osborne reynolds apparatus lab report PDF

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CEWB1021 MECHANICS OF FLUIDS LABORATORY SEMESTER 2 2020/2021

Section : 01 Experiment 3 : HB 024 OSBORNE REYNOLD APPARATUS Lecturer’s Name : Hidayah Bte Basri, Ir.

List of Group: No Name . 1 Areef Adham Bin Suffian 2 Ravinder Singh 3 Muhammad Saiful Hakim bin Mohd Sufian

ID No. CE0106961 CE0107099 CE0106685

Introduction Laminar Flow When the flow is very slow, the molecules of the fluid will move in layers parallel to the pipe wall in the direction of the flow. The molecules at the center of the pipe move much faster than the molecules near the wall. This state of flow is called laminar flow. Turbulent Flow When the flow is very fast, the molecules have an irregular motion in diffused pattern but, in general, in the direction of flow with nearly the same velocity across the diameter except molecules near pipe wall move only slightly slower than the molecules at the center of the pipe. This state of flow is called turbulent flow. Flows in most cases of engineering study is turbulent flow. Reynolds Number Type of flow may be indicated by a dimensionless quantity called Reynolds Number (Re). Re = ρ

ρVd µ

=

Vd ν

= Density of the fluid, kgm/m3

V = Velocity, m/s D = Tube diameter, m μ = Dynamic viscosity, Pas or kg/ms ν

= Kinematic viscosity, m2/sec

Flow is laminar when Re is 2000 or less and is turbulent when Re is 4000 or more. Transition range is when Re is between 2000 and 4000.

Objective The objective of this lab experiment is to illustrate laminar, transitional, and fully turbulent flows in a pipe, and to determine under which conditions each flow regime occurs.

Procedure 1. The Hydraulics Bench was set to level position as Hydraulics Bench Manual. 2. HB 024 Osborne Reynolds was placed on a table just outside the Bench such that discharge can still be made to the Bench measuring tank. This is to eliminate any disturbance on the streamline due to bench vibration. The screw at the base was adjusted for level and water supply hose was connected from the Bench to the test equipment. 3. Dye reservoir was put on the water tank and the needles was adjusted to center line of the tube slightly protruding into the bell mouth. 4. The dye valve was slightly opened for a small flow such that the streamlines of dye were sharp.

5. Water temperature was recorded as 30oC. 6. By visual view, the test equipment discharge valve was slowly controlled to obtain laminar, transition and turbulent flow and flow rate was measured by measuring cup.

7. The calculated Re was compared with the observed flow condition. 8. Graph flow rate versus Re was plotted. 9. The results were commented. Results & analysis Flow rate(Q) = Volume/Time

Velocity = Q/Area, tube diameter (d) = 12 mm Area = π d3/4 = ( π

Water kinematic viscosity at 30oC ( ν ) = 8.009 x 10-7 m2/s

x (12x10-3)3)/4 = 1.357x10-6 m2 Re = 4Q/πd ν

Volume of water (ml)

Time (sec)

Flow rate (m3/s)

Kinematic viscosity (m2/s)

Velocity (m/s)

Re

100 200 300 400 500 100 200 300 400 500 100 200 300 400 500

45.33 97.75 153.84 226.74 293.91 3.58 7.91 11.01 17.93 20.86 2.22 1.91 2.01 1.93 1.86

0.2206x10-5 0.2046x10-5 0.1950x10-5 0.1764x10-5 0.1701x10-5 2.7933x10-5 2.5284x10-5 2.7248x10-5 2.2309x10-5 2.3969x10-5 4.5045x10-5 10.4712x10-5 14.6254x10-5 20.7254x10-5 26.8817x10-5

8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7 8.009x10-7

1.6256 1.5077 1.4370 1.2999 1.2535 20.5844 18.6323 20.0796 16.4399 17.6632 33.1945 77.1643 107.7775 152.7296 198.0965

292.25 271.05 258.34 233.69 225.35 3700.57 3349.63 3609.82 2955.50 3175.42 5967.57 13872.25 19375.74 27457.03 35612.90

Condition (flow) Experimen Theory t Laminar Laminar Laminar Laminar Laminar Transition Transition Transition Transition Transition Turbulent Turbulent Turbulent Turbulent Turbulent

Laminar Laminar Laminar Laminar Laminar Transition Transition Transition Transition Transition Turbulent Turbulent Turbulent Turbulent Turbulent

Discussion & conclusion The experiment was carried out 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 experiment was also done to know and learn the behavior of the flow. There are three types of flow that we study in this experiment. Firstly, laminar flow which is the type of flow in which the particles move in a straight line in the form of a thin parallel sheets. Laminar flow denotes a steady condition where all stream linesfollow parallel paths. Under this condition, the dye will remain easily identifiable as a solid core.Then, turbulent flow which is the type of flow in which the particles move in a zigzag pattern. Turbulent flow denotes as unsteady condition where stream lines interact causing shear plan collapse and mixing occurs. Lastly is transitional flow when the flow changes from laminar to turbulent or vice versea disturbance is created, it is called as the transitional flow. This will appear as a wandering dye stream prior to dispersion as turbulence occurs. In this experiment, we observed that the dye line change with the increasing of water flow rate. The shape 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. We must control the valve until the flow formed.

In 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 2000, transitional flow occurs when Reynolds number calculated is between 2000 and 4000 while turbulent flow occurs when Reynolds number calculated is above 4000....