Lecture 19 Shadowgraph, Schlieren Method

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Lecture 19 Shadowgraph, Schlieren Method
Laser Speckle Photography
Engr 691, Section 10Mechanical Engineering
UMFall 2003
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Refractive Index in Gas
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Deflection of Light Ray in Gas
Refractive index in compressible flow at certain
time
Quantities can be measured in photographic film
Shadowgraph
Schlieren method
Mach-Zehnder interferometer
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Deflection of Light Ray in Gas
Relations between refractive index and measured
quantities
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Shadowgraph
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Shadowgraph
Uniform illumination
Uniform illumination
Non-uniform illumination
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Shadowgraph
APLLICATION DETACHED SHOCK WAVE
Data from http//www.eng.vt.edu/fluids/msc/gallery
/shocks/
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Shadowgraph
APPLICATION A .308 CALIBER BULLET
Shadowgraph of Winchester .308 caliber bullet
traveling at about 2800 ft/sec, M2.5. Curvature
of the Mach lines generated at the nose
Data from http//www.eng.vt.edu/fluids/msc/gallery
/shocks/
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Shadowgraph
APPLICATION SHOCK WAVES AROUND THE X-15
Classical shock wave pattern around a free-flight
model of the X-15 at M3.5. In the lower half
of the image, the convergence of the downstream
shocks with the main bow shock is clearly seen.
Data from http//www.eng.vt.edu/fluids/msc/gallery
/shocks/
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Schlieren Method
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Schlieren Method
Different configurations of Schlieren system
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Schlieren Method
APPLICATION PENETRATION OF ALUMINUM FOIL BY A
BULLET
Pattern of waves generated as a .222 caliber
bullet passes through a hanging sheet of aluminum
foil. The reflected shock is clearly seen at the
left of the foil. A second spherical shock
surface can be seen on the right side of the
foil. The small disturbances just behind the
shock are bits of the foil ejected at impact.
Data from http//www.eng.vt.edu/fluids/msc/gallery
/shocks/
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Schlieren Method
APPLICATION REFRACTION OF SHOCK WAVES
The schlieren photo at the right reveals the
pattern of waves generated by a .222 caliber
bullet traveling at about Mach 3. The bullet has
just passed through the plume of a candle and the
different densities in the heated plume have
refracted the lower set of shock waves.
Data from http//www.eng.vt.edu/fluids/msc/gallery
/shocks/
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Schlieren Method
Full-Scale Schlieren Images
Heat from space heater, lamp person
Heat Released from Gas Grill
Cold Air Dragged From A Freezer
From http//www.mne.psu.edu/psgdl/FSSPhotoalbum/in
dex1.htm
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Speckle Photography
Two schemes of Speckle pattern formation
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Speckle Photography
Two possible configuration of the system
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Speckle Photography
Two possible configuration of the system
2. Speckle generator between light source and
object
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Speckle Photography
Example of speckle photography system
(U Köpf 1972)
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Speckle Photography
Example of speckle photography system
(Wernekinck and Merzkirch 1986)
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Speckle Photography
Evaluation of speckle photograph
- Correlation-based digital interrogation