Fluid Mechanics Lab

Posted by : Asad Ali Arshad Wednesday 21 February 2018

To compute the Reynolds’s Number and to observe the Laminar, Transitional and Turbulent Flow
(Osborne Reynolds’s Demonstration Unit)

Theoratical Background.

Reynold’s No:

ØThe Reynolds number (Re) is an important dimensionless quantity in fluid mechanics used to help predict flow patterns in different fluid flow situations.

ØIt is the ratio of inertial forces to viscous forces within a fluid which is subjected to relative internal movement due to different fluid velocities.

ØIt is used to predict the transition from laminar to turbulent flow.

Ølaminar flow occurs at low Reynolds numbers, where viscous forces are dominant, and is characterized by smooth, constant fluid motion.

turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, which tend to produce chaotic eddies, vortices and other flow instabilitie.

Procedure:

1. Lower the dye injector until it is seen in the glass tube.

2. Open the inlet valve and allow water to enter stilling tank.

3. Ensure a small overflow spillage through the over flow tube to maintain a constant level.

4. Allow water to settle for a few minutes.

5. Open the flow control valve fractionally to let water flow through the visualizing tube.

6. Slowly adjust the dye control needle valve until a slow flow with dye injection is achieved.

7. Regulate the water inlet and outlet valve until an identifiable dye line is achieved.

8. Measure the flow rate using volumetric method i-e collect the water from the outlet having

die in it in a volumetric tank and calculate the time with a stop watch.

9. Repeat the experiment by regulating water inlet and outlet valve to produce different flows