Lift and Drag Lecture 7 ME EN 412 Andrew Ning aning@byu.edu - - PDF document

lift and drag
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Lift and Drag Lecture 7 ME EN 412 Andrew Ning aning@byu.edu - - PDF document

Lift and Drag Lecture 7 ME EN 412 Andrew Ning aning@byu.edu Outline Definitions Lift and Drag in Potential Flow Definitions Flat Plate Example Munson 9.5. Assume the following average pressure and shear stress on the surface of the


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Lift and Drag

Lecture 7

ME EN 412 Andrew Ning aning@byu.edu

Outline

Definitions Lift and Drag in Potential Flow

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SLIDE 2

Definitions

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Flat Plate Example

Munson 9.5. Assume the following average pressure and shear stress on the surface of the 1-m-square flat plate. Determine the lift and drag

  • generated. How much does the shear stress

contribute to each? Dynamic Pressure: Pressure coefficient:

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SLIDE 4

Lift and Drag coefficient: Moment coefficient: Center of pressure: Aerodynamic center:

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SLIDE 5

Lift and Drag in Potential Flow D’Almbert’s Paradox

For potential flow, what is the drag around the cylinder? What about around an arbitrarily airfoil?

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SLIDE 6

Circulation Γ =

  • C
  • V · d

s

L A B

Kutta-Joukowski Theorem

  • L′ = ρ∞

V × Γ

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SLIDE 7

Drag in Viscous Fluids

Skin Friction Drag and Pressure Drag