BACKGROUND
The flow in a pipe (closed conduit) is different from the stream which occurs through the open channel. Flow through a pipe takes place at a pressure, and it does not require any free surface.1
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There is three distinct flow in a pipe which are differentiated by Reynolds Number.
- Laminar Flow
- Transient Flow
- Turbulent Flow
The name “Reynolds Number” was given to honor “Osborne Reynolds” in the 19th century. Osborne Reynolds has conducted an experiment in which he has demonstrated two different types of flow. The experiment was performed by injecting a thin stream of colored fluid of the same density of water into a long transparent water flowing tube. The Reynolds number is a function of many intangible fluid properties, such as flow velocity, fluid density, pipe diameter, and fluid viscosity.2
i.e. R = f (V, ρ, μ (or ν), D)
and R = (V*D*ρ) / μ
where R = Reynolds number,
μ = dynamic viscosity
ν = kinematic viscosity,
V = flow velocity
D = Pipe diameter
Reynolds number (R) is also defined as a ratio of inertial or destabilizing force to the viscous damping or stabilizing force. With the increase in the value of R, the fluid flow gets into full-blown turbulence as the inertial flow becomes relatively larger. This experiment determines critical Reynold’s number at which the flow transformation of laminar flow into transient and turbulent takes place.3
The primary purpose of this experiment is to perform on Reynold’s apparatus to study the different properties of a fluid.
REQUIREMENTS
Materials:
Osborne Reynold’s Apparatus
Tap Water
Stopwatch
PROCEDURE
First of all, turn on the water supply and start the apparatus. Now, at the base of the apparatus, partially open the discharge valve. After this, adjust the amount of water till the constant head level goes just above the overflow pipe. Then, the water level is maintained by a small flow located at just below the overflow pipe.
Now, open the dye injector valve and adjust it to obtain a fine filament of dye. In the complete process, note down that the laminar condition has been achieved so that the dye filament passes entire tube length without any problem. Now, record the water temperature through a thermometer, and then measure its flow rate by timing the collection of the known quantity of water.
After this, increase the flow rate to a point till where disturbance increases and the rapid diffusion of dye filament takes place. Alas, gradually slow down the flow rate supply until the dye transforms into a steady thread laminar flow. Note down the temperature and flow rate at his point.
CONCLUSION
The experiment on Reynold’s number apparatus has been discussed, and different flows of fluid have been considered. Critical Reynolds number is a point on which conversion of the laminar flow into the transient, and the transient flow into the turbulent flow takes place.
REFERENCES
- M. S. S. T. Mikio Hino, “Experiments on transition to turbulence in an oscillatory pipe flow,” Journal of Fluid Mechanics, vol. 7, no. 2, pp. 193-207, 1976.
- Sadatoshi Taneda, “Experimental Investigation of the Wake behind a Sphere at Low Reynolds Numbers,” Journal of the physical society of japan, vol. 11, no. 3, pp. 1104-1108, 1956.
- F. K. B. C. D. Winant, “Vortex pairing : the mechanism of turbulent mixing-layer growth at moderate Reynolds number,” Journal of Fluid Mechanics, vol. 63, no. 2, pp. 237-255, 1974.
Also read:
- Experiments on Flow through Pipes
- Determination of Performance of Kaplan Turbine
- Determination of CV and CD of Orifices
- Determination of Metacentric Height and Application to Stability of Floating Bodies
- Experiments on Performance of Francis Turbine
- Experiments on Impact of Jets
- Experiments on Performance of Centrifugal Pump
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