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Cycle-to-cycle flow variations in a square duct with a symmetrically oscillating constriction.
Erica Sherman1, Lori Lambert1, Bethany White1
1Dept. of Mechanical & Materials Eng'g.; University of Nebraska - Lincoln; Lincoln, NE 68588.
Fluid Dynamics Research
|May 28, 2021
Summary
Digital Particle Image Velocimetry (DPIV) measured unsteady internal flows in a duct with oscillating constrictions. Findings advance acoustic modeling of human phonation by analyzing fluid-structure interactions and acoustic source strengths.
Area of Science:
- Fluid dynamics
- Acoustics
- Biomedical engineering
Background:
- Modeling unsteady internal flows is crucial for applications like human phonation.
- Integral control volume analysis offers a quantitative approach to understanding these flows.
- Fluid-structure interactions within constrictions significantly impact flow dynamics.
Purpose of the Study:
- To investigate flow complexities in a duct with oscillating constrictions using Digital Particle Image Velocimetry (DPIV).
- To advance the application of integral control volume analysis for modeling unsteady internal flows.
- To provide quantitative insights into acoustic source strengths and fluid-structure interactions relevant to human phonation.
Main Methods:
- Spatially and temporally resolved DPIV measurements were conducted.
- Experiments utilized a square cross-section duct with computer-controlled oscillating constrictions (rocking and open/close motions).
- Flows were analyzed over a specific Strouhal number range (0.012-0.048) at a fixed Reynolds number (8000).
Main Results:
- Observed flow asymmetries and cycle-to-cycle variations despite nominally 2D and symmetric conditions.
- Quantified dynamics of fluid-structure interactions within the oscillating glottis model.
- Identified contributions to acoustic source strengths through coupled integral conservation and acoustic equations.
Conclusions:
- The study demonstrates the utility of DPIV in characterizing complex unsteady flows in oscillating systems.
- Integral conservation equations, coupled with acoustic equations, provide valuable insights into phonation acoustics.
- Observed flow asymmetries and variations highlight the sensitivity of internal flows to geometric and kinematic parameters.
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