home page for main menu
TRANSCRIPT
-
8/4/2019 HOME Page for Main Menu
1/13
HOMEpage for Main menu
Typical results using the equipment below.
Return to Lab Experiments page
For advice on how to write lab reports,click on this link
NOMENCLATURE
Units Nom. Type Description
Length of m L GivenLength of pipe test section. The
test pipe
Test Pipelength is measured in mm.
Convert to
metres for the calculation.
Diameter of m d Given Diameter of pipe test . The test
Test Pipepipe diameter is measured in
mm.
Convert to metres for the
calculation.
Volume m3 V MeasuredVolume of water collected in a
known
Collectedtime. The volume is measured in
ml.
Convert to cubic metres for the
calculation. (divide reading by
1,000,000)
Time to s t Measured Time taken to collect the known
Collect volume of water, V.
Temp of C MeasuredThe temperature of the water
collected.
http://www.jfccivilengineer.com/index.htmhttp://www.jfccivilengineer.com/index.htmhttp://www.jfccivilengineer.com/results_of_energy_loss.htmhttp://www.jfccivilengineer.com/results_of_energy_loss.htmhttp://www.jfccivilengineer.com/lab_experiments.htmhttp://www.jfccivilengineer.com/lab_experiments.htmhttp://www.jfccivilengineer.com/lab_reports.htmhttp://www.jfccivilengineer.com/lab_reports.htmhttp://www.jfccivilengineer.com/lab_reports.htmhttp://www.jfccivilengineer.com/lab_reports.htmhttp://www.jfccivilengineer.com/lab_experiments.htmhttp://www.jfccivilengineer.com/results_of_energy_loss.htmhttp://www.jfccivilengineer.com/index.htm -
8/4/2019 HOME Page for Main Menu
2/13
Water
Kinematic m2/s Measured See Table
Viscosity
Manometer m h1 Measured
Head at inlet to test section of
the pipe.The head is measured in mm.
Convert to
metres for the calculation.
Manometer m h2 MeasuredHead at outlet to test section of
the pipe.
The head is measured in mm.
Convert to
metres for the calculation.
Head Loss m h1 -h2 CalculatedHead loss over the test section of
the
pipe.
Flow Rate m3/s Qt Calculated Volume Collected
Time to Collect
Velocity mls v Calculated Fluid velocity through the pipe
Friction Factor f
Reynolds Number Re
EXPERIMENTAL PROCEDURE
http://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%202.JPGhttp://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%201.JPGhttp://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%202.JPGhttp://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%201.JPG -
8/4/2019 HOME Page for Main Menu
3/13
Objective
To investigate the head loss due to friction in the flow of water through a pipe
and to determine the associated friction factor. Both variables are to bedetermined over a range of flow rates and their characteristics identified for
both laminar and turbulent flows.
Method
By measurement of the pressure difference between two fixed points in a long
(length = many diameters) straight tube of circular cross-section for steady flows.
The range of flow rates will cover both laminar and turbulent flow regimes.
Equipment
In order to complete the demonstration we need a number of pieces of
equipment.
The F1-1O Hydraulics Bench which allows you to measure flow by timed
volume collection.
The F1-18 Pipe Friction Apparatus.
A stopwatch to allow you to determine the flow rate of water.
A thermometer.
A spirit level for setting up the equipment.
A measuring cylinder for measuring very low flow rates.
Technical Data
The following dimensions from the equipment are used in the appropriate
calculations. If required these values may be checked as part of the
experimental procedure and replaced with your own measurements.
Length of test pipe L = 0.500 m
Diameter of test pipe d = 0.003 m
Theory
A basic momentum analysis of fully developed flow in a straight tube of unifom
cross section shows that the pressure difference (Pl - P2) between two points in
the tube is due to the effects of viscosity (fluid friction). The head-loss h is
directly proportional to the pressure difference (loss) and is given by
-
8/4/2019 HOME Page for Main Menu
4/13
h = (Pl -P2)
g
and the friction factor, f, is related to the head-loss by the equation
h = 4fLv22gd
where d is the pipe diameter and, in this experiment, h is measured directly by
a manometer which connects to two pressure tappings a distance L apart; v is
the mean velocity given in terms of the volume flow rate Qt by
v = 4Qt
d2
The theoretical result for laminar flow is
f = 16
Re
where Re = Reynolds number and is given by
Re = vd
and is the kinematic viscosity.
Procedure - Equipment Set Up
Mount the test rig on the hydraulic bench and, with a spirit level, adjust the feet
to ensure that the base plate is horizontal and, hence, the manometers are
vertical.
Check with your tutor that the mercury (Hg) manometer is correctly filled;
this should not be attempted by students because Hg is a hazardous substance.
