UNIVERSITI TEKNOLOGI MARA FAKULTI KEJURUTERAAN KIMIA

PROCESS ENGINEERING LABORATORY I(CPE453)

No. Title Allocated Marks (%) Marks1 Abstract/Summary 5  2 Introduction 10  3 Aims 5  4 Theory 10  5 Apparatus 5  6 Methodology/Procedure 10  7 Results 10  8 Calculations 10  9 Discussion 20  10 Conclusion 5  11 Recommendations 5  12 Reference / Appendix 5  

TOTAL MARKS 100  

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NAME : MUHAMMAD AZIZI BIN MOHD ZULKIFLISTUDENT NO. : 2014248582GREXPERIMENT : OSBORNE REYNOLDS APPARATUSDATE PERFORMED : 12TH OCTOBER 2015SEMESTER : 3PROGRAMME / CODE : EH241 3ASUBMIT TO : MISS HABSAH ALWI

ABSTRACT

Osborne Reynolds experiment is used to investigate the characteristic of the flow of the liquid

in the pipe. This experiment is also can determine the Reynolds Number for each state of the

flow.  Reynolds Number had been compute and the type of flow had been observed by the

pattern of the ink dye either it was laminar, transitional or turbulent flow. The velocity of the

flow was control by the valve to differentiate the type of the flow. The time had been

calculated for each of the flow to fill the tank exactly with 2 litre. The Reynolds Number had

been calculated by using the Reynolds Number formula, Re ¿ρvdμ  .

From the experiment it was proved that the laminar flow fall in range of 0 to 2100, transition

state range between 2100 to 4000 and turbulent flow had Reynolds Number more than 4000. 

INTRODUCTION

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Reynolds most famously studied the conditions in which the flow of fluid in pipes

transitioned from laminar flow to turbulent flow. From these experiments came the

dimensionless Reynolds number for dynamic similarity is the ratio of inertial forces to

viscous forces. In fluid dynamics, turbulence or turbulent flow is fluid regime characterized

by chaotic and stochastic property changes. This includes low momentum diffusion, high

momentum convection, and rapid variation of pressure and velocity in space and time.

Laminar flow, sometimes known as streamline flow, occurs when a fluid flows in parallel

layers, with no disruption between the layers. At low velocities the fluid tends to flow

without lateral mixing, and adjacent layers slide past one another like playing cards. There

are no cross currents perpendicular to the direction of flow, nor eddies or swirls of fluids. In

laminar flow the motion of the particles of fluid is very orderly with all particles moving in

straight lines parallel to the pipe walls. In fluid dynamics, laminar flow is a flow regime

characterized by high momentum diffusion and low momentum convection. When a fluid is

flowing through a closed channel such as a pipe or between two flat plates, either two types

of flow may occur depending on the velocity of the fluid: laminar flow or turbulent flow.

Laminar flow is the opposite of turbulent flow which occurs at higher velocities where eddies

or small packets of fluid particles form leading to lateral mixing. In nonscientific terms

laminar flow is smooth, while turbulent flow is rough.

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THEORY

Reynolds number, Re formula can be identified the transition from laminar to

turbulent flow occurs at a definite value of the dimensionally property:

Re = ρvdμ

Where:

v = velocity = QA

d = pipe diameter

Q = volumetric flow rate = vt

μ = viscosity

A = cross sectional area of cylinder glass tube

ρ = density

V = volume of the flow

t = time taken (s)

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Above picture shows three flow regimes, that is:

(a) Laminar

(b) Transitional

(c) Turbulent

Flow in which the kinetic energy dies out due to the action of fluid molecular viscosity is

called laminar flow. While there is no theorem relating Reynolds number to turbulence, flows

with high Reynolds numbers usually become turbulent, while those with low Reynolds

numbers usually remain laminar. For pipe flow :

Re 4000 = turbulent flow

Re < 2100 = laminar flow

2100 < Re < 4000 = transition region

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OBJECTIVES

1. To observe the characteristics of laminar, transition and turbulent flow

2. To prove that the Reynolds number is dimensionless by using formula

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APPARATUS

A) Osborne Reynolds Demonstration apparatus which consist :

1. Hydraulic bench model FM110

2. Ink dye injector

3. Ink dye reservoir

4. Bell mouth

5. Water inlet valve

6. Clear observation tube

7. Control valve

8. Overflow pipe

9. Water outflow pipe

10. Water inflow pipe

11. Head tank

12. Overflow valve

13. Water inflow valve

14. Water outflow valve

Figure 1 : Hydraulic bench Model FM 110

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Figure 2 : Ink dye injector Figure 3 : Flow pipe

B) Beaker and measuring cylinder

C) Stopwatch

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PROCEDURE

1. Set up the apparatus before the experiment started.

2. The main switch is switched on.

3. The head tank is filled by water until the water level reached higher than aluminium

rod using the control valve.

4. The ink dye injector is opened during the experiment and let the ink flowed through

the observation tube and let the amount of ink flow is fixed.

5. The amount of water that flow out through the out flow pipe is taken in 10 seconds by

using measuring cylinder in order to calculate the flowrate.

6. The pattern of dye ink flow through the observation tube is been observed.

7. The experiment is repeated for three times to get the average volume.

8. The experiment is repeated with different type of flow by adjust the over flow valve.

9. The data is recorded. The Reynolds number is calculated and tabulated for the three

types of flow.

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RESULT.

