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Is airflow ever laminar in the boundary layer, near the wing leading edge?

In still air every boundary layer starts laminar. How soon it transitions to a turbulent boundary layer depends on: the local Reynolds number, the pressure gradient, wing sweep and disturbances like ...
• 234k

Is airflow ever laminar in the boundary layer, near the wing leading edge?

Reynolds number is basically the ratio between the viscous and inertial forces acting on the system. At low Reynolds numbers, the viscous force is dominant compared to the inertial force and it is the ...
• 100k
Accepted

• 156

Why don't we simulate similarity parameters simultaneously in the same wind tunnel?

It is extremely expensive to build a wind tunnel that can be both pressurized and handle high-velocity flow. Such large-section wind tunnels do exist, but to maintain high pressure during a test run ...
• 21.3k

Is the Reynolds number the same for both the airfoil and wing? If not, why/how does it change?

From the equation that defines it, you can see that its value depends on some properties of the fluid (air), the speed that an object moves through the fluid, and the length of the object. Nothing ...
• 12.1k

What chord should I use to calculate Reynolds number?

Depends on what you are trying to accomplish. If you are comparing different aircraft, it probably doesn't matter as long as you always do it the same way. If you are designing a wing, the exposed ...
• 20.7k

What chord should I use to calculate Reynolds number?

Reynolds number is a variable parameter. There are multiple definition and you can use one of the two MAC, the important thing is that you specify the reference of your calculation. Usually between ...
• 491
1 vote

Wind turbine airfoil on low Reynolds number aircraft

Do not take the origin of an airfoil as a criterium for its selection. Judge it purely on its merits for the intended purpose. If a wind turbine airfoil gives you better L/D than any other, use it. ...
• 234k
1 vote

Why does a turbulent boundary layer cause more friction drag than a laminar boundary layer?

The basic reason is that the energy to create the turbulence comes in the first place from the forward motion of the aircraft or air vehicle.
• 1,159
1 vote

At which point in scale reduction do slats and flaps become unnecessary?

Putting slats and flaps on a 10 cm model is extreme, but would add a touch of realism for the serious hobbyist. At which point in scale do slats and flaps become unnecessary? We turn to the lift ...
• 20.6k
1 vote

Turbulent flows over 6 series airfoils

Flow at the forward stagnation point of an airfoil is laminar, because the local velocity will be zero. The boundary layer originating form the stagnation point will usually not remain laminar for ...

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