Synchronous vortex shedding from aerodynamically isolated side-by-side cylinders imposed by flow-excited resonant acoustic modes

2021 ◽  
Vol 62 (10) ◽  
Author(s):  
Mahmoud Shaaban ◽  
Atef Mohany
Keyword(s):  
Vortex Shedding ◽  
Acoustic Modes

Excitation of acoustic modes in a chamber by vortex shedding

1979 ◽  
Vol 64 (3) ◽  
pp. 455-457 ◽  
Author(s):  
F.E.C. Culick ◽  
K. Magiawala
Keyword(s):  
Vortex Shedding ◽  
Acoustic Modes

Parker-Type Acoustic Resonances in the Return Guide Vane Cascade of a Centrifugal Compressor: Theoretical Modeling and Experimental Verification

2010 ◽  
Author(s):  
Sven Ko¨nig ◽  
Nico Petry
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Vortex Shedding ◽  
Guide Vane ◽  
Experimental Results ◽  
Mode Shapes ◽  
Centrifugal Compressors ◽  
Acoustic Modes ◽  
Trailing Edges ◽  
Acoustic Resonances

The potential of acoustic resonances within vane arrays of turbomachinery has been known since the fundamental investigations of Parker back in the sixties and seventies. In his basic studies on flat plate arrays (and later on for an axial compressor) he could show that vortex shedding from the respective trailing edges may excite acoustic resonances that are localized to the vaned flow region. In principle, such phenomena are conceivable for any kind of turbomachinery; however, no such investigations are publicly available for the centrifugal type. The current investigation is one part of an extended research program to gain a better understanding of excitation and noise generating mechanism in centrifugal compressors, and focuses on Parker-type acoustic resonances within the return guide vane cascade of a high-pressure centrifugal compressor. A simplified model to calculate the respective acoustic eigenfrequencies is presented, and the results are compared with finite element analyses. Furthermore, the calculated mode shapes and frequencies are compared with experimental results. It is shown that for high-pressure centrifugal compressors, according to the nomenclature of Parker, acoustic modes of the α, β, γ, and δ type exist over a wide operating range within the return guide vane cascade. For engine representative Reynolds numbers, the experimental results indicate that the vortex shedding frequencies from the vane trailing edges cannot be characterized by a definite Strouhal number; the excitation of the Parker-type acoustic modes is mostly broadband due to the flow turbulence. No lock-in phenomenon between vortex shedding and acoustic modes takes place, and the amplitudes of the acoustic resonances are too small to cause machines failures or excessive noise levels.

Further Evidence for Acoustic Resonance in Full Size Steam Generator and Tubular Heat Exchanger Tube Banks

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Frantisek L. Eisinger ◽  
Robert E. Sullivan
Keyword(s):  
Heat Exchanger ◽  
Steam Generator ◽  
Vortex Shedding ◽  
Acoustic Resonance ◽  
Heat Exchanger Tube ◽  
Tube Bank ◽  
Tubular Heat Exchanger ◽  
Acoustic Modes ◽  
Tube Banks ◽  
Exchanger Tube

Acoustic resonance or acoustic vibration, which develops in flow channels containing a tube bank, is caused by vortex shedding generated by crossflow over the tube bank. Transverse acoustic modes are excited, which are perpendicular to the direction of flow and of the tube axes. For the excitation of the acoustic modes resulting in acoustic resonance, two conditions must be met: (a) The frequency of vortex shedding must coincide with the frequency of the particular acoustic mode to be excited, and (b) there must be sufficient energy available to initiate the vibration. If the frequency coincidence is not satisfied or if the excitation energy is insufficient, the acoustic resonance will not be possible. It is important to define the criteria, which need to be met for the initiation of the acoustic resonance. In this paper, new criteria are developed on the basis of the acoustic particle velocity for the onset of acoustic resonance in steam generator and tubular heat exchanger tube banks.

Coupling Between Internal Vortex Shedding and the Axial Acoustic Modes in a Choked Duct Flow: New Experiments

2000 ◽  
Author(s):  
Eric L. Petersen ◽  
John W. Murdock
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Longitudinal Mode ◽  
Flow Chamber ◽  
Acoustic Mode ◽  
Duct Flow ◽  
Pressure Oscillations ◽  
Longitudinal Acoustic ◽  
Acoustic Modes ◽  
Plate Spacing

Abstract Experiments on vortex shedding within a choked duct and its coupling with the duct’s longitudinal acoustic modes are reported. The vortex shedding and impingement mechanism was produced by a pair of concentric orifice plates placed within the duct. The results of the experiments demonstrate that the frequencies and strengths of the measured acoustic tones depend on the flow velocity, Reynolds number, orifice size, and orifice spacing. A standing wave was produced when the orifice-pair tone was near a longitudinal acoustic mode of the chamber. The oscillation frequency increased slightly with increasing Reynolds number but usually remained within 2-3% of a chamber longitudinal mode. Dual tones and abrupt frequency shifts in singular tones were observed for changes in Reynolds number and/or plate-to-plate spacing. The results of these experiments are part of an ongoing study to better understand the fundamental mechanisms of vortex-induced pressure oscillations within a flow chamber.

