Lift and Drag from Pressure Distribution over an Air Foil

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SUMMARY

Calculating lift and drag from pressure distribution over an airfoil is feasible, with lift and induced drag being manageable through established methods. However, determining skin friction and parasitic drag presents challenges due to the complexities of flow dynamics. The pressure distribution can be assessed using static pressure measurements and normals to the airfoil surface, but this approach must consider the directional nature of dynamic pressure and the behavior of the boundary layer. The Navier-Stokes equations serve as the foundation for the most accurate mathematical models in this domain.

PREREQUISITES
  • Understanding of Navier-Stokes equations
  • Knowledge of boundary layer theory
  • Familiarity with pressure measurement techniques
  • Experience with aerodynamic principles
NEXT STEPS
  • Study the application of Navier-Stokes equations in fluid dynamics
  • Research boundary layer behavior and its impact on drag
  • Explore instrumentation methods for measuring pressure distribution over airfoils
  • Investigate computational fluid dynamics (CFD) tools for simulating airflow over airfoils
USEFUL FOR

Aerospace engineers, aerodynamicists, and students studying fluid dynamics who are focused on optimizing airfoil performance and understanding lift and drag calculations.

Triggers12
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Pretty simple question:

Is it possible to completely calculate Lift and Drag from the pressure distribution over an airfoil?

Atm, I have Lift worked out as well as the Induced drag ( correct me if I'm wrong. ) but am having trouble working out how it would be possible to get the skin friction / parasitic drag.

Thanks for your help!
Trigs
 
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Triggers12 said:
Is it possible to completely calculate Lift and Drag from the pressure distribution over an airfoil?
How would you determine the pressure distribution over an airfoil? Perhaps some form of intrumentation, but that would have some effect on the flow. A simplified model could use static pressure distribuition and the normals (line perpendicular) to the sections of surface of a wing, but there are other factors. Static pressure isn't directional, but dynamic pressure and any related changes in momentum of the air are directional. Skin friction is nearly parallel to a wing surface. The shear boundary layer thickens over time, may detach and reattach as it transitions from laminar to turbulent, so that changes the effective air foil shape.

The best mathematical models for lift and drag are usually based on some simplified form of Navier Stokes equations:

http://en.wikipedia.org/wiki/Navier–Stokes_equations
 
Last edited:
rcgldr said:
How would you determine the pressure distributaion over an airfoil? Perhaps some form of intrumentation, but that would have some effect on the flow. A simplified model could use static pressure distribuition and the normals (line perpendicular) to the sections of surface of a wing, but there are other factors. Static pressure isn't directional, but dynamic pressure and any related changes in momentum of the air are directional. Skin friction is nearly parallel to a wing surface. The shear boundary layer thickens over time, may detach and reattach as it transitions from laminar to turbulent, so that changes the effective air foil shape.

The best mathematical models for lift and drag are usually based on some simplified form of Navier Stokes equations:

http://en.wikipedia.org/wiki/Navier–Stokes_equations

Hey thanks for the response,

Trigs
 
Last edited by a moderator:

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