Effects of air‐jet angle and other jet characteristics on the spectral features of a jet‐driven Helmholtz resonator

Open- and closed-toe voicing of flue organ pipes constitute two opposite extremes of possible ways todetermine the air-jet flow rate through the flue. The latter method offers more voicing control parametersand thus more flexibility, at the expense of a necessary pressure loss at the toe hole. Another differencebetween both cases arises from different air-jet characteristics, such as velocity profile, Re number, flowmomentum or aspect ratio, the latter influencing jet instability. Furthermore, for closed-toe voicing, the flowfield in the pipe foot is modified by an axisymmetric air jet created through the highly constricted toe hole.Velocity measurements on air jets, pressure measurements in the pipe foot are presented, compared anddiscussed for both voicing methods. The ratio of flue to toe hole area is shown to be the sole pipeparameter to entirely determine the jet velocity and can be useful to quantitatively characterize flue and toehole voicing. Open-toe voicing turns out to be the more delicate and low-pressure only method becauseany modification of the flue has consequences on all aspects of the pipe operation, whereas the closed-toemethod, in connection with higher pressures and with active involvement of cut-up adjustment, allows someseparation between sound timbre and power regulation.

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An anharmonic oscillator model for a Helmholtz resonator excited by an air jet.

The Journal of the Acoustical Society of America ◽

10.1121/1.402162 ◽

1991 ◽

Vol 90 (4) ◽

pp. 2352-2352

Author(s):

James P. Cottingham ◽

Jennifer L. Wiersma

Keyword(s):

Anharmonic Oscillator ◽

Helmholtz Resonator ◽

Oscillator Model ◽

Air Jet

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The physiology of oral whistling: a combined radiographic and MRI analysis

Journal of Applied Physiology ◽

10.1152/japplphysiol.00902.2016 ◽

2018 ◽

Vol 124 (1) ◽

pp. 34-39 ◽

Cited By ~ 4

Author(s):

Alba Azola ◽

Jeffrey Palmer ◽

Rachel Mulheren ◽

Riccardo Hofer ◽

Florian Fischmeister ◽

...

Keyword(s):

High Frequency ◽

Vocal Tract ◽

Resonant Cavity ◽

Helmholtz Resonator ◽

Theoretical Models ◽

Experimental Models ◽

Air Jet ◽

Tongue Position ◽

Buccal Space ◽

Opening And Closing

The fluid mechanics of whistling involve the instability of an air jet, resultant vortex rings, and the interaction of these rings with rigid boundaries (see http://www.canal-u.tv/video/cerimes/etude_radiocinematographique_d_un_siffleur_turc_de_kuskoy.13056 and Meyer J. Whistled Languages. Berlin, Germany: Springer, 2015, p. 74–774). Experimental models support the hypothesis that the sound in human whistling is generated by a Helmholtz resonator, suggesting that the oral cavity acts as a resonant chamber bounded by two orifices, posteriorly by raising the tongue to the hard palate, and anteriorly by pursed lips (Henrywood RH, Agarwal A. Phys Fluids 25: 107101, 2013). However, the detailed anatomical changes in the vocal tract and their relation to the frequencies generated have not been described in the literature. In this study, videofluoroscopic and simultaneous audio recordings were made of subjects whistling with the bilabial (i.e., “puckered lip”) technique. One whistling subject was also recorded, using magnetic resonance imaging. As predicted by theory, the frequency of sound generated decreased as the size of the resonant cavity increased; this relationship was preserved throughout various whistling tasks and was consistent across subjects. Changes in the size of the resonant cavity were primarily modulated by tongue position rather than jaw opening and closing. Additionally, when high-frequency notes were produced, lateral chambers formed in the buccal space. These results provide the first dynamic anatomical evidence concerning the acoustic production of human whistling. NEW & NOTEWORTHY We establish a new and much firmer quantitative and physiological footing to current theoretical models on human whistling. We also document a novel lateral airflow mechanism used by both of our participants to produce high-frequency notes.

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Self-sustained oscillation of a jet impinging upon a Helmholtz resonator

Journal of Fluid Mechanics ◽

10.1017/s0022112087001447 ◽

1987 ◽

Vol 179 ◽

pp. 77-103 ◽

Cited By ~ 13

Author(s):

W. M. Jungowski ◽

G. Grabitz

Keyword(s):

Helmholtz Resonator ◽

Sustained Oscillation ◽

Flow Oscillation ◽

Velocity Measurements ◽

Fluctuating Pressure ◽

Air Jet ◽

Oscillation Mechanism ◽

Large Pressure ◽

Detached Shock Wave ◽

Pressure And Velocity Measurements

A planar, sonic, underexpanded air jet induced strong and self-sustained flow oscillation. The jet was bounded by two parallel walls extending between the nozzle and the Helmholtz resonator opposite. This oscillation was characterized by large pressure amplitudes in the resonator and periodic displacement of a detached shock wave. The observed phenomena were in some measure similar to those occurring with Hartmann-Sprenger tubes. Based on the experimental results, including Mach-Zehnder interferograms and fluctuating pressure and velocity measurements, the properties of the oscillation have been described and a model for theoretical analysis has been established. Experimental and numerical investigations have made possible a description of the oscillation mechanism, which is of the relaxation type.

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Wall air–jet characteristics and airflow patterns within a slot ventilated enclosure

International Journal of Thermal Sciences ◽

10.1016/s1290-0729(03)00037-1 ◽

2003 ◽

Vol 42 (7) ◽

pp. 703-711 ◽

Cited By ~ 34

Author(s):

Jean Moureh ◽

Denis Flick

Keyword(s):

Air Jet ◽

Jet Characteristics

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Excitation of a Helmholtz resonator by an air jet

The Journal of the Acoustical Society of America ◽

10.1121/1.399698 ◽

1990 ◽

Vol 88 (3) ◽

pp. 1211-1221 ◽

Cited By ~ 6

Author(s):

Roset Khosropour ◽

Peter Millet

Keyword(s):

Helmholtz Resonator ◽

Air Jet

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Application of Pressure and Temperature Sensitive Paints for Study of Heat Transfer to a Circular Impinging Air Jet

Heat Transfer, Part A ◽

10.1115/imece2005-79214 ◽

2005 ◽

Author(s):

Quan Liu ◽

A. K. Sleiti ◽

J. S. Kapat

Keyword(s):

Heat Transfer ◽

Local Heat Transfer ◽

Target Surface ◽

Local Heat ◽

Surface Flow ◽

Temperature Sensitive ◽

Number Range ◽

Air Jet ◽

Jet Characteristics ◽

Second Peak

Experimental and computational studies are performed to study pressure and temperature distributions and flow patterns on impingement target surface subject to a single impinging air jet from a plenum. The experiments cover a range of jet-to- target plate distance, Z/D, from 1.5 to 12 for Reynolds number range from 5000 to 60000. The main objective is to investigate the optimal jet-to-target distance (Z/D) for stagnation point heat transfer and location of second peak of local heat transfer at small Z/D value of 1.5. Pressure and temperature sensitive paints measurements techniques are implemented to obtain the distribution of pressure and temperature on target surface. Flow visualization test has also been performed using surface oil and smoke technique to obtain the streamline distribution over the impinged surface and to qualitative study jet characteristics. The optimal (Z/D) is found to be 4.8 and second peak location for Z/D of 1.5 is at radial location (r/D) of 1.8. Comparison of average Nu with correlation from open literature, shows agreement to within experimental uncertainty for Z/D=5, while for Z/D=1.5 a 23% difference is found. Experimental results are compared to computational (CFD) prediction using Realizable κ-ε turbulence model.

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