Flow field measurements in geometrically realistic larynx models
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Flow field measurements in geometrically-realistic larynx models. Jayrin Farley Research Assistant, Brigham Young University, Dept. of Mechanical Engineering Scott L. Thomson Associate Professor, Brigham Young University, Dept. of Mechanical Engineering

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Flow field measurements in geometrically-realistic larynx models

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Flow field measurements in geometrically realistic larynx models

Flow field measurements in geometrically-realistic larynx models

JayrinFarley

Research Assistant, Brigham Young University, Dept. of Mechanical Engineering

Scott L. Thomson

Associate Professor, Brigham Young University, Dept. of Mechanical Engineering

Visiting Professor, University of Erlangen, Graduate School in Advanced Optical Technologies

9th Pan European Voice Conference

Marseille, France

31 August – 3 September 2011


Background

Background

  • Laryngeal airflow:

    • Provides energy for vocal fold vibration

    • Influences speech sound quality

    • Strongly dependent on larynx geometry

  • Most popular methods of measuring velocity:

    • Hot-wire anemometry

    • Particle image velocimetry (PIV)


Piv and hot wire experiments

PIV and hot-wire experiments

  • Static models

    • Simplified geometry

  • Synthetic driven & self-oscillating models

    • Simplified geometry

  • Excised larynges

    • Supraglottis only, geometric and other limitations

  • Problem with realistic geometry: curved surfaces

  • No studies of sub/intra/supraglottalflow using actual, complex geometries


Present work

Present work

  • Method for measuring flow velocity in models using realistic geometry

  • Working fluid: liquid

  • Current implementation: static model

    • Driven model conceivable


Basis for present work

Basis for present work

  • Nasal cavity airflow studies1

  • Create hollow model of desired geometry

  • Match index of refraction between fluid & model

  • Use PIV to measure velocity within model

    1Hopkins et al., 2000, Experiments in Fluids 29:91-95


Model fabrication

Model fabrication

  • 3D CAD model

  • Water-soluble rapid prototype

  • Seal prototype surface

  • Mount prototype in cube-shaped mold

  • Pour clear silicone around model

  • Let silicone cure

  • Dissolve model using running water

    Final product: Clear cube with airway-shaped cavity

    For details: Farley and Thomson, 2011, JASA 130:EL82-EL86


Working fluid selection

Working fluid selection

  • Cavity has curved surfaces

  • For optical access, need fluid to match silicone index of refraction

  • Use glycerine/water mixture


Working fluid selection1

Working fluid selection

  • Place a grid behind the model

  • Start glycerol/water flowing through model

  • Dilute until grid distortion minimized

Grid behind cube

Silicone cube with air-filled cavity


Working fluid selection2

Working fluid selection

  • Place a grid behind the model

  • Start glycerol/water flowing through model

  • Dilute until grid distortion minimized

Water

55% glycerin, 45% water

Air


Test setup

Test setup


Piv settings

PIV settings

  • Hollow glass spheres

  • 500 image pairs

  • 5 sagittal and 5 frontal planes

  • Interrogation: 16 × 16 window, 50% overlap


Piv settings1

PIV settings

  • Hollow glass spheres

  • 500 image pairs

  • 5 sagittal and 5 frontal planes

  • Interrogation: 16 × 16 window, 50% overlap


Velocity results

Velocity results


Velocity results1

Velocity results


Velocity results2

Velocity results


Counter rotating vortices

Counter-rotating vortices

Clockwise vortex

Counter-clockwise vortex


Velocity results3

Velocity results


Velocity results4

Velocity results


Remarks

Remarks

1. Reynolds # similarity maintained (not Mach #)

2. Static model

Driven conceivable

Self-oscillating not possible

3. Results show 3D PIV is desirable

4. Simultaneous pressure measurements possible


Summary and conclusions

Summary and Conclusions

  • Velocity measured in models with complex geometry

  • Can interrogate anywhere in model

  • Future use to characterize 3D flow field

    • Vortical patterns, turbulence levels

    • Computer model validation


Acknowledgements

Acknowledgements

  • U.S. National Institutes of Health

    • R01 DC009616 (Thomson, PI)


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