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Purdue University - School of Aeronautics and Astronautics

AAE 520 Experimental Aerodynamics

Optical Techniques for Flow

Visualization Shadowgraph

Schlieren

Interferometer

All depend of the fact that the speed of light and therefore the

index of refraction varies with the density.

The index of refraction is approximately

airfor000292.

1!

=

+==

ref

2

2

2

2

yx

+

edge"nifelar toperpendic#gradientsy

7/25/2019 Optical Flow Visualization

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Purdue University - School of Aeronautics and Astronautics

AAE 520 Experimental Aerodynamics

Shadowgraph

$oint

So#rce

of light

%iewingScreen

&low

deflection

Shoc"s appear asa dar" line followed

'y a light line

7/25/2019 Optical Flow Visualization

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Purdue University - School of Aeronautics and Astronautics

AAE 520 Experimental Aerodynamics

Shadowgraph

7/25/2019 Optical Flow Visualization

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Purdue University - School of Aeronautics and Astronautics

AAE 520 Experimental Aerodynamics

7/25/2019 Optical Flow Visualization

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Purdue University - School of Aeronautics and Astronautics

AAE 520 Experimental Aerodynamics

Schlieren (ptics

)ight

So#rceTest

Section

Image

of

so#rce

Image

of

Test

Section

*as"

!"nife edge

a

'

c

d

a+

'+

c+

d+

,nife

edge

Image-isplaced

Image

,nife edge intercepts part of so#rce image

-ensity gradient ca#ses displacementof so#rce image

olor Schlieren #ses a color in

place of "nife edge

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Purdue University - School of Aeronautics and Astronautics

AAE 520 Experimental Aerodynamics

/folded Schlieren sing *irrors

amera

,nife

edge

)ight

So#rce

Test Section

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Purdue University - School of Aeronautics and Astronautics

AAE 520 Experimental Aerodynamics

olor Schlieren

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Purdue University - School of Aeronautics and Astronautics

AAE 520 Experimental Aerodynamics

Schlieren for &light Test

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Purdue University - School of Aeronautics and Astronautics

AAE 520 Experimental Aerodynamics

*ach/ender Interferometer

Test Section

)ightSo#rce eamsplitter

eamsplitter

*irror

*irror

Image

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Purdue University - School of Aeronautics and Astronautics

AAE 520 Experimental Aerodynamics