DISCUSSION :

Based on experiment conducted by Prof. Osborne Reynold in 1883, there are

three types of flow which is laminar, transitional and turbulent. It is necessary to know

the difference between laminar, turbulent, and transition flow before one is about to

conduct this experiment. This experiment was tested by using dye which was injected

into the flow water with different flow rate. Other than by observation, type of flow also

can be determine by calculation using Reynold’s Number formula.

The observation showed that during low water flow rate, laminar flow was

developed. We can know it was laminar as the dye travel in a straight line. But when the

flow rate was incresed a little bit, transitional flow start to show up. This is based on the

character of flow water which flow in straight line at the top and a little bit distrupt with a

little eddying at the bottom. Next, the dispersion started to increase indicating to

turbulent flow. When the flow rate was incresed to another value, turbulent flow was

produced. The dye injected was mix with the water because of high disturbance in the

water happened.

During the water flow change, from laminar to turbulent, it has no sudden

change, but there must be transition state in which the flow between laminar and

turbulent before it totally change to turbulent. Because of that there are two type of

critical velocity which is lower critical velocity and upper critical velocity. Lower critical

velocity is a velocity at which laminar flow stop, meanwhile, upper critical velocity is a

velocity at which turbulent flow starts

There are a few careless mistakes that have been done during this

experiment..The one who collect the fluid might not begin right when the person

monitoring the stopwatch ticking on it. Therefore the values calculated in results section

might not be exactly 100% correct. But based on our observation, the characteristic of

the dye produced is similar with the theory. We observe that, the blue dye shape

change from thin thread to sligthly swirlling at the lower part and still a thin thread at the

upper part. Then, the shape is change from slightly swirll to completely swirlling. We can

say that this change is from laminar to transitional and then, to turbulent.

DIAGRAM AND DESCRIPTION OF APPARATUS :

Figure 1 : Unit Assembly of Osborne Reynold’s Demostration (Model FM111)

This Osborne Reynold’s Demonstration apparatus is equipped with visualization tube,

as the observation tube to make it easier to observed the flow condition. The rocks

inside the head tank are to calm the inflow water so that there will not be any turbulence

to interfere with the experiment. The water inlet, outlet and dye injector are utilize to

generate the required flow.

Dye reservoir

Dye injector

Bell mouth

Observation tube

Water outlet valve, V2

Dye control valve, V4

Head tank

Overflow valve, V3

Water inlet valve, V1

PROCEDURES :

Experiment A

1. The injector was lower until it was seen in the glass tube.

2. The pump was open to allow the water flow.

3. The inlet valve, V1 were open and the water was allowed to enter stilling tank.

4. A small overflow spillage was ensure through the over flow tube to maintain a

constant level.

5. The water was allowed to settle for a few minutes.

6. The water flow was letting through the visualizing tube.

7. The dye control valve, V4 was slowly adjusted until a slow with dye injection was

achieved.

8. The water inlet valve, V1 and outlet valve, V2 was regulated until a straight

identifiable dye line was achieved. Laminar flow was determined.

9. The flow rate at the outlet valve, V2 was measured until 4L used volumetric

method. The time taken was recorded.

10.The experiment was repeated by regulating water inlet valve, V1 and outlet

valve, V2 for produced transitional and turbulent flow.

Experiment B

1. The injector was lower until it was seen in the glass tube.

2. The pump was open to allow the water flow.

3. The inlet valve, V1 were open and the water was allowed to enter stilling tank.

4. A small overflow spillage was ensure through the over flow tube to maintain a

constant level.

5. The water was allowed to settle for a few minutes.

6. The water flow was letting through the visualizing tube.

7. The dye control valve, V4 was slowly adjusted until a slow with dye injection was

achieved.

8. The procedure was repeated to create a laminar flow, the flow rate was slowly

increased until the laminar flow was produced at small disturbance or eddies.

These were lower critical velocity.

9. The flow rate at the outlet valve, V2 was measured until 4L used volumetric

method. The time taken was recorded.

10. The experiment was repeated by first introducing a turbulent flow and the flow

rate was slowly decreased until the flow became transitional. These were upper

critical velocity.

SAFETY AND PRECAUTION :

1.

REFERENCES :

Chemical Engineering Laboratory (CHE 331) prepared by UiTM Terengganu.

Donald F. Young, Bruce R. Munson Department of Aerospace Engineering and

Engineering Mechanics, Theodore H. Okiishi Department of Mechanical

Engineering at Iowa State University, Ames, Iowa, USA, Wade W. Huebsch

Department of Mechanical and Aerospace Engineering at West Virginia

University, Morgantown, West Virginia, USA, Wiley pages 274.

http://en.wikipedia.org/wiki/Osborne_Reynolds

http://en.wikipedia.org/wiki/Laminar_flow

http://en.wikipedia.org/wiki/Turbulence

http://en.wikipedia.org/wiki/Laminar-turbulent_transition

Optimization of Chemical Processes, 2nd Edition, Thomas F.Edgar , David M.

Himmelblau Department of Chemical Engineering University of Texas at Austin.

Leon S. Lasdon, College of Business Administration University of Texas at

Austin, Mc Graw Hill pages 448.