Imaging Techniques for Flow and Motion Measurement

Engr 699, Section 81

Instructor: Lichuan Gui

Spring Semester 2011

Tuesdays and Wednesdays 2:00-3:15pm

NCPA class room #1128

Class material available at http://lcgui.net/index_files/Page946.html

EDPIV software available at http://edpiv.com

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Imaging Techniques for Flow and Motion Measurement

Lecture 1

Lichuan Gui

University of Mississippi

2011

Fluid Flow Measurement Methods Fluid Flow Measurement Methods

OverviewOverview

DiscussionDiscussion• Why do fluid flows need to be measured?

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DiscussionDiscussion• What variables need to be measured?

– Velocity– Pressure– Temperature– Density– ?

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– Velocity:

• U-tube manometer

• Pitot probe

• Hot wire/film anemometer (HW/ HF)

• Laser Doppler velocimetry/anemometry (LDV /LDA)

• Sonic anemometer

– Pressure: pressure sensors

– Temperature: temperature sensors

– Density: reduced from P, T etc.

DiscussionDiscussion• Non-imaging measurement techniques:

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• Velocity measurement using U-tube manometer

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PPcV

Non-imaging TechniquesNon-imaging Techniques

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- Calibration required to determine coefficient “c”

• Velocity measurement using pitot probes

2-hole pitot probe (1D)

3-hole pitot probe (2D)

5-hole pitot probe (3D)

Non-imaging TechniquesNon-imaging Techniques

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• Velocity measurement using HW & HF

Non-imaging TechniquesNon-imaging Techniques

Hot wire Hot filmHot film

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• Velocity measurement using HW & HF

Non-imaging TechniquesNon-imaging Techniques

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Energy balance Electric resistance Heat convection coefficient

Flow velocity

- Different systems: CCA, CVA, CTA - Calibration required

• Laser Doppler Velocimetry/Anemometry

Non-imaging TechniquesNon-imaging Techniques

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Non-imaging TechniquesNon-imaging Techniques• Summary of the velocimetries

– Pitot proble, HW & HF

• Point-by-point measurement

• Intrusive

• Calibration required

– LDV (LDA)

• Point-by-point measurement

• Non-intrudsive

• No calibration

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Imaging TechniquesImaging Techniques• Three groups of flow visualization methods

– Foreign material added to the fluid flow

– Optical methods sensitive to refraction index changes

– Foreign energy (e.g. heat or electric discharge) added to the fluid flow

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Imaging TechniquesImaging Techniques• Visualization of flow direction

– Example: Dye lines in water flow

Vortex flow behind a yawed cylinder visualized with mixture of ink, milk and alcohole

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Imaging TechniquesImaging Techniques• Visualization of flow direction

– Example: Smoke lines in air flow

Smoke lines around an airfoil model in a wind-tunnel

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Imaging TechniquesImaging Techniques• Visualization of flow direction

– Example: Tuft Screen

Trailing vortices behind an inclined delta-wing as visualized by a tuft screen

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Imaging TechniquesImaging Techniques• Velocity measurement with tracers

– Example: Hydrogen-bubble technique

Consecutive rows of hydrogen bubbles indicatingVelocity profiles a flat plat boundary layer

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Imaging TechniquesImaging Techniques• Velocity measurement with tracers

– Example: Small particles

Stroboscopic illumination of oil drop in laminar pipe flow

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Imaging TechniquesImaging Techniques• Optical methods for compressed flows

– Shadowgraph

Shadowgraph of a sphere flying at M=1.7

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Imaging TechniquesImaging Techniques• Optical methods for compressed flows

– Schlieren Method

Schlieren photograph around a sphere flying at hypersonic speed

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Imaging TechniquesImaging Techniques• Other methods

– X-ray & Echo PIV

– Molecular Tagging Velocimetry (Seedless velocimetry)

– Laser Speckle Photography

– Temperature measurement with particle Brownian motion

– More

• Summary– Full-field measurement (2D & 3D)

– Non-intrusive

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