Flow Visualization and Acoustic Consequences of the Air Moving Through a Static Model of the Human Larynx

2005 ◽  
Vol 128 (3) ◽  
pp. 380-390 ◽  
Author(s):  
Bogdan R. Kucinschi ◽  
Ronald C. Scherer ◽  
Kenneth J. DeWitt ◽  
Terry T. M. Ng
Keyword(s):  
Flow Visualization ◽  
Flow Structure ◽  
Flow Rate ◽  
Real Life ◽  
Vocal Folds ◽  
Jet Flow ◽  
Scale Model ◽  
Flow Structures ◽  
Human Larynx ◽  
False Vocal

Flow visualization with smoke particles illuminated by a laser sheet was used to obtain a qualitative description of the air flow structures through a dynamically similar 7.5× symmetric static scale model of the human larynx (divergence angle of 10deg, minimal diameter of 0.04cm real life). The acoustic level downstream of the vocal folds was measured by using a condenser microphone. False vocal folds (FVFs) were included. In general, the glottal flow was laminar and bistable. The glottal jet curvature increased with flow rate and decreased with the presence of the FVFs. The glottal exit flow for the lowest flow rate showed a curved jet which remained laminar for all geometries. For the higher flow rates, the jet flow patterns exiting the glottis showed a laminar jet core, transitioning to vortical structures, and leading spatially to turbulent dissipation. This structure was shortened and tightened with an increase in flow rate. The narrow FVF gap lengthened the flow structure and reduced jet curvature via acceleration of the flow. These results suggest that laryngeal flow resistance and the complex jet flow structure exiting the glottis are highly affected by flow rate and the presence of the false vocal folds. Acoustic consequences are discussed in terms of the quadrupole- and dipole-type sound sources due to ordered flow structures.

Flow Visualization and Frequency Characteristics of Velocity Fluctuations of Complex Turbulent Flow in a Short Elbow Piping Under High Reynolds Number Condition

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Hiroyuki Takamura ◽  
Shinji Ebara ◽  
Hidetoshi Hashizume ◽  
Kosuke Aizawa ◽  
Hidemasa Yamano
Keyword(s):  
Reynolds Number ◽  
Flow Visualization ◽  
Flow Separation ◽  
Velocity Fluctuation ◽  
Flow Region ◽  
Frequency Characteristics ◽  
Circumferential Direction ◽  
Scale Model ◽  
Flow Structures ◽  
Separation Region

Flow visualization was performed on a single short elbow piping by means of two-dimensional particle image velocimetry. The piping was designed as a 1/7-scale model of a section of the cold-leg piping of a Japan sodium-cooled fast reactor. This study characterized the periodic motions and flow structures that appeared in and downstream of the elbow and potentially affected flow-induced vibrations. The flow field that related flow separation and frequency characteristics of the flow velocity fluctuation were explored for Reynolds number from 0.3 × 106 to 1.0 × 106, which belonged to the post-critical regime. Experimental results show that flow structures are not strongly dependent on Reynolds number in this range. Frequency analysis for the velocity fluctuation in terms of Strouhal number (St) reveals that there exist not only two kinds of vortices with different shedding periods, but also one periodic flow in the circumferential direction. In the flow separation region, vortices are periodically emitted with St ≈ 0.5, while those with about 1.0 are shed in a shear flow region located between the separation region and the pipe center. Moreover, a periodic motion with St ≈ 0.5 appeared in the circumferential direction in the vicinity near the separation region. These values of St were not strongly dependent on Reynolds number in this study.

Influence of False Vocal Folds Gap on the Glottal Jet Flow

2012 ◽  
Author(s):  
Mehrdad H. Farahani ◽  
John Mousel ◽  
Fariborz Alipour ◽  
Sarah Vigmostad
Keyword(s):  
Vocal Folds ◽  
Jet Flow ◽  
Modern Life ◽  
False Vocal ◽  
Ventricular Folds ◽  
Shape And Size

Despite the large incidence of speech problems in the modern life, our knowledge about the effect of supraglottic laryngeal structures on human phonation is lacking. These structures are mainly consisting of aryepiglottic folds, epiglottis, arytenoids, and false folds (ventricular folds). Shape and size of these structures depends on several factors including race, gender, age, and laryngeal abnormalities.

A Study on the Effect of False Vocal Folds Gap Size on the Self-Sustained Oscillation of True Vocal Folds

2013 ◽  
Author(s):  
Mehrdad H. Farahani ◽  
John Mousel ◽  
Sarah Vigmostad
Keyword(s):  
Vocal Folds ◽  
The Self ◽  
Sustained Oscillation ◽  
Mean Values ◽  
Wide Range ◽  
Human Larynx ◽  
Normal Configuration ◽  
False Vocal ◽  
Ventricular Folds ◽  
Different Levels

Recent studies have shown that the supraglottic structures could alter the aeroacoustics output of the larynx [1–2]. The fist supraglottic tissue above the true vocal folds (TVF) is the false vocal folds (FVF) or ventricular folds. This non-oscillatory part of the human larynx shows a wide range of adductions during the normal phonation. Most previous studies, however, have focused on the effect of normal configuration of the FVFs based on mean values reported for this laryngeal structure. Therefore, the effect of different levels of FVF adduction on oscillation of the TVFs remained uninvestigated.