Pattern of the three different flows :

A) Laminar flow

B) Transition flow

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C) Turbulent flow

Type offlow

Volume (ml) Average volume

(ml)Q

(l/s)Q

(m3/s)Reynolds NumberReading 1 Reading 2 Reading 3

Laminar flow 100 102 99.5 100.5 0.1005 1.005×10−5 922.29

Transitionflow 260 223 224 235.7 0.02357 2.357 ×10−5 2163.00

Turbulent flow 460 480 460 466.7 0.04667 4.667 ×10−5 4282.91

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CALCULATIONS

Diameter, d : 0.0156 m

Kinematic coefficient, : 0.89 ×10−6m2/ s

Area, A : πr2 = π( 0.01562

)2

= 1.91×10− 4m2

A) Laminar flow

Average volume : 100+102+99.5

3 = 100.5 ml = 0.1005 l

Flowrate, Q : volumetime = 0.1005

10 = 0.01005 ml/s = 1.005×10−5m3/ s

Reynolds number, Re : QdAµ = (1.005×10−5)(0.0156)

(1.91×10−4)(0.89×10−6) = 922.29

B) Transition flow

Average volume : 260+223+224

3 = 235.7 ml = 0.2357 l

Flowrate, Q : volumetime = 0.2357

10 = 0.02357 ml/s = 2.357×10−5m3/ s

Reynolds number, Re : QdAµ = (2.357×10−5)(0.0156)

(1.91×10−4)(0.89×10−6) = 2163.00

C) Turbulent flow

Average volume : 460+480+460

3 = 466.7 ml = 0.4667 l

Flowrate, Q : volumetime = 0.4667

10 = 0.04667 ml/s = 4.667×10−5m3/ s

Reynolds number, Re : QdAµ = (4.667×10−5)(0.0156)

(1.91×10−4)(0.89×10−6) = 4282.91

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DISCUSSION

Laminar flow is highly ordered fluid motion with smooth streamlines. Transition flow is a

flow that contains both laminar and turbulent regions while turbulent flow is a highly

disordered fluid motion characterized by velocity and fluctuations and eddies.

According to the Reynolds`s experiment, laminar flow will occur when a thin filament of

ink dye injected into laminar flow appears as a single line. There is no dispersion of ink dye

throughout the flow, except the slow dispersion due to molecular motion. While for turbulent

flow, if the ink dye filament injected into a turbulent flow, it disperse quickly throughout the

flow field, the lines of dye breaks into myriad entangled threads of dye.

In this experiment we have to firstly is to observe the characteristic of the flow of the fluid in

the pipe, which may be laminar or turbulent flow by measuring the Reynolds number and the

behaviour of the flow, secondly to calculate the range for the laminar and turbulent flow and

lastly to prove that the Reynolds number is dimensionless by using the Reynolds number

formula. After complete preparing and setup the equipment we run this experiment. But

firstly we have to calculate the area of bell mounted glass tube, the viscosity of water and the

density of water. The density of water is 1000 kg/m³, the area of glass tube is 1.91×10− 4m2

while the viscosity of water is 0.89 ×10−6m2/ s. This is done for easy step by step calculation.

We observe that the ink dye line change with the increasing of water flow rate. The pattern

change from thin threads to slightly swirling which still contains smooth thin threads and then

fully swirling. We can say that this change is from laminar flow to transitional flow and then

to turbulent flow and it is not occurs suddenly.

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CONCLUSION

As a conclusion, as water flow rate is increasing, the Reynolds number will automatically

increase as well, and the red dye line change from straight line to swirling streamlines.

Likewise, it is proven that the Reynolds number is dimensionless, since no unit is

representing the value of Reynolds number. Laminar flow is obtained if the Reynolds number

is less than 2100; meanwhile the Reynolds number for turbulent flow is more than 4000. The

Reynolds number for transition flow is in between 2100 until 4000.

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RECOMMENDATION

Compare with the result diagram in the laboratory, there are bit different between the results

collected. This might be some of parallax error such as the slow response during collecting

the water, the position of eyes during taking the value of water volume, time taken for the

volume of water and regulating the valve which control the flow rate of water unstably.

During the experiment there are several precaution steps that need to be alert. The experiment

should be done at suitable and unshaken place. To get appropriate laminar smooth stream

flow, the clip and the valve which control the injection of red dye must be regulate slow and

carefully. When removing the beaker from the exit valve, we notice that some water still

enter the beaker because of the slow response between the person who guide the stop watch

and collecting beaker.

So to avoid this parallax error, it is better to take same person who guard the stopwatch and

the collecting beaker. Lastly, do this experiment at steady place, control the clip and valve

carefully to get long thin of laminar dye flow, and remove the beaker which uses to collect

the amount of water at sharp when the time is up, to avoid error flow rate error. The

experiment can be repeated twice to get an accurate and better result.

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REFERENCES

Lecture note Fluid Mechanics, Dr Atikah Kadri

High-Reynolds number Rayleigh-Taylor turbulence. D.Livescu; J.R.Ristorcelli;

R.A.Gore; S.H.Dean; W.H.Cabot; AWCook. 1st January 2009.

Fluid Mechanics by Dr. Andrew Sleigh (J. Franzini / E. Finnemore),McGraw Hill.

F. M. White, Fluid Mechanics (Mc-Graw Hill, Inc., New York,1994).

www.pipeflow.co.uk

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APPENDIX

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