Study on Acoustic Absorbers to Suppress Acoustic Resonance in Tube Bundles of Boiler

Nishida, Eiichi; Miki, Masahiro; Sadaoka, Noriyuki; Hamakawa, Hiromitsu; Fukano, Tohru

doi:10.1299/kikaic.71.3458

Cited by 6 publications

(7 citation statements)

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“…To clarify the characteristics of the vortex shedding phenomena in the no-resonance case, the acoustic resonance generated in this model was suppressed with acoustic absorbers [15,17]. The acoustic absorbers were made of glass wool and covered by panting acrylic plates.…”

Section: Vortex Shedding Characteristicsmentioning

confidence: 99%

Effect of Arrangement of Tube Banks on Acoustic Resonance

Hamakawa¹,

Nakamura²,

Asakura³

et al. 2012

OJFD

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In the present paper the attention is focused on effect of arrangement of tube banks on acoustic resonance which occurred in the two-dimensional model of boiler. We have examined the characteristics of vortex shedding and acoustic resonance generated from in-line and staggered tube banks. At the small tube pitch ratio in in-line tube banks, acoustic resonance of third and fourth mode in the transverse direction occurred. As the tube pitch ratio in the flow direction decreased, the vortex shedding frequency became broad-band. The alternative vortex shed from in-line tube banks. The multiple resonance modes were generated within the broad-band vortex shedding frequency. And the acoustic resonances of lower-order modes occurred at the higher gap velocity. On the other hand, at the small tube pitch ratio in staggered tube banks, acoustic resonance did not occurred, although the vortex shed at the resonance frequency in tube banks. The pressure drop at staggered tube banks was larger than that of in-line tube banks. The symmetric vortices were observed inside staggered tube banks at the small tube pitch ratio.

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Section: Vortex Shedding Characteristicsmentioning

confidence: 99%

Effect of Arrangement of Tube Banks on Acoustic Resonance

Hamakawa¹,

Nakamura²,

Asakura³

et al. 2012

OJFD

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“…Figure 3 shows the structure of the coal firing boiler plant. Here, resonant noise was generated in the super-heater section under certain operating conditions (12) . The acoustic space was approximately 40 m in length, 30 m in width, and 20 m in height.…”

Section: Experimental Apparatus and Proceduresmentioning

confidence: 99%

“…Hereafter, this will be written as (1,4). The other acoustic resonances of 27 and 59 Hz were (1,3) and (7,2) respectively (12) . The solid line implies a Strouhal number S t of 0.26.…”

Section: Acoustic Resonance In Actual Boiler Plantmentioning

confidence: 99%

“…The sound velocity ratios S C were different because the temperature Fig. 4 Resonant frequency as a function of gap velocity in the actual boiler plant (12) difference between the tube bank inlet and outlet in the actual boiler plant was taken into account. The tube pitch ratio of the model was the same as that of the actual plant, but the tube diameter ratio S D was not to scale because of the simplicity of the apparatus structure.…”

Section: Similarity With Two-dimensional Modelmentioning

confidence: 99%

“…The close tube spacing suppresses the formation of large eddies within the tube banks. However, acoustic resonances were generated at the actual boiler plant, which had in-line tube banks with small tube pitch ratios (12) . Therefore, the relationship between vortex shedding in in-line tube banks with small tube pitch ratios and acoustic resonance is still unclear.…”

Section: Introductionmentioning

confidence: 99%

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Acoustic Resonance and Vortex Shedding from Tube Banks of Boiler Plant

Hamakawa

Matsue

Nishida

et al. 2008

JFST

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This paper focuses on the relationship between acoustic resonance and vortex shedding from the tube banks of a boiler plant. We have built a model similar to the actual boiler plant to clarify the characteristics of acoustic resonance phenomena and vortex shedding. The model used in-line tube banks with a small tube pitch ratio. We examined the relationship between the acoustic resonance of the actual plant and that of the model, and measured the sound pressure level, acoustic pressure mode shape, spectrum of velocity fluctuation, and gap velocity. Gap velocity was defined as the mean velocity in the smallest gaps between two neighboring tubes in the transverse direction. As a result, the resonant frequencies and mode shapes of the acoustic resonances in the actual boiler plant agreed well with those in the similar model. We found many peak frequencies in the sound pressure level spectrum when acoustic resonances occurred. The typical Strouhal numbers at the onset velocity of acoustic resonances were about 0.19, 0.26 and 0.52. Periodic velocity fluctuation caused by vortex shedding was observed inside the tube banks without acoustic resonance. The Strouhal number measured for vortex shedding was 0.15. Acoustic resonances of higher-order modes were generated in this plant.

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