osborne reynold

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

10

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

10

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

20

discussion Discuss what the result and data mean; discuss and relate the result obtained with the theory

20

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

5

conclusion Relate the result obtained with the objective of the experiment

5

Recommendation -any improvement to be suggested by observing the inconsistencies observed in result/conclusion

5

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

8

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.

9

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)

11

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


1 4 84

2 4 98

3 4 85

Average 89

Lower critical velocity


1 4 676

12

2 4 695

3 4 657

Average 676

Upper critical velocity


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

13

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

16

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

18

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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osborne reynold

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