Intake Flow Structure and Swirl Generation in a Four-Valve Heavy-Duty Diesel Engine

2000 ◽  
Vol 122 (4) ◽  
pp. 570-578 ◽  
Author(s):  
Kern Y. Kang ◽  
Rolf D. Reitz
Keyword(s):  
Diesel Engine ◽  
Flow Visualization ◽  
Flow Structure ◽  
Pollutant Emissions ◽  
Flow Structures ◽  
Heavy Duty ◽  
Flow Measurements ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel ◽  
Intake Flow

Intake flow structure was studied using various port geometries in a four-valve heavy-duty diesel engine. Swirl ratio, LDV measurements of bulk flow and turbulence, and flow visualization experiments were conducted on a steady-state bench rig. In addition to the standard production port, archetypal intake port flows (swirl, anti-swirl and tumble) were created using intake valve shrouds. These flow types are not usually found in heavy-duty engines, which typically employ quiescent combustion chamber designs. However, recent CFD analyses have indicated that intake flow structures can significantly influence engine pollutant emissions (Fuchs and Rutland, 1998). Thus, it was of interest to characterize these flows in a heavy-duty engine. The measured swirl and axial velocity components were analyzed to reveal the swirl and tumble generation mechanisms, and the LDV data compared favorably with the swirl meter results. The flow visualization confirmed the existence of flow recirculation regions under the intake valves also seen in the LDV data. These flow structures help to explain the origins of the overall swirl and tumble flow fields. The results were also compared with available CFD predictions made using the same port configurations. The measured swirl levels were found to agree with the CFD trends. However, in some cases quantitative differences were found, presumably due to the effect of piston motion in the actual engine. These differences need to be accounted for when evaluating port designs from steady-flow measurements, especially in cases with high tumble flow components. [S0742-4795(00)00804-8]

scholarly journals Computational study of false vocal folds effects on unsteady airflows through static models of the human larynx

2015 ◽  
Vol 48 (7) ◽  
pp. 1248-1257 ◽  
Author(s):  
Charles Farbos de Luzan ◽  
Jie Chen ◽  
Mihai Mihaescu ◽  
Sid M. Khosla ◽  
Ephraim Gutmark
Keyword(s):  
Computational Study ◽  
Vocal Folds ◽  
Human Larynx ◽  
Static Models ◽  
False Vocal

PULSE RADIOGRAPHY INVESTIGATION OF LIQUID JET FLOW STRUCTURE IN A NONTRANSPARENT MEDIUM

1993 ◽  
Vol 1 (1) ◽  
pp. 69-73
Author(s):  
V. L. Ovsiannikov ◽  
A. R. Berngardt ◽  
E. I. Pal'chikov
Keyword(s):  
Flow Structure ◽  
Jet Flow ◽  
Liquid Jet

Spontaneous perforation of cervical oesophagus: a rare variant of Boerhaave's syndrome

2009 ◽  
Vol 123 (12) ◽  
pp. 1378-1380 ◽  
Author(s):  
S Mittal ◽  
A Rohatgi ◽  
R P Sutcliffe ◽  
A Botha
Keyword(s):  
Vocal Folds ◽  
Sudden Onset ◽  
Water Soluble ◽  
Uneventful Recovery ◽  
Oesophageal Perforation ◽  
Nasogastric Feeding ◽  
Computed Tomography Scanning ◽  
Difficulty Breathing ◽  
The Right ◽  
False Vocal

AbstractBackground:A 29-year-old man presented with sudden onset of severe pain in his throat, difficulty breathing and a hoarse voice, following an episode of vomiting.Investigations:Initial laboratory tests were normal. The patient underwent fibre-optic nasendoscopy, which demonstrated a haematoma in the piriform fossa. Lateral neck radiography and subsequent computed tomography scanning confirmed a 2 cm, loculated, gas-containing collection at the level of the vallecula in the right posterolateral wall, extending to the false vocal folds and communicating between the right parapharyngeal space and the right carotid sheath. Water-soluble contrast swallow confirmed the diagnosis.Diagnosis:Contained oesophageal perforation.Management:Conservative treatment was adopted involving nil orally, intravenous antibiotics and nasogastric feeding. The patient made an uneventful recovery.

Unsteady Aerodynamics of an Aeroengine Double Swirler Lean Premixing Prevaporizing Burner

2004 ◽  
Vol 128 (1) ◽  
pp. 29-39 ◽  
Author(s):  
Edward Canepa ◽  
Pasquale Di Martino ◽  
Piergiorgio Formosa ◽  
Marina Ubaldi ◽  
Pietro Zunino
Keyword(s):  
Flow Field ◽  
Reynolds Stress ◽  
Large Scale ◽  
Unsteady Aerodynamics ◽  
Scale Model ◽  
Flow Structures ◽  
Laser Doppler Velocimeter ◽  
Formation Mechanisms ◽  
Meridional Plane ◽  
Stress Components

Lean premixing prevaporizing (LPP) burners represent a promising solution for low-emission combustion in aeroengines. Since lean premixed combustion suffers from pressure and heat release fluctuations that can be triggered by unsteady large-scale flow structures, a deep knowledge of flow structures formation mechanisms in complex swirling flows is a necessary step in suppressing combustion instabilities. The present paper describes a detailed investigation of the unsteady aerodynamics of a large-scale model of a double swirler aeroengine LPP burner at isothermal conditions. A three-dimensional (3D) laser Doppler velocimeter and an ensemble-averaging technique have been employed to obtain a detailed time-resolved description of the periodically perturbed flow field at the mixing duct exit and associated Reynolds stress and vorticity distributions. Results show a swirling annular jet with an extended region of reverse flow near to the axis. The flow is dominated by a strong periodic perturbation, which occurs in all the three components of velocity. Radial velocity fluctuations cause important periodic displacement of the jet and the inner separated region in the meridional plane. The flow, as expected, is highly turbulent. The periodic stress components have the same order of magnitude of the Reynolds stress components. As a consequence the flow-mixing process is highly enhanced. Turbulence acts on a large spectrum of fluctuation frequencies, whereas the large-scale motion influences the whole flow field in an ordered way that can be dangerous for stability in reactive conditions.

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