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Old 25th Jul 2012, 21:46
  #22 (permalink)  
henra
 
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The funny thing is that both theories (Newton and Bernoulli) are indirectly linked to each other.
Newton assumes that air behind the wing is accelerated downward. If you follow the air movement further downstream at one point the diretion of flow will be longitudinal in line with free stream (vortices aside).
The vertical distance between the TE and this point will a) relate to the vertical component of the mass volume flow (Newton) and b) relate to the horizontal volume flow and thus the acceleration of the air above the wing (Bernoulli).

Edit: It is worth looking at different wing polars to cross check. E.g. NACA4506 vs. 2Rz12.
The former being a very thin profile with cl > 0,3 at Alpha = 0°
The latter being a rather thick profile with cl < 0,05 at Alpha = 0°.

The accleration of the air above the wing does not only depend on the thickness of the profile alone but rather on the entire 'expansion' of the flow also behind the wing itself. And that is where Bernoulli will meet Newton.

Last edited by henra; 25th Jul 2012 at 21:57.
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