Wind Tunnel Laminar and Turbulent Boundary Layer Development
I would like to describe the experiment. The main goal of this experiment was to measure
and compare the boundary layer thickness and visualize the transition from laminar to
turbulent flow. As for procedure, it has some similarities with previous experiments but in
my opinion it is easier than previous ones.
In addition, I would like to say that we used the principles from the nozzle. It is one of the main
types of ducts which increases the velocity of the flow and decreases the pressure. We have
studied it in Aerodynamics course.
2. Data records & error analysis
IX.Questions
Boundary Layer Thickness
The boundary layer thickness refers to the distance from the plate surface where the airspeed
reaches the free-stream velocity. This can be determined by plotting air velocity against the
distance from the surface for each setup.
Comparisons:
Smooth Plate: Results in a thinner boundary layer and sustains laminar flow over a longer
section.
Rough Plate: Produces a thicker boundary layer with an earlier transition to turbulent flow.
Velocity Profiles:
Effect of Fan Speed:
100% Fan Speed:
Higher airflow generates thinner boundary layers.
Turbulent transition happens earlier due to increased Reynolds numbers.
50% Fan Speed:
Lower airflow results in thicker boundary layers.
Laminar flow persists further along the plate.
Plate Position Comparisons:
Leading Edge (Front Position): The boundary layer is thinnest, and flow remains mostly laminar.
Middle Position: Transition from laminar to turbulent flow begins.
Trailing Edge (Rear Position): The boundary layer is thickest, with turbulence dominating the
flow.
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