New answers tagged fluid-mechanics
2
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Why does flow separation cause an increase in pressure drag?
The flow past a cylinder is a good way to explain what happens with airfoils, too. So let's look what NASA has to show for different levels of viscosity:
Of particular interest is the theoretical ...
- 236k
3
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Why does flow separation cause an increase in pressure drag?
Here is how I have visualized this process in the past but now I am not sure it is correct, and would appreciate comments/corrections.
Using the example above of a cylindrical object with a wake of ...
- 22.1k
3
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Accepted
Why does flow separation cause an increase in pressure drag?
We can have a look at the pressure distribution of the airfoil in attached and separated flow conditions.
This is shown in this image from Fundamentals of Aerodynamics, by John D. Anderson, 6th ...
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3
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Why does flow separation cause an increase in pressure drag?
Why does flow separation cause an increase in pressure drag?
The pressure drag you're talking about is only a portion of the total drag, which originates from the turbulent section of the boundary ...
- 76.5k
5
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Why does flow separation cause an increase in pressure drag?
However, lift is directly linked to drag. So when flow separates, it causes a loss of lift. Wouldn't this also cause a 'loss' of drag?
Lift is not directly related to drag: it is related to induced ...
- 14.6k
2
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Why does flow separation cause an increase in pressure drag?
Appreciate the upvotes but this question deserves a better answer.
The cylinder picture in the question really tells all.
where is the center of low pressure when flow separates?
Not only how low ...
- 20.9k
0
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Can a sonic boom occur in supersonic Mach number?
Therefore, if the air speed is supersonic, the air speed on the wing will still be subsonic
Not really
Only behind a normal shock wave the flow becomes subsonic. Behind an oblique shock wave the ...
- 14.6k
5
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Why does flow separation cause a loss of lift, considering the low pressure is the cause of lift above the wing?
To illustrate the effect of flow separation on lift, consider what the flow outside of the boundary layer "sees" when flowing around the wing. At low angle of attack flow is attached, the ...
- 236k
2
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Accepted
Why does flow separation cause a loss of lift, considering the low pressure is the cause of lift above the wing?
This is an interesting question. Perhaps a good way to break it down:
The local shape of the airfoil forces turning of the air packets
Due to the turning of the air packets, the local pressure ...
- 8,062
3
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Why does flow separation cause a loss of lift, considering the low pressure is the cause of lift above the wing?
So if there is low pressure created in the stalled area of a wing anyways, and all that the flow turning downwards over the wing does is create low pressure, why does lift decrease when flow separates?...
- 14.6k
-1
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Why does flow separation cause a loss of lift, considering the low pressure is the cause of lift above the wing?
Consider the low pressure area in terms of the Bernoulli principle, thinking of the average speed of those molecules as they move from that point normal to the relative wind and the trailing edge. ...
4
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Why does flow separation cause a loss of lift, considering the low pressure is the cause of lift above the wing?
Most of the lift force is from the large package of air that was induced to move down by the wing's passage, not so much from the "suction" of the LP area pulling the wing up. The low ...
- 134k
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Will the air be low pressure above an airfoil going less than Mach 0.3?
Well, we have a chicken and egg issue.
We know by Reynolds number analysis that there is indeed lower pressure above the wing where V is less than Mach 0.3.
Typically at Re = around 500,000 one has an ...
- 20.9k
2
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Accepted
Will the air be low pressure above an airfoil going less than Mach 0.3?
flow only becomes compressible above Mach 0.3... Say you have a plane traveling Mach 0.2. The flow isn't compressible... If the flow is not able to compress, then how does the air accelerate?
There's ...
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