V2
hl K b (1)
2g
where
hl = loss of head due to pipe bend
V = velocity of flow = Q/A
3.14
where, Area of flow = A d2 (1.7) 2 2.27 cm 2
4 4
(since d = 17 mm = 1.7 cm)
2g 2 981 h
Putting values in Eq.(1), Kb 2
.hl 2
.hl 10108.2 l2 (2)
V (Q / 2.27) Q
But the loss coefficient in case of pipe bend is a function of bend radius (r) and inside diameter
of the bend (d) as shown below
In the Fluid friction apparatus, r = 3.0 cm and d = 1.7 cm, i.e. r/d = 1.76, hence Kb = 0.2.
Observations and Calculations: (Using Fluid friction apparatus)
Table
S. Head (cm) Discharge (cm3/sec) K b 10108.2
hl
No. Q2
h1 h2 hl = h1 – h2 V T Q = V/t
3
(cm) (cm) (cm) (lit) (cm ) (sec) (cm3/sec)
1
2
3
4
5
Average Kb =
Observations and Calculations: (Using Losses in pipe & bend apparatus)
Table
S. Head (cm) Discharge (cm3/sec) K b 10108.2
hl
No. Q2
h1 h2 hl = h1 – h2 V T Q = V/t
(cm) (cm) (cm) (lit) (cm3) (sec) (cm3/sec)
1
2
3
4
5
Average Kb =
Comments:
Sig. of Lab. Lecturer: ________________________ Date: __________
