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TABLE OF CONTENT
- 1 Abstract………………………………. No Title Page
- 2 Introduction…………………………..
- 3 Objectives……………………………..
- 4 Theory………………………………... 5 –
- 5 Material And Apparatus……………… 7 –
- 6 Methodology………………………….
- 7 Data and Results………………………
- 8 Calculations…………………………... 11 –
- 9 Discussion…………………………….
- 10 Conclusion…………………………….
- 11 Recommendations…………………….
- 12 Reference……………………………...
- 13 Appendix……………………………...
1.0 ABSTRACT
Osborne Reynolds experiment is used to investigate the characteristic of the flow of the liquid in the pipe which is also used to determine the Reynolds Number for each state 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, transitional and turbulent flow where the calculation is used to prove the Reynolds number is dimensionless by using the Reynolds Number formula.
For the first and second objectives, it involves running the Osborne Reynolds equipment with different of water volume flow rate. In this experiment we fix the volume, which is 0.3 L amount of water while the time is recorded to obtain its volume flow rate. At the same time we also observe the characteristic of the flow, whether there are laminar, transitional or turbulent flow. From the data collected we made calculation to estimate the range for laminar, transitional and turbulent flow. To prove that the Reynolds number is dimensionless, we calculate by using the units only and using the appropriate formula. By that, it is proved that the Reynolds number is dimensionless parameter.
3.0 OBJECTIVE
The purpose of the Osborne Reynolds Experiment is to illustrate laminar, transitional and turbulent pipe flows and to determine the condition under which these type of flow occurs. The examples of flow that we should get from the experiment are:
Laminar flow is the type of flow in which the particles move in a straight line in the form of a thin parallel sheets is known as the Laminar flow. Laminar flow denotes a steady condition where all stream lines follow parallel paths. Under this condition, the dye will remain easily identifiable as a solid core.
Turbulent flow is the type of flow in which the particles move in a zigzag pattern is known as the turbulent flow. Turbulent flow denotes as unsteady condition where stream lines interact causing shear plan collapse and mixing occurs. As the flow rate is increased, the transition from laminar to turbulent flow is a gradual process. This zone of change is defined as transitional flow. This will appear as a wandering dye stream prior to dispersion as turbulence occurs.
Transitional flow is when the flow changes from laminar to turbulent or vice verse a disturbance is created, it is called as the transitional flow.
1) Experiment A
Experiment objectives:
To compute Reynolds number (R). To observe the laminar, transitional and turbulent flow.
2) Experiment B
Experiment objectives:
To determine the Reynolds number (R) To determine the upper and lower critical velocities at transitional flow.
4.0 THEORY
The theory is named in honor of Osborne Reynolds, a British engineer who discovers the
variables that can be used as a criterion to distinguish between laminar and turbulent flow.
The Reynolds number is widely used dimensionless parameters in fluid mechanics.
Reynolds number formula:
R =
R = Reynolds number
U = Fluid velocity, (m/s)
L = characteristic length or diameter (m)
V = Kinematic viscosity ( /s)
Reynolds number R is independent of pressure
5.0 MATERIAL AND APPARATUS
Material
- Water
- Dye
Apparatus
Beaker
Stop Watch
- Solteq® Osborne Reynolds Demonstration (Model: Fm 11)
Figure 1: Unit Assembly of Osborne Reynolds Demonstration (Model: FM11)
- Dye reservoir 6) Overflow tube, V
- Dye control valve, V4 7) Water inlet valve, V
- Dye injector 8) Bell mouth
- Head tank 9) Water outlet valve, V
- Observation tube
1 2 3 4 5 6 7
9
8
7.0 DATA AND RESULTS
Laminar Flow
Volume (L)
Time (s)
Flow rate, Q (L/s)
Flow rate, Q (m^3 /s)
Fluid Velocity, U (m/s)
Reynolds Number 0.3 23 0.0130 1.3000 x 10-5^ 0.0736 1240. 0.3 23 0.0130 1.3000 x 10-5^ 0.0736 1240. 0.3 28 0.0107 1.0700 x 10-5^ 0.0606 1021.
Transitional Flow
Volume (L)
Time (s)
Flow rate, Q (L/s)
Flow rate, Q (m^3 /s)
Fluid Velocity, U (m/s)
Reynolds Number 0.3 16 0.0188 1.8800 x 10-5^ 0.1064 1793. 0.3 12 0.0250 2.5000 x 10-5^ 0.1415 2384. 0.3 11 0.0273 2.7300 x 10-5^ 0.1545 2603.