Parker-Type Acoustic Resonances in the Return Guide Vane Cascade of a Centrifugal Compressor – Theoretical Modeling and Experimental Verification

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Sven König ◽  
Nico Petry
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Vortex Shedding ◽  
Guide Vane ◽  
Experimental Results ◽  
Simplified Model ◽  
Centrifugal Compressors ◽  
Acoustic Modes ◽  
Trailing Edges ◽  
Acoustic Resonances

The potential of acoustic resonances within vane arrays of turbomachinery has been known since the fundamental investigations of Parker back in the sixties and seventies. In his basic studies on flat plate arrays (and later on for an axial compressor) he could show that vortex shedding from the respective trailing edges may excite acoustic resonances that are localized to the vaned flow region. In principle, such phenomena are conceivable for any kind of turbomachinery; however, no such investigations are publicly available for the centrifugal type. The current investigation is one part of an extended research program to gain a better understanding of excitation and noise generating mechanism in centrifugal compressors, and focuses on Parker-type acoustic resonances within the return guide vane cascade of a high-pressure centrifugal compressor. A simplified model to calculate the respective acoustic eigenfrequencies is presented, and the results are compared with finite element analyses. Furthermore, the calculated mode shapes and frequencies are compared with experimental results. It is shown that for high-pressure centrifugal compressors, according to the nomenclature of Parker, acoustic modes of the α, β, γ, and δ type exist over a wide operating range within the return guide vane cascade. For engine representative Reynolds numbers, the experimental results indicate that the vortex shedding frequencies from the vane trailing edges cannot be characterized by a definite Strouhal number; the excitation of the Parker-type acoustic modes is mostly broadband due to the flow turbulence. No lock-in phenomenon between vortex shedding and acoustic modes takes place, and the amplitudes of the acoustic resonances are too small to cause machines failures or excessive noise levels. The simplified model presented in the current paper has been successfully validated for the return guide vane cascade of a centrifugal compressor but can also be applied for arbitrary blade and vane arrays, given that the chord-to-pitch ratio is sufficiently high. With this model, frequency components in measured pressure signals, that were left unexplained in the past, can be easily inspected for possible Parker-type resonances.

On a Nonlinear Dispersion Effect of Geodesic Acoustic Modes

2013 ◽  
Vol 8 (0) ◽  
pp. 1403010-1403010 ◽  
Author(s):  
Makoto SASAKI ◽  
Kimitaka ITOH ◽  
Naohiro KASUYA ◽  
Klaus HALLATSCHEK ◽  
Sanae-I. ITOH
Keyword(s):  
Nonlinear Dispersion ◽  
Dispersion Effect ◽  
Acoustic Modes

Evolution of unstable system.

2015 ◽  
Vol 9 (3) ◽  
pp. 2487-2502 ◽  
Author(s):  
Igor V. Lebed
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Stokes Flow ◽  
Stable Solution ◽  
The State ◽  
Unstable System ◽  
Unstable Flow ◽  
Unstable Solutions ◽  
Vortex Shedding Modes ◽  
Hydrodynamics Equations

Scenario of appearance and development of instability in problem of a flow around a solid sphere at rest is discussed. The scenario was created by solutions to the multimoment hydrodynamics equations, which were applied to investigate the unstable phenomena. These solutions allow interpreting Stokes flow, periodic pulsations of the recirculating zone in the wake behind the sphere, the phenomenon of vortex shedding observed experimentally. In accordance with the scenario, system loses its stability when entropy outflow through surface confining the system cannot be compensated by entropy produced within the system. The system does not find a new stable position after losing its stability, that is, the system remains further unstable. As Reynolds number grows, one unstable flow regime is replaced by another. The replacement is governed tendency of the system to discover fastest path to depart from the state of statistical equilibrium. This striving, however, does not lead the system to disintegration. Periodically, reverse solutions to the multimoment hydrodynamics equations change the nature of evolution and guide the unstable system in a highly unlikely direction. In case of unstable system, unlikely path meets the direction of approaching the state of statistical equilibrium. Such behavior of the system contradicts the scenario created by solutions to the classic hydrodynamics equations. Unstable solutions to the classic hydrodynamics equations are not fairly prolonged along time to interpret experiment. Stable solutions satisfactorily reproduce all observed stable medium states. As Reynolds number grows one stable solution is replaced by another. They are, however, incapable of reproducing any of unstable regimes recorded experimentally. In particular, stable solutions to the classic hydrodynamics equations cannot put anything in correspondence to any of observed vortex shedding modes. In accordance with our interpretation, the reason for this isthe classic hydrodynamics equations themselves.

Some modeling issues on trailing-edge vortex shedding

AIAA Journal ◽  
2001 ◽  
Vol 39 ◽  
pp. 787-793
Author(s):  
Wei Ning ◽  
Li He
Keyword(s):  
Vortex Shedding ◽  
Trailing Edge ◽  
Edge Vortex
Sign in / Sign up

Export Citation Format

Share Document