CHEMICAL ENGINEERING LABORATORY
CHE331
TITLE : OSBORNE REYNOLD
GROUP : A6
POSITION NAME ID. NUMBER
PLANNER ORLANDO JIMLI PERIJIN 2011331035
EXPERIMENTER
MUHAMMAD SYAKIRAN IKHWAN BIN ZAKARIA
2011955115
ANALYZER NURUL SYAHEERAH BINTI CHE HASNAN
2011768091
CONSULTANT NURUL SUHAILA BINTI JAMAL 2011546471
CHEMICAL ENGINEERING LABORATORY REPORT EVALUATION SHEET 1
Group 6
Experiment: OSBORNE REYNOLD
PLANNER : ORLANDO JIMLI PERIJIN
SCOPE CRITERIAFULL
MARKS MARKS
INTRODUCTION General overview about the experiment 5
Aims/objectives Based on experiment in paragraph form 5
Theory Brief summary from the theory given; add additional data from resources
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Total:
Checked by:
EXPERIMENTER: MUHAMMAD SYAKIRAN IKHWAN BIN ZAKARIA
SCOPE CRITERIAFULL
MARKS MARKS
Diagram and description of apparatus
Include the description of main apparatus, as well as sketched diagram
5
Methodology/procedure
Simplified procedures based on what we have been done in lab
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Reference/appendix -extra information extracted/gathered from books/journal -complete raw data and appendices
5
Total:
Checked by:
2
ANALYZER: NURUL SYAHEERAH BT CHE HASNAN
SCOPE CRITERIA FULL MARKS
MARKS
RESULT -data must be similar with what was obtained during experiment -produce graph/figures based on the data obtained
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discussion Discuss what the result and data mean; discuss and relate the result obtained with the theory
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Total:
Checked by:
CONSULTANT: NURUL SUHAILA BT JAMAL
SCOPE CRITERIA FULL MARKS
MARKS
Abstract Must provide the objective of the experiment, procedure, result and conclusion.
5
Sample calculation - Sample of calculation of each variable- Present data accordingly
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conclusion Relate the result obtained with the objective of the experiment
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Recommendation -any improvement to be suggested by observing the inconsistencies observed in result/conclusion
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Total:
Checked by:
Abstract
3
In this experiment, Reynolds’s number for the flows laminar, transitional and
turbulent was compared. There were 2 total experiments involved. The objective for
experiment 1 was to compute Reynolds number (R) and to observe laminar, transitional,
and turbulent flow. Experiment 2 had an objective of determining the Reynolds’s number
(R) and determining the upper and lower velocities at transitional flow. Several steps
were taken to conduct the experiment. Firstly, the dye injector was lowered until it can
be seen in the glass tube. Inlet valve, V1, was then opened to allow water to enter the
stilling tank. Small overflow spillage was maintained at a constant level. Water was
allowed to settle for a few minutes. Water was left to flow into the visualisation tube. Dye
control valve, V4, was slowly adjusted until a slow flow with dye injection is achieved.
Water inlet valve, V1, and outlet valve, V2, were regulated until a straight (laminar)
identifiable dye line is achieved. The flow rate at the outlet valve, V2, was measured
using volumetric method. 4 litters of water for each flow was collected and replicated 3
times. The experiment was repeated in the same manner but regulate V1 and V2 to
produce transitional and turbulent flow. For the second experiment, procedures are
almost the same as experiment one with just a slight difference. First the dye injector
was lowered until seen in glass tube. Then inlet valve, V1, was opened to let water flow
into the tank. Small overflow spillage was ensured. Water was the allowed to settle for a
few minutes. Dye control valve, V4, was slowly adjusted until a slow flow with dye
injection is achieved. V1 and V2 were regulated to get laminar flow and slowly increase
the flow rate until the flow produced small disturbance. This was taken as the lower
critical velocity. The flow rate at the outlet valve, V2, was measured using volumetric
result. The experiment was repeated by introducing a turbulent flow and slowly decrease
the flow rate until the flow becomes transitional. This result is taken as the higher critical 4
velocity. The result of Reynolds number obtained from the experiment 1 were 397.56,
940.2, and 4060.54 respectively. The Reynolds numbers mostly follow theoretical
values except for transitional value which was caused by a few factors. As for
experiment 2, the lower and upper critical velocities obtained through calculations were
0.031m/s and 0.0766m/s respectively which produced Reynolds number if 535.84 at
lower critical velocity and 1324.1 at upper critical velocity.