Turbulent Flow
Volume (L)
Time (s)
Flow rate, Q (L/s)
Flow rate, Q (m^3 /s)
Fluid Velocity, U (m/s)
Reynolds Number 0.3 5 0.0600 6.0000 x 10-5^ 0.3396 5723. 0.3 7 0.0429 4.2900 x 10-5^ 0.2428 4092. 0.3 5 0.0600 6.0000 x 10-5^ 0.3396 5723.
Laminar to Transitional Flow
Volume (L)
Time (s)
Flow rate, Q (L/s)
Flow rate, Q (m^3 /s)
Fluid Velocity, U (m/s)
Reynolds Number 0.3 15 0.0200 2.0000 x 10-5^ 0.1132 1907. 0.3 16 0.0188 1.8800 x 10-5^ 0.1064 1793. 0.3 15 0.0200 2.0000 x 10-5^ 0.1132 1907.
Turbulent to Transitional Flow
Volume (L)
Time (s)
Flow rate, Q (L/s)
Flow rate, Q (m^3 /s)
Fluid Velocity, U (m/s)
Reynolds Number 0.3 12 0.0250 2.5000 x 10-5^ 0.1415 2384. 0.3 12 0.0250 2.5000 x 10-5^ 0.1415 2384. 0.3 12 0.0250 2.5000 x 10-5^ 0.1415 2384.
8.0 CALCULATIONS
Sample Calculation of Flow Rates , Q
Laminar Flow Transitional Flow Turbulent Flow
Sample Calculation of Fluid Velocity, U
Laminar Flow Transitional Flow Turbulent Flow
Critical Laminar to Transitional Flow (Lower Critical Velocity)
Critical Turbulent to Transitional Flow (Higher Critical Velocity)
Sample Calculation of The Reynold Number, Re
Where, Re = Reynolds number U = Fluid Velocity, (m/s) D = Diameter ( V = Kinematic viscosity (
Laminar Flow Transitional Flow Turbulent Flow
⁄ ⁄
Critical Laminar to Transitional Flow Critical Turbulent to Transitional Flow
⁄ ⁄
10.0 CONCLUSION
The laminar flow occurs when the fluid is flowing slowly and the turbulent flow occurs when it is flowing fast. In transitional flow, the flow switches between laminar and turbulent in a disorderly fashion.
As the water flow rate increase, the Reynolds number calculated also increase and the dye line change from thin thread to swirling in shape Laminar flow occurs when the Reynolds number calculated is below than 230 0 ; t r a n s i t i o n a l flow occurs when Reynolds number calculated is between 2300 and 4000 while turbulent flow occurs when Reynolds number calculated is above 4000.It is proved that the Reynolds equation is dimensionless, no units left after the calculation.
.
Under most practical conditions, the flow in a circular pipe is laminar for Re ≤ 2300, turbulent for Re ≥ 4000 and transitional in between. That is,
Re ≤ 2300 laminar flow
2300 ≤ Re ≤ 4000 transitional flow
Re ≥ 4000 turbulent flow
11.0 RECOMMENDATION
Based on this experiment, there are many ways to improve the experiment and obtain the best results. Firstly, the experiment should be repeated three times in order to get average readings. This will reduce the deviation from theoretical results. The experiment itself took a more four hours to be done once, so with insufficient time, the experiment could only be done once. To get better results, the experiment should have been repeated at least twice.
While conducting the experiment, there are some error such as the slow response when collecting the water in the beaker once we get the flow (laminar, turbulent or transition flow). Besides, the slow response to start the time taken for the volume of water and regulating the valve which control the flow rate of water. So, the person in charged should be more alert and focus during the experiment in order to obtain the accurate result. There are also some parallax error while conducting the experiment. For instant, the position of the eyes during taking the value of water volume of 300mL is not in the same level with the readings. Therefore, the readings taken from the beaker should be taken at eye level which is perpendicular to our eyes to avoid parallax error.
So, 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 blue dye must be regulate slow and carefully. When removing the beaker from the exit valve, we notice that some water still enter the beaker. So, to avoid this it is better to take same person who guard the stop watch and the collecting beaker.
Last but not least, we must study the manual lab that have been given to us before start up the experiment. We also can improve our skill and knowledge to ensure that experiment can be done smoothly.
13.0 APPENDIX
Laminar Flow Transitional Flow
Turbulent Flow
