Aerodynamically Generated Acoustic Resonance in a Pipe With Annular Flow Restrictors

Stubos, A.K.; Benocci, C.; Palli, E.; Stoubos, G.K.; Olivari, D.

doi:10.1006/jfls.1999.0226

Cited by 24 publications

(11 citation statements)

References 21 publications

(23 reference statements)

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“…32 and 0.5-0.6 in ramjet and cavity studies sited by Dotson et al 16 ). Stubos et al 18 contribute further related work, suggesting that variation in the propagation speed of vortices is related to baf e dimensions and demonstrating a linear correlation of the ratio of baf e to chamber diameters to the hole-tone frequency. A "locking-in" condition occurs when structural and/or acoustic frequencies alter vortex shedding frequencies from those expected based on Eq.…”

Section: Introductionmentioning

confidence: 90%

“…Rockwell (Lehigh University short course notes) discussed that as the baf e spacing d increases, both the vortex strength and the acoustic disturbance strength diminish, which, respectively, results in reductions in both the induced acoustic disturbance and the vortex strength. Stubos et al 18 show vortex shedding lock-in over a d=B range from 0.55 to 5.5, with maximum pressure amplitudes generated for d=B D 1:2. Thus, lower and upper bounds seem to exist on the dimensionless baf e spacing d=B for which hole-tone generation will occur.…”

Section: Introductionmentioning

confidence: 97%

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Vortex Shedding Induced Sound Inside a Cold-Flow Simulation of Segmented Chamber

Flatau

Moorhem

2003

Journal of Propulsion and Power

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Results are presented from a cold-ow investigation of acoustic responses driven by ow through two annular baf es in a cylindrical cavity, having (approximately) closed-closed end conditions. The interaction of the ow with cavity acoustic resonances was examined for different baf e radii, positions, spacings, and stiffness. Nominal vortex shedding frequencies were found to depend on baf e spacing and radii ( ow velocity), with little sensitivity to baf e stiffness. Vortex shedding lock-in frequencies were very sensitive to acoustic pressures and/or acoustic particle velocities acting on the ow at both the upstream and downstream baf es. Vortex shedding lock-in occurred in conjunctionwith acoustic standing waves formed between the baf es and ends of the test chamber such that either acoustic pressure maxima (closed conditions) occurred at the upstream baf e or acoustic velocity maxima (pressure release or open conditions) occurred at the downstream baf e. High acoustic pressure at the upstream baf e appeared to enhance the strength of the shed vortices, and low acoustic pressure (high acoustic particle velocity) at the downstream baf e appeared to enhance the strength of the acoustic eld radiated on vortex impingement. For most of the two baf e geometries, baf e-to-nozzle acoustic modes were the dominant mechanism responsible for lock-in and strong reinforcement of vortex shedding driven acoustic excitation.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 97%

Vortex Shedding Induced Sound Inside a Cold-Flow Simulation of Segmented Chamber

Flatau

Moorhem

2003

Journal of Propulsion and Power

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“…They include a jet through a system of orifice plates (Hourigan et al, 1990;Stoubos et al 1999), a separated shear layer past a cavity resonator (DeMetz & Farabee, 1977;Elder, 1978;Elder, Farabee & DeMetz, 1982;andNelson et al 1981, 1983), and a separated layer past a resonant side branch in the form of a duct or pipe (Pollack, 1980;Bruggeman et al 1989Bruggeman et al , 1991Kreisels ef al. 1995;Ziada & Biihlmann, 1992;and Ziada & Shine, 1999).…”

Section: Overview Of Flow Tonesmentioning

confidence: 99%

Imaging of the self-excited oscillation of flow past a cavity during generation of a flow tone

Geveci

Oshkai

Rockwell

et al. 2003

Journal of Fluids and Structures

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Flow through a pipeline-cavity system can give rise to pronounced ff ow tones, even when the inflow boundary layer is fully turbulent. Such tones arise from the coupling between the inherent instability of the shear flow past the cavity and a resonant acoustic mode of the system. A technique of high-image-density particle image velocimetry is employed in conjunction with a special test section, which allows effective laser illumination and digital acquisition of patterns of particle images. This approach leads to patterns of velocity, vorticity, streamline topology and hydrodynamic contributions to the acoustic power integral. Comparison of global, instantaneous images with time-and phaseaveraged representations provides insight into the small-scale and large-scale concentrations of vorticity, and their consequences on the topological features of Streamline patterns, as well as the streamwise and transverse projections of the hydrodynamic contribution to the acoustic power integral. Furthermore, these global approaches allow the definition of effective wavelengths and phase speeds of the vortical structures, which can lead to guidance for physical models of the dimensionless frequency of oscillation.

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“…Due to the difficulties of predicting acoustic resonance using analytical or numerical methods, much of the work has been conducted experimentally, similar to the shaker excitations used for modal extraction in structural engineering. A classical approach to establish possible links between observed instabilities and acoustic resonances is based on white-noise excitation of the component under study and the filtering of acoustic resonance frequencies by using loudspeakers [10][11][12][13][14]. In many cases, such experimental simple acoustic characterization may well provide crucial information about flow-induced resonant sound generation during operating conditions [15,16].…”

Section: Introductionmentioning

confidence: 99%

A combined time and frequency domain approach for acoustic resonance prediction

Chassaing

Sayma

Imregun

2008

Journal of Sound and Vibration

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This is the accepted version of the paper.This version of the publication may differ from the final published version.Permanent repository link: http://openaccess.city.ac.uk/7905/ Link to published version: http://dx. AbstractA general time and frequency methodology has been developed to identify acoustic resonance conditions of internal flow configurations. The resonant frequencies and the corresponding acoustic modes are determined by imposing onto the flow a time-dependent excitation at several locations on the boundary. The resulting time-domain responses of the pressure signals, which are computed via an unsteady Favre-Reynolds averaged Navier-Stokes solver, are used to determine the frequency response function matrix of the fluid which can be considered to be a multipleinput multiple-output system. The main test case was selected to be a closed-end cylindrical duct for which the effect of different excitation techniques on the predicted resonant acoustic field is discussed in detail. The last test case deals with the acoustic characterization of a 2-D channel with symmetric bumps and an inlet flow velocity of 17 ms −1 . It is shown that the methodology was suitable for identifying both axial and transverse acoustic modes in a 10 Hz -3 kHz frequency range.

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Aerodynamically Generated Acoustic Resonance in a Pipe With Annular Flow Restrictors

Cited by 24 publications

References 21 publications

Vortex Shedding Induced Sound Inside a Cold-Flow Simulation of Segmented Chamber

Vortex Shedding Induced Sound Inside a Cold-Flow Simulation of Segmented Chamber

Imaging of the self-excited oscillation of flow past a cavity during generation of a flow tone

A combined time and frequency domain approach for acoustic resonance prediction

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