Attach a Hoffman clamp to each of the two manometer connecting tubes and
close them off.
http://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%205.JPG -
8/4/2019 HOME Page for Main Menu
5/13
Setting-up for high flow rates
The test rig outlet tube must be held by a clamp to ensure that the outflow point
is firmly fixed. This should be above the bench collection tank and should allow
enough space for insertion of the measuring cylinder.
Hoffman Clamp (white) Measuring Cylinder next to outlet pipe
Join the test rig inlet pipe to the hydraulic bench flow connector with the pump
turned off.
Close the bench gate-valve, open the test rig flow control valve fully and start
the pump.
Flow control valve (blue top)
Now open the gate valve, on the work bench, progressively and run the system
until all air is purged.
Open the Hoffman clamps and purge any air from the two bleed points at the
top of the Hg manometer.
Setting up for low flow rates (using the header tank)
Attach a Hoffman clamp to each of the two manometer connecting tubes and
close them off.
With the system fully purged of air, close the bench valve, stop the pump, close
the outflow valve and remove Hoffman clamps from the water manometer
connections.
http://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%203.JPGhttp://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%207.JPGhttp://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%206.JPGhttp://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%203.JPGhttp://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%207.JPGhttp://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%206.JPGhttp://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%203.JPGhttp://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%207.JPGhttp://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%206.JPG -
8/4/2019 HOME Page for Main Menu
6/13
Water manometer
Disconnect test section supply tube and hold high to keep it filled with liquid.
Connect the bench supply tube to the header tank inflow, run the pump and
open the bench valve to allow flow. When outflow occurs from the header tank
snap connector, attach the test section supply tube to it, ensuring no air is
entrapped.
When outflow occurs from header tank overflow, fully open the outflow control
valve.
Slowly open air vents at top of water manometer and allow air to enter until
manometer levels reach a convenient height, then close the air vent. If
required, further control of levels can be achieved by use of the hand-pump to
raise the manometer air pressure.
Procedure - Taking a Set of Results
Running high flow rate tests
Apply a Hoffman clamp to each of the water manometer connection tubes
(essential to prevent a flow path parallel to the test section).
Close the test rig flow control valve and take a zero flow reading from the Hg
manometer.
With the flow control valve fully open, measure the head loss h Hg shown by the
manometer.
Determine the flow rate by timed collection and measure the temperature of
the collected fluid.
The Kinematic Viscosity of Water at Atmospheric Pressure can then be
determined from the table provided further on this page.
Repeat this procedure to give at least nine flow rates; the lowest to give h Hg =
http://www.jfccivilengineer.com/images/energy%20losses%20in%20pipes%204.JPG -
8/4/2019 HOME Page for Main Menu
7/13
30mm Hg, approximately.
Running low flow rate tests
Repeat procedure given above but using water manometer throughout.
With the flow control valve fully open, measure the head loss h shown by the
manometer.
Determine the flow rate by timed collection and measure the temperature of
the collected fluid.
The Kinematic Viscosity of Water at Atmospheric Pressure can then be
determined from the table provided.
Obtain data for at least eight flow rates, the lowest to give h = 30mm,
approximately.
Plot graphs for log f against log Re and compare with the Moody diagram.
and
Plot log i against log v to determine the relationship between head loss and
velocity
This is what your results should look like
-
8/4/2019 HOME Page for Main Menu
8/13
-
8/4/2019 HOME Page for Main Menu
9/13
-
8/4/2019 HOME Page for Main Menu
10/13
-
8/4/2019 HOME Page for Main Menu
11/13
-
8/4/2019 HOME Page for Main Menu
12/13
Kinematic Viscosity of Water at Atmospheric Pressure
TemperatureKinematic
Viscosity
TemperatureKinematic
Viscosity
(degrees C) (x10-6 m2/s) (degrees C) (x10-6 m2/s)
0 1.793 25 0.893
1 1.732 26 0.873
2 1.674 27 0.854
3 1.619 28 0.836
4 1.568 29 0.818
5 1.520 30 0.802
6 1.474 31 0.785
7 1.429 32 0.769
8 1.386 33 0.753
9 1.346 34 0.738
10 1.307 35 0.724
11 1.270 36 0.711
12 1.235 37 0.697
13 1.201 38 0.684
14 1.169 39 0.671
15 1.138 40 0.658
16 1.108 45 0.602
17 1.080 50 0.554
18 1.053 55 0.511
19 1.027 60 0.476
20 1.002 65 0.443
21 0.978 70 0.413
-
8/4/2019 HOME Page for Main Menu
13/13
22 0.955 75 0.386
23 0.933 80 0.363
24 0.911 85 0.342
Eg. At 20C the kinematic viscosity of water is 1.002 x 10-6m2/s.
Return to Lab Experiments page
http://www.jfccivilengineer.com/lab_experiments.htmhttp://www.jfccivilengineer.com/lab_experiments.htmhttp://www.jfccivilengineer.com/lab_experiments.htm