Table of contents
Abstract........................................................................................................................1
Table of contents..........................................................................................................2
1.0 Introduction………………………………………………………………………...…….3
2.0 Objective……………………………………………………………………………...…..3
3.0 Theory………………………………………………………………………………...…..4
4.0 Diagram and Description of Apparatus……………………………………………......5
5.0 Experimental Procedures………………………………………………………………..6
6.0 Results and Discussion…………………………………………………………...……..8
7.0 Sample Calculations…………………………………………………………….………14 5
8.0 Conclusion and Recommendation……………………….………………………….…15
9.0 References.………………………………………………………………………..……..16
Introduction
Osborne Reynolds, one of the giants of the science world, dedicated his life to the
study of fluid dynamics. This experiment is one of his famous experiments dedicated to
studying the characteristics of laminar, transition, and turbulent flow in a pipe. The origin
of the infamous Reynolds number was created during his tinkering with water flow.
The Reynolds experiment setup consists of a water tank filled with rocks to
reduce water flow speeds into the glass tube, a dye reservoir to fill with dye, four valves
to control the dye, input, output, and overflow, a pump, and a water supply connection.
The laminar, turbulent and transitional flows can be obtained by altering the inlet and
outlet valves which also will give the optimal conditions for desired types of flow if
correctly used. The flows and the dye pattern which is injected from a dye injector can
be observed through the long glass tube and can be controlled by the dye valve. The
time taken to fill a desired volume with a flow type will help determine the Reynolds
number.
Objective
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o To compute the Reynolds number of flow.
o Observe laminar, transitional, and turbulent flow
o Determine the upper and lower critical velocities at transitional flow.
Theory
The Reynolds number is widely used dimensionless parameter in fluid
mechanics.
R=ULV
Where R is the Reynolds number, U is the Fluid velocity in unit meter per second, L is
the characteristic length or diameter in unit meters, and V is kinematic viscosity in unit
meter square per second. The Reynolds number, R, is independent of pressure.
Pipe Flow conditions:
For a pipe, L is the diameter which is different from a flat surface where L is the
length. When the Reynolds number is less than 2100, the pipe flow will be laminar. If the
Reynolds number is between 2100 to 4000, water flow in the pipe is said to be a
transitional flow. A Reynolds number of more than 4000 can be taken as a turbulent flow
in the pipe. The viscosity of the fluid also affects the characteristic of the flow whether it 7
will become laminar or turbulent. A fluid with lower viscosity will make it easier to
achieve a turbulent flow as proven by the Reynolds formula. The viscosity dependent on
the temperature.
Laminar flow
A steady flow condition where all streamlines follows parallel paths and there is
no mixing between shear planes. When a dye is subjected to this condition, it will appear
as a solid, straight, and easily identifiable component of flow.
Transitional flow
A flow between the characteristics of laminar and turbulent flow. Turbulence will
form in the middle of the pipe and laminar usually around the edges. Each of these flows
behaves differently in terms of their frictional energy loss while flowing, and have
different equations that predict their behaviour.
Turbulent flow
A flow that is unsteady and the streamlines mix which causes shear plane
collapse. Dye stream in the glass tube will disperse and mix and the stream will not be
identifiable at this point.
Diagram and Description of apparatus
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Unit assembly of Osborne Reynolds’s demonstration
1. Dye reservoir
2. Dye control valve
3. Dye injector
4. Bell mouth
5. Observation tube
6. Overflow valve, V3
7. Water outlet valve, V2
8. Water inlet valve, V1
9. Head tank
The Osborne Reynolds’s demonstration apparatus is equipped with a visualization
tank for students to observe the flow condition. The rocks inside the stilling tank are
to calm the inflow water so that there will not be any turbulence to interfere with the
experiment. The water inlet/outlet valve and dye injector are utilized to generate the
required flow.
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Experimental procedures
Experiment 1
1. Dye injector was lowered until can be seen in glass tube.
2. Inlet valve, V1, was opened to allow water to enter the spilling tank.
3. A small overflow spillage was ensured through the over flow tube to maintain a
constant level water.
4. Water was allowed to settle for a few minutes.
5. Water was allowed to flow through the visualizing tube.
6. Dye control valve, V4, was adjusted slowly until a slow flow with dye injection is
achieved.
7. V1 and V2 valve were regulated until a straight identifiable dye line was achieved.
The flow was a laminar flow.
8. Flow rate at outlet valve, V2, was measured using volumetric method. 4 litres for
each flow was taken and repeated over 3 times.
9. Experiment was repeated by regulating water inlet valve,V1, and outlet valve, V2
to produce transitional and turbulent flow.
Experiment 2
1. Dye injector was lowered until can be seen in glass tube.
2. Inlet valve, V1, was opened to allow water to enter the spilling tank.
3. A small overflow spillage was ensured through the over flow tube to maintain a
constant level water.
4. Water was allowed to settle for a few minutes.
Water was allowed to flow through the visualizing tube of fluid is
5. .
6. Dye control valve, V4, was adjusted slowly until a slow flow with dye injection is
achieved.
