2018 Fiscal Year Final Research Report
Elucidation of mechanism of self-excited Pressure Vibration using an Automatic Pressure-Reducing Valve and fatigue failure of pipeline and establishment of preventive measures
| Project/Area Number |
15K07650
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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 |
Rural environmental engineering/Planning
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| Research Institution | University of Miyazaki |
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Principal Investigator |
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| Project Period (FY) |
2015-04-01 – 2019-03-31
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| Keywords | 減圧弁 / 低圧化パイプライン / 固有振動周期 / 自励振動的圧力脈動 |
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| Outline of Final Research Achievements |
In this study, a waveform of a self-excited pressure vibration that occurs in low-pressure pipeline systems was analyzed using a pressure-reducing valve. This analysis was conducted on the basis of field measurement data that was obtained for the condition in which the pressure-reducing valve is placed in the middle of the pipeline. On obtaining the intrinsic oscillation period from the transfer matrix and the oscillation period of the field measurement waveform from the spectral analysis, it was clarified that the theoretical period of the intrinsic oscillation of the pipeline approximates the shortest oscillation period based on the measurement data and provides an indication of the periodicity of the pipeline. In addition, the efficacy of the installation of the surge tank and air stick for controlling the pressure oscillation was theoretically and experimentally demonstrated. Based on these results, it was proposed that the occurrence of the self-excited pressure vibration.
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| Free Research Field |
農業農村工学
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| Academic Significance and Societal Importance of the Research Achievements |
減圧弁を用いた低圧化パイプラインが普及すると，想定外の減圧弁の自励振動が発生して，設計圧力を超える高圧の圧力脈動が減圧弁上流部に生じ，さらに，これが減衰しないため，耐圧強度に余裕のない弁等の機材が破損するなどの事故が発生している．このように，減圧弁を用いた低圧化システムにおいて，これらの管路トラブルのメカニズムの究明と有効な対策を確立することが求められている．低圧化システムの自励振動的な圧力脈動現象の発生は，減圧弁を挟んだ上下流の管路の固有振動周期に起因することを強く示唆する結果が得られた．その結果に基づいて，管路の固有振動周期を用いた自励振動的圧力脈動発生の可能性評価方法を提案した．
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