Voice of the dragon: the rotating corrugated resonator

Silverman, Mark P.; Cushman, G. Mark

doi:10.1088/0143-0807/10/4/010

Cited by 19 publications

(18 citation statements)

References 4 publications

(3 reference statements)

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“…Longitudinal standing waves, which are the acoustic subsystem, act as a band-pass filter and maintain the synchronization in this feedback mechanism. This band-pass filter is the reason for stepwise increase of the whistling frequency at certain flow velocities, which has been pointed out in numerous experimental studies (Binnie 1961;Crawford 1974;Silverman & Cushman 1989;Cadwell 1994;Elliott 2005;Kristiansen & Wiik 2007;Kop'ev et al 2008). Each step corresponds to the resonance frequency of an acoustic mode.…”

Section: Introductionmentioning

confidence: 76%

On the whistling of corrugated pipes: effect of pipe length and flow profile

et al. 2011

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Whistling behaviour of two geometrically periodic systems, namely corrugated pipes and multiple side branch systems, is investigated both experimentally and numerically. Tests are performed on corrugated pipes with various lengths and cavity geometries. Experiments show that the peak-whistling Strouhal number, where the maximum amplitude in pressure fluctuations is registered, is independent of the pipe length. Experimentally, a decrease of the peak-whistling Strouhal number by a factor of two is observed with increasing confinement ratio, i.e. the ratio of pipe diameter to cavity width. A numerical methodology that combines incompressible flow simulations with vortex sound theory is proposed to estimate the acoustic source power in periodic systems. The methodology successfully predicts the Strouhal number ranges of acoustic energy production/absorption and the nonlinear saturation mechanism responsible for the stabilization of the limit cycle oscillation. The methodology predicts peak-whistling Strouhal numbers in agreement with experiments and explains the dependence of the peak-whistling Strouhal number on the confinement ratio. Combined with an energy balance, the proposed methodology is used to estimate the acoustic fluctuation amplitudes.

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Section: Introductionmentioning

confidence: 76%

On the whistling of corrugated pipes: effect of pipe length and flow profile

et al. 2011

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“…Missing fundamental A commonly observed phenomenon in short corrugated segments, e.g., Hummer, is the absence of whistling for the fundamental mode. 3,4,18,26,28,39 As addressed in Sec. III C 5, the flow is probably already turbulent for the velocities where the fundamental mode is expected.…”

Section: Discussionmentioning

confidence: 99%

“…In most of the studies the onset of whistling has been detected at the second acoustic longitudinal mode. 3,4,26 Kristiansen and Wiik 27 have recorded an excited fundamental mode. Elliott 18 obtained the whistling first for the ninth mode.…”

Section: Onset Of the Whistlingmentioning

confidence: 99%

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Aeroacoustics of the swinging corrugated tube: Voice of the Dragon

Nakiboglu

Rudenko

Hirschberg

2012

The Journal of the Acoustical Society of America

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When one swings a short corrugated pipe segment around one's head, it produces a musically interesting whistling sound. As a musical toy it is called a "Hummer" and as a musical instrument, the "Voice of the Dragon." The fluid dynamics aspects of the instrument are addressed, corresponding to the sound generation mechanism. Velocity profile measurements reveal that the turbulent velocity profile developed in a corrugated pipe differs notably from the one of a smooth pipe. This velocity profile appears to have a crucial effect both on the non-dimensional whistling frequency (Strouhal number) and on the amplitude of the pressure fluctuations. Using a numerical model based on incompressible flow simulations and vortex sound theory, excellent predictions of the whistling Strouhal numbers are achieved. The model does not provide an accurate prediction of the amplitude. In the second part of the paper the sound radiation from a Hummer is discussed. The acoustic measurements obtained in a semi-anechoic chamber are compared with a theoretical radiation model. Globally the instrument behaves as a rotating (Leslie) horn. The effects of Doppler shift, wall reflections, bending of the tube, non-constant rotational speed on the observed frequency, and amplitude are discussed.

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“…It is also of direct relevance in the modelling of 'singing pipes', where high-speed gas or liquid flow in corrugated pipes can excite acoustic organ-pipe modes (e.g. Crawford 1974;Silverman & Cushman 1989;Cadwell 1994; see also the discussions by Walker 2007, § 3.39). In each of these problems, a simple point-vortex potential flow model could be useful for exploring some of the important physical processes.…”

Section: Introductionmentioning

confidence: 99%

Vortex-induced chaotic mixing in wavy channels

et al. 2010

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Access to the full text of the published version may require a subscription. Mixing is studied in open-flow channels with conformally mapped wavy-wall profiles, using a point-vortex model in two-dimensional irrotational, incompressible mean flow. Unsteady dynamics of the separation bubble induced by oscillatory motion of point vortices located in the trough region produces chaotic mixing in the Lagrangian sense. Significant mass exchange between passive tracer particles inside and outside of the separation bubble forms an efficient mixing region which evolves in size as the vortex moves in the unsteady potential flow. The dynamics closely resembles that obtained by previous authors from numerical solutions of the unsteady Navier-Stokes equations for oscillatory unidirectional flow in a wavy channel. Of the wavy channels considered, the skew-symmetric form is most efficient at promoting passive mixing. Diffusion via gridless random walks increases lateral particle dispersion significantly at the expense of longitudinal particle dispersion due to the opposing effect of mass exchange at the front and rear of the particle ensemble. Active mixing in the wavy channel reveals that the fractal nature of the unstable manifold plays a crucial role in singular enhancement of productivity. Hyperbolic dynamics dominate over nonhyperbolicity which is restricted to the vortex core region. The model is simple yet qualitatively accurate, making it a potential candidate for the study of a wide range of vortex-induced transport and mixing problems. Rights

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Voice of the dragon: the rotating corrugated resonator

Cited by 19 publications

References 4 publications

On the whistling of corrugated pipes: effect of pipe length and flow profile

On the whistling of corrugated pipes: effect of pipe length and flow profile

Aeroacoustics of the swinging corrugated tube: Voice of the Dragon

Vortex-induced chaotic mixing in wavy channels

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