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7. Water inlet valve, V1, and water outlet valve, V2, was regulated to produce
laminar flow. Slowly the water flow rate was increased until the laminar flow
produced small disturbance.
8. Flow rate at outlet valve, V2, was measured using volumetric result.
9. Water inlet valve, V1, and water outlet valve, V2, was regulated to produce
turbulent flow. Slowly the water flow rate was decreased until transitional flow is
achieved. This was taken as the upper critical velocity.
Data sheet
Reynolds number Re (non-dimensional)
Friction Factor λ (non-dimensional)
Kinematics viscosity v mm²/s
Pipe diameter D mm
Mean velocity U mm/s
Higher critical velocity U crit mm/s
Lower critical velocity U crit mm/s
Flow rate Q L/s
Result
Laminar flow
Run number Volume (L) Time (s)
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1 4 904
2 4 892
3 4 898
Average 898
Transitional flow
Run number Volume(L) Time(s)
1 4 405
2 4 356
3 4 387
Average 382.7
Turbulent flow
Run number Volume(L) Time(s)
1 4 84
2 4 98
3 4 85
Average 89
Lower critical velocity
Run number Volume(L) Time(s)
1 4 676
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2 4 695
3 4 657
Average 676
Upper critical velocity
Run number Volume(L) Time(s)
1 4 277
2 4 271
3 4 271
Average 273
Result calculations
Laminar flow rate
Average time = 904+892+898 = 898 s
3
Flow rate (m³/s) = 4 L = (4.45 × 10 ^ -3 L/s) × (0.001m³)= 4.45 × 10^ -6
898 s 1 L m³/s
Velocity (m/s) = 4.45 × 10^ -6m³/s= 0.023 m/s
[Π (0.0156)² m² / 4]
Re = 0.023 (m/s) × 0.0156 m= 397.56 0.9025 ×10 ^ -6 (m²/s)
Transition flow
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Average of time(s) = 405+356+387 = 382.7 s 3
Flow rate (m³/s) = 4 L = (0.0104 L/s) × (0.001m³)= 1.04 × 10^ -5
382.7 s 1 L m³/s
Velocity (m/s) = 1.04×10^ -5 m³/s= 0.054 m/s
[Π (0.0156)² m² / 4]
Re = 0.054 (m/s) × 0.0156 m= 940.20.9025 ×10 ^ -6 (m²/s)
Turbulent flow
Average of time(s) = 84+98+85 = 89 s 3
Flow rate (m³/s) = 4 L = (0.0449L/s) × (0.001m³)= 4.49 × 10^ -5 m³/s
89 s 1 L
Velocity (m/s) = 4.49×10^ -5 m³/s= 0.235 m/s
[Π (0.0156)² m² / 4]
Re = 0.235 (m/s) × 0.0156 m= 4060.540.9025 ×10 ^ -6 (m²/s)
Lower critical velocity
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Average of time(s) = 676+695+657= 676 s 3
Flow rate (m³/s) = 4 L = (5.917 × 10 ^ -3 L/s) × (0.001m³)= 5.917 × 10^ -6 m³/s
676 s 1 L
Velocity (m/s) = 5.917 × 10 ^ - 6 m³/s= 0.031m/s [Π( 0.0156)² m² / 4 ]
Re = 0.031 (m/s) × 0.0156 m= 535.84 0.9025 ×10 ^ -6 (m²/s)
Upper critical velocity
Average of time(s) = 277+271+271= 273 s 3
Flow rate (m³/s) = 4 L = (0.0146 L/s) × (0.001m³)= 1.465 × 10^ -5 m³/s
273 s 1 L
Velocity (m/s) = 1.465 × 10 ^ - 5 m³/s= 0.0766m/s
[Π (0.0156)² m² / 4]
Re = 0.0766 (m/s) × 0.0156 m= 1324.1 0.9025 ×10 ^ -6 (m²/s)
After calculations results 15
Experiment 1
Flow type Flow rate (m³/s) Reynolds number
Laminar 4.45 × 10^ -6 397.56
Transitional 1.04 × 10^ -5 940.2
Turbulent 4.49 × 10^ -5 4060.54
Experiment 2
Velocity type Flow rate (m³/s) Reynolds number
Lower critical velocity 5.917 × 10^ -6 535.84
Upper critical velocity 1.465 × 10^ -5 1324.1
Discussion
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The experiment yielded Reynolds number of 397.56, 940.2, and 4060.54 for
laminar, transitional, and turbulent flows respectively. Now in theory, Reynolds number
of less than 2100 suggests that the flow is laminar. 2100 to 4000 Reynolds suggests
that is in transitional flow and higher than 4000 means that the flow is turbulent. There
was an error while doing this experiment as can be seen from our result. The reason
that we got 940.2 for transitional flow, when it was supposed to be between 2100 and
400 was because of the small flow rate that we used. The inlet and outlet valves were
hard to adjust to be optimal for our experiment. Furthermore, the dye that was used was
not thick enough and a strong flow would surely remove it from sight completely.
