Composite Materials Engineering
ENGR 451: Transport Phenomena Laboratory
Drag
OUTCOMES
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Describe drag and explain its importance.
Define the various types of drags and their origin.
Derive the equation for drag coefficient of a falling object in a fluid.
List all the parameters that can affect the drag force.
Measure the drag coefficient of a sphere falling in a liquid as a function of
Reynolds number.
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INTRODUCTION
Read section 9-7 of Introduction to Fluid Mechanics (sixth edition) by Fox, McDonald,
and Pritchard.
MATERIALS AND EQUIPMENT
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Smooth spherical particles with different materials and densities
Tweezers
Timer
Armfield testing apparatus
Acetone wash bottle
500 CST Dow Corning 200 silicone oil (0.9557 g/cm3, 0.548 Pa*sec)
1000 CST Dow Corning 200 silicone oil (0.9720 g/cm3, 1.082 Pa*sec)
PROCEDURE
1. Clean all the particles with acetone.
2. Place a plastic sheet on the floor below the testing apparatus.
3. Before testing, make sure that there is oil up to the bottom of the particle insertion
tube. Oil can be found in the bucket below the testing tubes or in large white
canisters under the fume hood. (Caution: Makes sure that the correct oil is used
for each tube. Also be sure to wait until all air bubbles in the oil column have
worked their way to the top before beginning.)
4. Start with the 500 CST oil column.
5. Remove the rubber stopper from the top of the particle insertion tube.
6. Have a team member drop the particle into the column through the particle
insertion tube.
7. Record the time.
8. Remove the particle from the catch valve at the bottom of the column. Use gloves
and tweezers for this step. (Catch valve will clog if too many particles are
dropped)
9. Repeat steps six through eight at least three times for all particles.
10. Repeat with the 1000 CST oil column.
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