配管内気液二相流中における円柱状構造物の流力振動予測と設計評価ガイドラインの開発

• Material Type: 文書・図像類
• Title: 配管内気液二相流中における円柱状構造物の流力振動予測と設計評価ガイドラインの開発
• 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: Prediction and Guideline for Evaluation of Flow-Induced In-Line Oscillation of a Cylindrical Structure in the Bubbly Flow of the Pipe System
• 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: 7p.-
• 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; 気液二相流; 減衰質量比; アスペクト比; テーパ比; Flow-induced vibration; In-Line Oscillation; Circular cylinder; Bubbly flow; Reduced mass damping parameter; Water tunnel; Aspect ratio; Taperd circular cylinder
• Target Audience: 一般
• Note (General): 「配管内円柱状構造物の流力振動評価指針」のガイドラインをさらに発展させ、正確度の高い、複雑な流れにも適応する気液二相流中における円柱状構造物の流力振動予測と設計評価ガイドラインの開発を行う。まず、実際のプラントン配管に近い、作動流体として水を用いた回流式水槽試験装置で円柱構造物の詳細な流れ方向振動実験を系統的に行い、特に実際の温度計に近い形状の片持ち弾性支持の有限スパン長さの円柱模型を用いて、換算質量減衰係数やテーパ比の影響について調べた。その結果、二次元円柱の応答振幅は共振流速の112を境にして二つの励振域が存在するのに対し、片持ち有限スパン長さ円柱では一つの比較的広い流速範囲の励振域が生じ、振幅の減衰率は二次元円柱の場合の第一励振域におけるよりも小さく、現象は交互渦の形成強さと密接に関連していることを示した。試験結果から、有限スパン長さ円柱で片持ち弾性支持の場合には、米国機械学会基準では基準として不十分なケースが生ずることがあるが、日本機械学会流力振動評価指針(1998年制定)は、この場合でも十分適用可能なことが確認できた。他方、気液二相流について、別途、気液二相流を発生させる装置を試作し、気泡径の違いが管内気液二相流において流動構造に及ぼす影響を調べた。特に急拡大部を通過する気泡流について着目し、局所ボイド率、気泡径、気泡径の度数分布を計測し、気泡の合体、分裂の発生状況について調べた。次に、その気泡発生装置による気泡流を回流式水槽試験装置の流路に混入して片持ち弾性支持した有限スパン長さ円柱の流力振動特性を調べ、気泡混入による流力振動に及ぼす影響を明らかにした。現時点の実験結果によれば、現行の「配管内円柱状構造物の流力振動評価指針」はいずれの場合にも妥当であることなど、貴重な試験結果を得た。; This study are for providing important data to support and develop "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. Flow-induced in-line oscillation of a cantilevered circular cylinder model like a thermocouple that is actually used in industrial plants has been experimentally studied by free-oscillation tests in a water tunnel.Free- oscillation test for a cantilevered model like a thermocouple in a water (a single- phase flow): The response tip amplitudes of a circular cylinder were measured at varying reduced velocity from 1.0 to 4.0. A cantilevered cylinder was supported by plate spring mounted on the water tunnel wall. The aspect ratio of a cylinder was varied from 5 to 21 to investigate the effect of aspect ratio on the response amplitude. It is found that the cylinders with aspect ratio of 5 and 10 show one excitation region, but the cylinders with aspect ratio of 14 an d 21 showed two excitation regions. The aspect ratio, therefore, strongly affects the amplitude of the second excitation region. The influence of end-effect also was investigated using cylinders with an end plate attached on the free end. Because the cylinders with an end plate show two excitation regions even if the cylinder has an aspect ratio of 5, the flow around the free end of cantilevered cylinder makes the end-effect. The mechanism of vibration was investigated using a cylinder with a splitter plate in wake to prevent the alternate vortices. The amplitude is bigger than normal cylinder especially at the reduced velocity from 2.3 to 3.0 where the cylinder attached an end plate shows the second excitation region; that is to say, the alternate vortices suppress the amplitude in this range. The maximum amplitude of each excitation region decreases in proportion to the reduced dumping parameter and the amplitude of the first excitation is more sensitive to that parameter. The amplitudes are suppressed in each excitation region when the reduced dumping parameter is greater than 2.5 with each aspect ratio of 10 and 21.Free- oscillation test for a cantilevered model in two-phase flow: As the fundamental study on flow-induced in-line oscillation of a cantilevered circular cylinder model in two-phase flow, the variations of void fraction, bubble diameter and bubble velocity are measured using an electrical resistivity probe when two-phase flow goes through the region of sudden area expansion in the vertical pipe. In this study two different radial void distributions in the pipe are considered. One is called as sliding flow regime, which occurs when the bubble diameters are less than 5mm. The other is termed as coring flow regime, which takes place when the bubble diameters are greater than 5mm. And the response amplitudes of a circular cylinder have been measured by the free-oscillation tests in the two-phase flow in a water tunnel. Comparing the response amplitudes with the results in a water, we found that the flow-induced vibration are suppressed by the two phase flow.; 研究課題/領域番号:11555054, 研究期間(年度):1999-2001; 出典：「配管内気液二相流中における円柱状構造物の流力振動予測と設計評価ガイドラインの開発」研究成果報告書 課題番号11555054 (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: 10.24517/00049364
• Source: https://kanazawa-u.repo.nii.ac.jp/?action=repository_action_common_download&item_id=43015&item_no=1&attribute_id=26&file_no=1
• Access Restrictions: 限定公開
• Rights (production): CC BY-NC-ND
• Related Material: https://kaken.nii.ac.jp/search/?qm=80013689; https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11555054/; https://kaken.nii.ac.jp/report/KAKENHI-PROJECT-11555054/115550542001kenkyu_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