During observation of the experiment there was some clearly distinguishable
difference between the three flows encountered. Laminar flow for instance, rendered the
dye to move in a straight uninterrupted path. This was very easy to differentiate from the
other flow characteristic and as soon as this occurred, it was accepted as an ideal
condition that fits the definition in the lab manual which read that the dye would remain
as a solid, straight, and easily identifiable component of the flow. Transitional flow is
essentially a mix of characteristics between a laminar and a turbulent flow. Like and
unlike the laminar flow, the dye was straight on the top near the mouth of the injector
and then it turned wavy making its way down the observation tube. This is due to the
frictional energy loss. Because this type of flow is so close to turning turbulent, it was
really hard control the valves to get optimal transitioning. Turbulent flow was the easiest
to achieve overall. Just open both inlet and outlet valves and almost every time initially it
will be a turbulent flow. The definition of turbulent flow in the lab manual reads that it
(turbulent flow) denotes an unsteady flow condition where streamlines interact causing
shear plane collapse and mixing of the fluid. As stated recently, it was also observed in
the experiment where the dye that enters the observation tube was dispersed almost
immediately into the surrounding water. Another explanation to why this happens is that
there is a variety of rapid pressure and velocity going around in the tube.
The lower critical velocity is actually the velocity of flow changing from a laminar
flow to a more transitional flow. Upper critical velocity is the velocity of flow change from
turbulent to transitional. As seen in results of the experiment conducted, the flow
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velocities for both lower and upper critical velocity are 0.031m/s and 0.0766m/s m/s
respectively. The lower velocity verifies that the flow was from a laminar flow to
transition. There was an error however for the upper velocity part as it does not quite
show turbulence or transitional flow. This was due to the fact that only a small amount
of flow rate used just as in experiment 1. Reynolds number for lower critical velocity was
535.84 and the Reynolds number for upper critical velocity was determined to be
1324.1. As explained in the upper and lower critical flow velocity, the numbers for upper
critical value Reynolds number may not be near its theoretical value because of the
smaller amount of water flow rates used.
Parallax error may be a factor in why our results were off by some. The reading is
the 4L volume indicator might have been thrown a little off. As stressed in lots of part in
this discussion, the valves were just very sensitive. For instance when one valve is
lowered, another must be adjusted as well or it could potentially ruin the whole
experiment. Also there was leaking in some cases at the bottom of the tank since the
drain lid has to be manually put on. This may have affected the time taken to fill the tank
with 4 liters of water.
Sample calculations
Averagetime=904 s+892 s+898 s3
=898 s
Flowrate(m3s )= 4 L898 s
=4.45×10−3 Ls×0.001m3
1 L=4.45×10−6 m
3
s
V=V̇A
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Velocity (ms)=4.45×10−6m
2
s
π (0.0156 )2 m2
s
A=π D2
4
¿π (0.0156m) ²
4
¿1.911 x10⁻ ⁴m ²
ℜ=VDγ
ℜ=0.023 ms×0.0156m=397.56
Conclusion and recommendation
Conclusion
The results that we obtained from the calculations of the Reynolds number were
397.56 for laminar, 940.7 for transitional, and 4060.54 for turbulent. Although we cannot
say that the results are favourable when compared with the actual theory which the
Reynolds number for transitional flow should be between 2100 and 4000, a little part of
the theory was confirmed. The closer the result was to turbulent flow, the higher the
Reynolds number. Upper and the lower critical velocities obtained were 0.0766m/s and
0.031m/s. Where the values substituted into equation to obtain Reynolds number 535.84
for lower critical velocity and 1324.1 for upper critical velocity.
Recommendations
It is recommended that the water sink plug is changed to a more efficient design
so water leaks can be overcome faster and thus saving precious experiment time.
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The dye used during the experiment was not thick due to the face that I could
cause a blockage to the dye injector. It turns out that a few extra drop of dye
wouldn’t turn it into a worst case scenario. So in short, use a thicker dye.
The reading indicator for volume of water collected in the tank also needs some
improvement. A person with good eyes would have no problem reading the scale
but for some it might be more than a headache. A fine line on the scale indicating
0L and 4L would suffice.
References
1. "Reynolds, Osborne (RNLS863O)". A Cambridge Alumni Database. University of
Cambridge.pdf
2. Osborne Reynolds – Scientist, Engineer and Pioneer at
johnbyrne.fireflyinternet.co.uk.pdf
3. Osborne Reynolds- Engineer at johnbyrne.fireflyinternet.co.uk.pdf
4. Osborne Reynolds – Scientist at johnbyrne.fireflyinternet.co.uk.pdf
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