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

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

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
counter rotating vortices
Counter-rotating vortices

Clockwise vortex

Counter-clockwise vortex

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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