Study on a countermeasure for high level sound generated from boiler tube bank duct using walls made of perforated plate (Grasp critical aperture ratio and influence of cavity volume on suppression effect)

Ishihara, Kunihiko

doi:10.1299/transjsme.16-00456

Cited by 4 publications

(2 citation statements)

References 11 publications

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“…Figure 25 shows the effect of a cavity volume or depth on the sound pressure level in the case of the aperture ratio ϕ = 4% as the typical example of the aperture ratio. Further, Ishihara [28] clarified experimentally the critical and optimum aperture ratios. The results show that the critical aperture ratio is about 0.25%, and the optimum aperture ratio is concluded to be 4%.…”

Section: Results Of Experimentsmentioning

confidence: 96%

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Countermeasure for High Level Sound Generated from Boiler Tube Bank Duct

Mori¹,

Ishihara²

2019

Noise and Vibration Control - From Theory to Practice

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Heat exchangers and boilers are widely used in various plants such as power plants and chemical plants. In the heat exchanger and the boiler, a high level sound is sometimes generated from the tube bank installed in a duct. In tube banks, warm gas flows outside of the tube, and due to the external flow around tube banks, the Karman vortex shedding occurs. At a certain frequency of the Karman vortex shedding that depends on the flow velocity, the resonance phenomenon called the self-sustained tone occurs. The self-sustained tone might cause noise problems in the surroundings, losses due to plant shutdown, etc. For suppression of the self-sustained tone, insertion of baffle plates in the tube bank is generally used. Although the insertion of baffle plates has been adopted for a long time, it is difficult to decide the effective insertion positions. On the other hand, a method using perforated plates has been proposed for the suppression of the self-sustained tones. In this chapter, we review the generation mechanism of the self-sustained tone clarified experimentally and numerically, and the methods for suppressing a self-sustained tone using baffle plates and perforated plates.

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Section: Results Of Experimentsmentioning

confidence: 96%

“…In this section, we describe the experiments performed by Ishihara and Nakaoka [13] and Ishihara [28]. They carried out some experiments to examine the suppression effect of the perforated plates and cavities installed, and confirmed the suppression effect.…”

Section: Setup Of Experimentsmentioning

confidence: 94%

Countermeasure for High Level Sound Generated from Boiler Tube Bank Duct

Mori¹,

Ishihara²

2019

Noise and Vibration Control - From Theory to Practice

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Study on acoustic natural frequency and its mode of one dimensional sound field partitioned by perforated plate

Ishihara

Kudo

Masumoto

et al. 2018

Transactions of the JSME (In Japanese)

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Karman vortex shedding occurs when the gas passes through the duct with tube bank of the heat exchangers, such as gas heaters and boilers. Very high level sound in called "self-sustained tones" occurs due to the interference of the vortex and the sound field in the duct. In general, baffle plates are used to suppress the self-sustained tone. However, it is difficult to use them effectively, because insertion conditions have not been established. Then, perforated plates are installed in both sides of the duct to suppress the self-sustained tones. As a result, it was clarified that the perforated plate could suppress the self-sustained tone as expected. The perforated plates are generally used with a cavity to obtain the suppression effect effectively. However the perforated plates change the acoustic natural frequency of the sound field of the duct. In previous paper, this was not referred. This paper aims to clarify the role of the perforated plates when it changes the acoustic natural frequency of the duct. In this study, one dimensional duct will be used for simplicity and the relationship between the aperture ratio and the acoustic natural frequency will be obtained analytically and experimentally. As a result, it was clarified that the analytical results are in good agreement with the experimental ones and the plates with holes had a role of acoustic damping in calculation of the acoustic natural frequency of the one dimensional sound field like a duct with plates with holes. 熱交換器のダクト内には管群(熱交換を行うため，温水や蒸気などを通す管の集合部)が存在する．この管群と

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Study on acoustic natural frequency of one dimensional sound field partitioned by perforated plate

Ishihara

Kudo

2019

Transactions of the JSME (In Japanese)

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A Perforated plate is used as an acoustic absorption material for compressors and acoustic barriers for roads and railways.There are many studies of the perforated plate from the aspect of the acoustic absorption. In this paper, the effect of set positions of the perforated plate on the acoustic natural frequency is considered with the TMM and the experiment. And the reason why the analytical result due to the TMM and the equation of Melling are in good agreement is clarified. From the analytical and experimental results, it is clarified that the smaller the aperture ratio becomes, the lower the acoustic natural frequency becomes with increasing of the hole length of the perforated plate. And the set position of the perforated plate can control the excitation of an acoustic specific mode. And the TMM is useful for obtaining the acoustic natural frequency, because the imaginary part of the acoustic impedance of an orifice obtained by Melling coincides with the analytical result by the TMM.

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Study on a countermeasure for high level sound generated from boiler tube bank duct using walls made of perforated plate (Grasp critical aperture ratio and influence of cavity volume on suppression effect)

Cited by 4 publications

References 11 publications

Countermeasure for High Level Sound Generated from Boiler Tube Bank Duct

Countermeasure for High Level Sound Generated from Boiler Tube Bank Duct

Study on acoustic natural frequency and its mode of one dimensional sound field partitioned by perforated plate

Study on acoustic natural frequency of one dimensional sound field partitioned by perforated plate

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