2019 Fiscal Year Final Research Report
Improvement of prediction method of acoustic resonance in boiler tube banks using feedback model of vortex intensity
| Project/Area Number |
17K06232
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Dynamics/Control
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| Research Institution | Oita University |
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Principal Investigator |
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | 流体関連振動・騒音 / 音響共鳴現象 / 渦 / 管群 / ボイラ |
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| Outline of Final Research Achievements |
The span wise correlation length and intensity of vortex shedding from in-line tube banks were experimentally investigated. It was easy to generate acoustic resonance of low order transverse mode as the tube pitch ratio in the flow direction increased. As the tube pitch ratio in the flow direction decreased, the acoustic resonance of longitudinal mode occurred. The onset velocity of longitudinal mode were lower than that of transverse mode at the small tube pitch ratios. As the span wise scale of vortex decreased, the peak SPLs decreased, and the onset velocity of each mode of acoustic resonance increased for all acoustic modes. The variation of gap velocity could be predicted by considering the reduction of span wise scale of vortex and the increase of gap velocity kept the peak SPLs. The acoustic absorption performance correlated with the vortex shedding from tube banks for small tube pitch ratio. We have discussed the prediction method of acoustic resonance in tube banks.
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| Free Research Field |
機械力学・制御
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| Academic Significance and Societal Importance of the Research Achievements |
本研究は，ガスタービン用排熱回収ボイラなどにおいて今後も継続して発生する恐れがある気柱共鳴現象によるトラブルの減少に多大に寄与するものである．近年，数値解析技術が急速に発展しているが，管の本数が多い管群内の三次元の流れ場の解析は未だ困難であり，流体・音響・構造が密接に連成した管群音響共鳴現象の正確な発生予測は不可能である．本研究成果は，数値解析の結果の可否を判断するためのベンチマークデータとしても使用できる．
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