Module 6 - Vortex Panel Method Flashcards

1
Q

Where are vortex panels placed in the vortex panel method?

A

Surface of the aerofoil

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2
Q

What is the basic implementation of vortex panel method?

A

Panels that are straight lines are placed on the surface of the aerofoil, each having different lengths and a unique but constant value for the vortex strength per unit length

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3
Q

What overconstrains the vortex panel method?

A

Applying the Kutta condition

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4
Q

How is the set of equations being over-determined dealt with in vortex panel method?

A

Remove one panel equation from the solution

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5
Q

What is the local value of the vortex strength per unit length equal to?

A

Local velocity tangential to surface of aerofoil

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6
Q

What condition on the velocity is set at each control point on the aerofoil surface is satisfied?

A

The normal component of the velocity (including free stream component and induced velocity) is zero to ensure aerofoil surface is a streamline

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7
Q

How is the pressure distribution determined using the vortex panel method?

A

Bernoulli’s equation

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8
Q

What choices affect the accuracy of a vortex panel solution?

A
  1. Panelling (density, number, lengths)
  2. Which panel is removed
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9
Q

How can you use the inviscid vortex panel code to determine the moment at c/4 given the moment at LE?

A

Aerodynamic centre is where moment independent of alpha. For many aerofoils it is close to c/4. We can use eq4.71 with the lift curve slope a0 and moment curve slope m0 in the linear region
Could also compute moment coefficient about position x and look for location where moment independent of angle of attack

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10
Q

What are the main additions of XFOIL?

A
  • A viscous solver, allowing boundary layers to be resolved and flow separation to be computed
  • Set the boundary layer transition point
  • Compressibility effects
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