Vorticity shedding and acoustic resonance in tube bundles

AUTOR(ES)
FONTE

Journal of the Brazilian Society of Mechanical Sciences and Engineering

DATA DE PUBLICAÇÃO

2006-06

RESUMO

This paper describes the vorticity shedding excitation in tube bundles and its relation to the acoustic resonance mechanism. These phenomena are investigated by means of velocity and pressure measurements, as well as with the aid of extensive visualization of the unsteady flow structure at the presence and absence of acoustic resonance. Vorticity shedding excitation is shown to be generated by either jet, wake, or shear layer instabilities. The tube layout pattern (in-line or staggered), the spacing ratio, and Reynolds number determine which instability mechanism will prevail, and thereby the relevant Strouhal number for design against vorticity shedding and acoustic resonance excitations. Strouhal number design charts for vortex shedding in tube bundles are presented for a wide range of tube patterns and spacing ratios. Regarding the acoustic resonance mechanism, it is shown that the natural vorticity shedding, which prevails before the onset of resonance, is not always the source exciting acoustic resonance. This is especially the case for in-line tube bundles. Therefore, separate "acoustic" Strouhal number charts must be used when appropriate to design against acoustic resonances. To this end, the most recently developed charts of acoustic Strouhal numbers are provided.

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