Vibroacoustical Analysis of Flow in Pipes

1995 ◽  
Author(s):  
J. Charley ◽  
F. Carta ◽  
G. Caignaert
Keyword(s):  
Transfer Matrix ◽  
Matrix Model ◽  
Flow Rate ◽  
Fluid Structure Interactions ◽  
Acoustic Intensity ◽  
Fluid Structure

Abstract This paper is concerned with the study of pressure and flow rate fluctuations propagation within ducts. A new transfer matrix model for a pipe taking into account the fluid-structure interactions effects is presented and compared to other formulations; significant gains have been realized. An extension of acoustic intensity technique using four transducers is presented.

Effect of Supraglottal Acoustics On Fluid-Structure Interaction During Human Voice Production

2021 ◽  
Author(s):  
Dariush Bodaghi ◽  
Weili Jiang ◽  
Qian Xue ◽  
Xudong Zheng
Keyword(s):  
Flow Rate ◽  
Vocal Fold ◽  
Splitting Method ◽  
Acoustic Resonance ◽  
Coupled Processes ◽  
Fluid Structure Interactions ◽  
Fluid Structure ◽  
Voice Production ◽  
Acoustic Perturbation ◽  
Human Voice

Abstract A hydrodynamic/acoustic splitting method was used to examine the effect of supraglottal acoustics on fluid-structure interactions during human voice production in a two-dimensional computational model. The accuracy of the method in simulating compressible flows in typical human airway conditions was verified by comparing it to full compressible flow simulations. The method was coupled with a three-mass model of vocal fold lateral motion to simulate fluid-structure interactions during human voice production. By separating the acoustic perturbation components of the airflow, the method allows isolation of the role of supraglottal acoustics in fluid-structure interactions. The results showed that an acoustic resonance between a higher harmonic of the sound source and the first formant of the supraglottal tract occurred during normal human phonation when the fundamental frequency was much lower than the formants. The resonance resulted in acoustic pressure perturbation at the glottis which was of the same order as the incompressible flow pressure and found to affect vocal fold vibrations and glottal flow rate waveform. Specifically, the acoustic perturbation delayed the opening of the glottis, reduced the vertical phase difference of vocal fold vibrations, decreased flow rate and maximum flow deceleration rate at the glottal exit; yet, they had little effect on glottal opening. The results imply that the sound generation in the glottis and acoustic resonance in the supraglottal tract are coupled processes during human voice production and computer modeling of vocal fold vibrations needs to include supraglottal acoustics for accurate predictions.

Fluid-Structure Interactions

2009 ◽  
Author(s):  
Michael Paidoussis ◽  
Stuart Price ◽  
Emmanuel de Langre
Keyword(s):  
Fluid Structure Interactions ◽  
Fluid Structure

Experimental Mixing Parameterization Due to Multiphase Fluid � Structure Interactions

2010 ◽  
Vol 5 (2) ◽  
pp. 1-8
Author(s):  
Ranis N. Ibragimov ◽  
◽  
Akshin S. Bakhtiyarov ◽  
Margaret Snell ◽  
◽  
...  
Keyword(s):  
Fluid Structure Interactions ◽  
Fluid Structure ◽  
Multiphase Fluid

scholarly journals Cross-Flow Tidal Turbines with Highly Flexible Blades—Experimental Flow Field Investigations at Strong Fluid–Structure Interactions

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 797
Author(s):  
Stefan Hoerner ◽  
Iring Kösters ◽  
Laure Vignal ◽  
Olivier Cleynen ◽  
Shokoofeh Abbaszadeh ◽  
...  
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Cross Flow ◽  
Speed Ratio ◽  
Fluid Structure Interactions ◽  
Dimensional Parameter ◽  
Fluid Structure ◽  
Passive Flow Control ◽  
Tidal Turbines ◽  
Tidal Turbine

Oscillating hydrofoils were installed in a water tunnel as a surrogate model for a hydrokinetic cross-flow tidal turbine, enabling the study of the effect of flexible blades on the performance of those devices with high ecological potential. The study focuses on a single tip-speed ratio (equal to 2), the key non-dimensional parameter describing the operating point, and solidity (equal to 1.5), quantifying the robustness of the turbine shape. Both parameters are standard values for cross-flow tidal turbines. Those lead to highly dynamic characteristics in the flow field dominated by dynamic stall. The flow field is investigated at the blade level using high-speed particle image velocimetry measurements. Strong fluid–structure interactions lead to significant structural deformations and highly modified flow fields. The flexibility of the blades is shown to significantly reduce the duration of the periodic stall regime; this observation is achieved through systematic comparison of the flow field, with a quantitative evaluation of the degree of chaotic changes in the wake. In this manner, the study provides insights into the mechanisms of the passive flow control achieved through blade flexibility in cross-flow turbines.

scholarly journals Effect of Subglottic Stenosis on Vocal Fold Vibration and Voice Production Using Fluid–Structure–Acoustics Interaction Simulation

2021 ◽  
Vol 11 (3) ◽  
pp. 1221
Author(s):  
Dariush Bodaghi ◽  
Qian Xue ◽  
Xudong Zheng ◽  
Scott Thomson
Keyword(s):  
Flow Rate ◽  
Vocal Fold ◽  
Flow Resistance ◽  
Signal To Noise Ratio ◽  
Area Ratio ◽  
Subglottic Stenosis ◽  
Fluid Structure ◽  
Voice Production ◽  
Vocal Fold Vibration ◽  
Glottal Flow

An in-house 3D fluid–structure–acoustic interaction numerical solver was employed to investigate the effect of subglottic stenosis (SGS) on dynamics of glottal flow, vocal fold vibration and acoustics during voice production. The investigation focused on two SGS properties, including severity defined as the percentage of area reduction and location. The results show that SGS affects voice production only when its severity is beyond a threshold, which is at 75% for the glottal flow rate and acoustics, and at 90% for the vocal fold vibrations. Beyond the threshold, the flow rate, vocal fold vibration amplitude and vocal efficiency decrease rapidly with SGS severity, while the skewness quotient, vibration frequency, signal-to-noise ratio and vocal intensity decrease slightly, and the open quotient increases slightly. Changing the location of SGS shows no effect on the dynamics. Further analysis reveals that the effect of SGS on the dynamics is primarily due to its effect on the flow resistance in the entire airway, which is found to be related to the area ratio of glottis to SGS. Below the SGS severity of 75%, which corresponds to an area ratio of glottis to SGS of 0.1, changing the SGS severity only causes very small changes in the area ratio; therefore, its effect on the flow resistance and dynamics is very small. Beyond the SGS severity of 75%, increasing the SGS severity, leads to rapid increases of the area ratio, resulting in rapid changes in the flow resistance and dynamics.

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