cewb121 exp 3 full report

UNIVERSITI TENAGA NASIONAL

COLLEGE OF ENGINEERING

DEPARTMENT OF CIVIL ENGINEERING

CEWB121 MECHANICS OF FLUID LABORATORY

EXP. TITLE : HB 024 OSBORNE REYNOLD APPARATUS

EXP. NO : 3

STUDENT NAME : NUR FAREHA BINTI ABDUL GHAFAR

STUDENT ID : CE096508

SECTION : 01

GROUP : 02

GROUP MEMBERS: 1. AZRUL AFFAN BIN MUHAMAD RASHIDI

CE096502

2. HARIGARAN A/L KANDASAMY

CE096504

3. MOHAMMAD OMAR HAMID WAGIEALLA

CE097089

INSTRUCTOR : PROF. IR. DR. MARLINDA BINTI ABDUL MALEK

Performed Date Due Date Submitted Date22 JUNE 2015 29 JUNE 2015 29 JUNE 2015

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TABLE OF CONTENT

TITLE PAGE

Objective 3

Theory 3

Anticipated Results 4

Apparatus 4

Procedure 5

Data, Observations and Results 6 - 8

Discussions 9

Conclusions 9

Critique 10

References 10

Appendix 11

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OBJECTIVE

The purpose of the experiment is to identify the differences between laminar, turbulent, and transitional fluid flow. The experiment is also to determine the Reynolds’s numbers for each of the flow. The design of the apparatus allowed studying the characteristic of the flow of the fluid in the pipe, the behavior of the flow and also to calculate the range for the laminar and turbulent flow where the calculation is used to prove the Reynolds number is dimensionless by using the Reynolds Number formula.

THEORY

Laminar and turbulent flow

Professor Osborne Reynolds (1842-1912) first realized that there was a ‘critical velocity’ at which the law relating loss of pressure energy and velocity in pipe flow changed. He first demonstrated this with his famous ‘Color Band’ (on the die-line) experiment. This consisted of injecting a line jet of dye into the flow of water visible through a transparent pipe. At low velocities the dye-line was unbroken, but as the velocity of the flow through the pipe was increased, the dye-line broke up and eddies were seen to form. From this and further experiments, he came to the conclusion that there are two distinct types of flow:-

1. Streamline or Laminar Flow (Latin lamina = layer of thin sheet). The fluid moves in layers without irregular fluctuation in velocity. Laminar flow occurs at low Reynolds Numbers. (The flow of oil in bearing is Laminar).

2. Turbulent flow. This results in the fluid particles moving in irregular patterns carrying an exchange of momentum from one portion of the fluid to another.

Reynolds investigated these two different types of motion and concluded that the parameters which were involved in the flow characteristics were

Ρ the density of the fluid kg/m3

v the velocity of the flow of the fluid m/sd Diameter of pipe mμ the coefficient of viscosity of the fluid Ns/m2

He arrived at a dimensionless constant (Reynolds number)

(Re)=ρvd/μ

The value of which was concerned with the fluid motion. Fluid motion was found to be laminar for Re numbers below 2000 and turbulent flows for Re greater than 4000.

Meanwhile, for numbers in between 2000 and 4000, it was stated to be transition.

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ANTICIPATED RESULTS

In this experiment, the flow condition for theory result should be tally with the flow condition for experiment.

If the experiment flow shows that the condition is Laminar, the calculated Reynolds Number for theory should be more than 2000.

If the experiment flow shows that the condition is Transition, the calculated Reynolds Number for theory should be between 2000 and 4000.

Lastly, if the experiment flow shows that the condition is Turbulent, the calculated Reynolds Number for theory should be more than 4000.

APPARATUS

The apparatus that we used provides laminar, translational and turbulent flow as predicted by Osborne Reynolds. Main components of the apparatus:

Acrylic tank with an adjustable constant head Glass tube ID 12mm and length 720 mm with whiteboard background Water is admitted at the bottom of the tank through a diffuser and stilling materials. Water is discharged via a bell mouth transparent tube with a flow control valve at the

end Dye reservoir 0.5 liter with control valve and injection needle Measuring cup 2.0 liter

The apparatus must be used in conjunction with Hydraulics Bench

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PROCEDURE.

1. The Hydraulics Bench to level position as Hydraulics Bench Manual.

2. The HB 024 Osborne Reynolds is placed on the table just outside the bench such that

discharge can still be made on the bench measuring tank. This is to eliminate any

disturbance on the stream line due to bench vibration. The screw at the base is

adjusted for level and water supply hose is connected from the Bench to the test

equipment.

