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16100lectre34_cj

# 16100lectre34_cj - i tunnel D D D C C C ∆ = ∞ Specific...

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Three-Dimensional Wall Effects In a freestream, recall that a lifting body can e modeled by a horseshoe vortex: V Consider a rectangular cross-section tunnel: Flow is into page The image system for this looks like: Γ Γ Γ wing y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y y images images images images actual tunnel images images images images y y y y y y y y y y y y y y y y y y Γ

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Three-Dimensional Wall Effects 16.100 2002 2 The effect of these images is: For fixed lift, such that Γ is constant, an upwash exists due to images α is effectively larger i tunnel α + effective AOA of correction due to freestream model in upwash induced by AOA tunnel images Similarly, this creates decrease in induced drag relative to freestream flight: Recall, i tunnel i i i i D D D i L D i L D C C C C C C C + = = Or, since we are interested in the total drag:
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Unformatted text preview: i tunnel D D D C C C ∆ + = ∞ Specific formulas derived in detailed analysis give that: L i C C S ) ( δ = ∆ where area reference = S geometry model & tunnel on depends which factor area sectional-cross tunnel = = C Wright Brothers is an elliptic cross-section with dimensions 10 ft wide by 7 ft high. b B h Three-Dimensional Wall Effects 16.100 2002 3 Define: e b actual trailing vortex b b B b k B h e e 9 . span effective ≈ ≡ ≡ ≡ λ horseshoe model b caused because wing tip trailing vortices are inboard of tips a short distance downstream Values of δ for a wing with uniform loading in a closed elliptical jet K = Effective span/Jet width Boundary Correction Factor , δ...
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16100lectre34_cj - i tunnel D D D C C C ∆ = ∞ Specific...

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