wing end effects - university of tennesseerbond4/422-ch7.pdf · · 2014-11-18wing end effects...
TRANSCRIPT
1
Chapter 7Incompressible Flow About Wings of
Finite Span
Wing End Effects
Wing Tip Vortex Pressure / Lift Distribution
Lifting Line Theory(Vortex Structure)
Downwash and Induced Drag
2
Elliptic Circulation (lift) Distribution
Circulation Distribution
Wing Planform
Downwash Distribution
Effect of AR on CL and CD (Experimental)
Spanwise Lift Distribution(Odd Fourier Terms)
Linear Model
Theory / Experimental Data(Straight Tapered Wing)
Lift Coefficient Distribution
Note: Peak lift coefficient is notat wing root
3
Effect of Taper Ratio
Note: For a highly tapered wing the max. lift coefficient is at the tip.
Effect of Taper Ratio on Wing Stall
Rectangular, λ = 1.0
Tapered, λ = 0.4
Pointed, λ = 0.0
Panel Methods Modeling Method vs. Experimental
Λc/4 = 45o Λc/4 = - 45o
Vortex Lattice
Source Panel
Surface Potential
Elemental Panels and Vortices Single Element per Spanwise Position (Swept Tapered Wing)
Bound Vortex Location
Control Point Location
4
Vortex / CP Location on Panel Induced Velocity at Point C
Horseshoe Vortex Elements
Sharp Leading Edges
• Flow separates at leading edge and reattaches further back
• This creates a low leading edge suction wing.
F-16
Leading edge flaps can be used to increase leading
edge suction.
5
Delta Wings
Flow spills over the leading edge, separates and forms a strong vortex.
Delta Wings – Potential Flow Lift (Kp)
Delta Wings – Vortex Lift (Kv)
Delta Wings – Lift Coefficient
Note the high αααα values
Delta Wings – Drag (∆CD) XB-70At low subsonic speeds delta wings generate a nose-down
pitching moment.
The Valkyrie uses canards to generate a nose-up moment.