高レイノルズ数域のプラント内構造物の流れ方向振動の発生機構の解明

• Material Type: 文書・図像類
• Title: 高レイノルズ数域のプラント内構造物の流れ方向振動の発生機構の解明
• Author/Editor: 岡島, 厚; Okajima, Atsushi
• Author Heading: 岡島, 厚; Okajima, Atsushi
• Publication, Distribution, etc.: 金沢大学工学部
• Publication Date: 2002-03
• Publication Date (W3CDTF): 2002-03
• Alternative Title: Study on Flow-Induced In-Line Oscillation of a Structure in the Pipe System of Industrial Plants in the Region of High Reynolds Number
• Periodical title: 平成13(2001)年度 科学研究費補助金 基盤研究(B) 研究成果報告書 = 2001 Fiscal Year Final Research Report
• No. or year of volume/issue: 1999-2001
• Volume: 1999-2001
• Pages: 8p.-
• Text Language Code: jpn
• Subject Heading: 流体関連振動; ブラフボディー; 渦励振; 流れ方向振動; 高レイノルズ数; 減衰質量比; アスペクト比; テーパ比; Flow-induced vibration; In-Line Oscillation; Bluff body; High Reynolds number; Reducedmass damping parameter; Circular cylinder; Aspect ratio; Taperd circular cylinder
• Target Audience: 一般
• Note (General): 工業プラントの配管内センサーに用いられるブラフな断面構造物の後流域は、流れの剥離による複雑な渦構造を呈し、構造物は後流渦によって様々な自励振動現象が生じる。高速増殖炉「もんじゆ」のナトリウム漏洩事故の主な原因であった低流速域で起こった流れ方向振動も自励振動の一つである。本研究は円柱や矩形柱断面柱などの構造物の流れ方向流力振動の発生機構に関し、風洞実験、水槽実験、数値シミュレーションによって、主として両端弾性支持円柱した自由振動試験によって、次のようなことを明らかにした。(1)振動する円柱及び種々な断面比の矩形断面柱周りの流れ(レイノルズ数Re=10^4)をスモーク・ワイヤー法によって可視化し、振動特性と流れパターンの対応を示し、共振流速の1/2を境にして二つの励振域において、それぞれ振動円柱周りの対称渦及び交互渦の鮮明な可視化映像を得た。(2)表面粗さを導入して、臨界域以上の高いレイノルズ数領域の円柱周りの流れを実現して、高レイノルズ数領域の渦励振の様相を明らかにした。臨界域では直角方向振動が極端に抑制されることを見出した。(3)矩形断面柱の流れ方向振動に関しては,断面比が小さく垂直平板に近い場合には交互渦による第二励振域が断面比が大きくなりアフターボディーが長くなると、対称渦を伴う第一励振域が支配的となることを明らかにした。(4)二自由度弾性支持円柱の流れ方向の流力振動時の対称渦及び交互渦の渦構造を数値シミュレーションして、それぞれの後流の三次元構造の様相には、相違があることなどを見出し、2つの励振現象は後流の交互渦の形成強さと密接に関係していることを示した。; Flow-induced vibration of bluff bodies occurs in industrial plants such as nuclear power plants, petroleum/chemical plants and offshore platforms. Usually, a thermocouple and a sensor probe are inserted in the pipe system. If the working fluid is a liquid, such cantilever-shaped structures with extremely small mass ratios may be easily induced by the flow to oscillate. For example, the damage to a thermocouple in the fast breeder reactor "Monju" of the Japan Nuclear Cycle Development Institute in 1995 was caused mainly by a stream wise flow-induced vibration. Vortex shedding from an elastically supported cylinder can cause the cylinder to oscillate in the transverse (cross-flow) and strea mwise (in-line) directions if the damping of the system is small.Flow-induced in-line oscillation of a circular cylinder was studied by free-oscillation tests in a water tunnel and a wind tunnel and also by numerical simulations. In a water tunnel and a wind tunnel, we carried out multiple experimenta l studies where a circular cylinder was elastically supported at both ends and where the cylinder was cantilevered. The structure damping parameter was varied over a wide testing range to evaluate the critical value at which the in-line oscillation response is suppressed, when a cylinder is supported at both ends and cantilevered. Response amplitudes of a circular cylinder have been measured and computed for evaluating the values of the reduced mass-damping parameter of less than 1.0. In the free-oscillation tests, the cylinder models were spring-mounted so as to oscillate as a two-dimensional rigid cylinder in the water and wind tunnels. Two types of excitation phenomena appear at approximately half of the resonance flow velocity. The response amplitudes are sensitive to the reduced mass-damping parameter during the in-line oscillation of the first excitation region with a symmetric vortex street, and the alternate vortices are periodically shed, locking-in with the vibration of the cylinder in the second excitation region. A hysteresis phenomenon is observed to appear in the in-line oscillation of the latter region. A cantilevered circular cylinder with a finite length aspect ratio of 10 was tested for fluid-elastic characteristics of the cylinder, and these characteristics are found to be quite different from those of the two-dimensional cylinder, having only one wide velocity region of excitation. The results measured by experiments in the water tunnel and the wind tunnel, and predicted by numerical simulations are in fair agreement. The results of this study are providing important supporting data for the recent publication "Guideline for Evaluation of Flow-Induced Vibration of a Cylindrical Structure in a Pipe" by the Japan Society of Mechanical Engineers, Standard JSME S012-1998.; 研究課題/領域番号:11450074, 研究期間(年度):1999-2001; 出典：「高レイノルズ数域のプラント内構造物の流れ方向振動の発生機構の解明」研究成果報告書 課題番号11450074 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）) 本文データは著者版報告書より作成
• DOI: 10.24517/00049365
• Access Restrictions: 限定公開
• Related Material: https://kaken.nii.ac.jp/search/?qm=80013689; https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11450074/; https://kaken.nii.ac.jp/report/KAKENHI-PROJECT-11450074/114500742001kenkyu_seika_hokoku_gaiyo/
• Data Provider (Database): 国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）; https://irdb.nii.ac.jp
• Original Data Provider (Database): 金沢大学 : 金沢大学学術情報リポジトリKURA