3. The dye reservoir is put on the water tank and the needles is adjusted to center line of

the tube slightly protruding into the bell mouth

4. The dye valve is slightly opened for a small flow such that the stream lines of the dye

are sharp.

5. The water temperature is recorded as 30oC

6. By visual view, the test equipment discharged valve is slowly controlled to obtain

laminar, transition and turbulent flow and the flow rate is measured by measuring cup.

7. The calculated Re is compared and the flow condition is observed

8. The flow rate versus Re graph is plotted

9. The result is discussed.

5

DATA, OBSERVATIONS AND RESULTS

Volume of Time (s)

Flow Rate Kinematic VelocityRe

Condition (flow) water (ml) (m3/s) viscosity (m2/s) (m/s) Exp Theory

100 08.68 1.15 x 10-5 8.03 x 10-7 0.1018 1521.30 Laminar Laminar





100 07.03 1.42 x 10-5 8.03 x 10-7 0.1257 1878.46 Transition Laminar




500 32.47 1.54 x 10-5 8.03 x 10-7 0.1363 2036.86 Transition Transition

100 04.03 2.48 x 10-5 8.03 x 10-7 0.2195 3280.19 Turbulent Transition

200 05.70 3.51 x 10-5 8.03 x 10-7 0.3106 4641.59 Turbulent Turbulent




6

Graph

7

Calculations

The Flow Rate is calculated by the following formula:

Flow rate, Q : Volume (m3) Time (sec)

Volume : 100 ml ; 0.0001m3

Q = 0.0001m 3 08.68 s

= 1.15 x 10-5 m3/s

The Kinematic viscosity, ν is obtained by:

Referring to appendix A, the kinematic viscosity for water at temperature 30oC is

8.03x10-7 m2/s

The Velocity is calculated by the following formula:

V = Q/A

Where A = Πd2

4A= (22/7) (0.012)2

4 = 1.13x10-4 m2

So, V = 1.15 x 10-5 m3/s 1.13x10-4 m2

= 0.1018 m/s

The Reynolds Number is calculated by the following formula:

Re = Vd /ν

= 0.1018 (0.012) 8.03x10-7

= 1521.3

Since 1521.3 is less than 2000, so it is laminar.

*(The other calculations are done using the same steps.)

8

DISCUSSION By comparing the result that we get from the observed flow condition and the

calculated Reynolds Number, there are a bit different between the results collected. For the laminar flow we managed to tally the condition from the first 100 ml until 500 ml of water. When it comes to the transition part, even though we observe the flow is in transition condition, however when we calculate the Reynolds Number the value that we get is fulfilled the laminar condition and not transition condition. For the first 100 ml until 400 ml, the values of Reynolds Number that we calculated are lesser than 2000 thus proved it to be in laminar flow. For the 500 ml, again we managed to get tally the value for both experiment and theory as we managed to get value between 2000 and 4000 (prove it to be transition flow). As for turbulent flow, there is only slight difference between the experiment and the theory. The first 100 ml we get the value for transition flow but for the next 200 ml until 500 ml, we managed to get the turbulent flow condition. The errors that occurred might be comes from parallax error such as the position of eyes during taking the value of water volume and the slow response when taking the value time. During the experiment there are several precaution steps that need to be alert. The experiment should be done on a stable place. When taking the water volume, one of our member just hold the measuring cup instead of put it on the table. So this might contribute to error for this experiment. Other than that, to get appropriate laminar smooth stream flow, the clip and the valve which control the purplish dye must be regulate slow and carefully. The graph of Flow Rate versus Reynolds Number that we plotted based on our result shows that as the water flow rate increase, the Reynolds number calculated also increase.

. CONCLUSION

As a conclusion, the initial objective are met because we are able to conduct the experiment well and the result obtained is just slightly varies with the actual one. We managed to calculate the flow rate, velocity and Reynolds Number effectively by calculate it using the provided formula. We are also able to plot the graph of Flow rate versus Reynolds Number. The result varies because there are some errors occurred during conducting the experiment as stated in the discussion part.

9

CRITIQUE

We successfully conduct our experiment by referring the lab manual. The problem is just that it is very hard to control the dye flow especially when to get a straight line for laminar flow. Other than that, everything is fine.

REFERENCES

1. Mechanics of Fluid Laboratory CEWB121, Lab Manual, Experiment 3 :

HB 024 Osborn Reynold Apparatus

2. Reynolds Experiment video- https://www.youtube.com/watch?v=Kq9UKD0iZ2Q3. How Reynolds Apparatus works- http://theconstructor.org/practical-guide/reynolds-

experiment/2052/

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cewb121 exp 3 full report

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