二維方柱橫向與扭轉向振動耦合之氣動力研究

Aerodynamic forces of a square prism in transverse and torsional coupled motion

呂宜靜(Yi-Ching Lu)

指導教授 ： 盧博堅

淡江大學/工學院/水資源及環境工程學系碩士班/碩士(2005年)

https://doi.org/10.6846/TKU.2005.00363

摘要

本研究將探討一二維方柱體在受強制振動影響下，改變其橫風向與扭轉向振動間的頻率比及二維方柱之偏心量，進而瞭解橫風向與扭轉向振動間發生耦合時，結構物所產生之氣動力現象。
結果顯示，當Fr大於1.0時，在勁度中心往上游偏離，偏心量為10％時可得最小的擾動昇力係數峰值及渦散頻率的尾跡風速；而在勁度中心往上游偏離，偏心量為20％可得最大的擾動昇力係數峰值及渦散頻率的尾跡風速。當Fr等於1.0時，在勁度中心往上游偏離，偏心量為10％時可得最大的擾動昇力係數峰值及渦散頻率的尾跡風速；而在勁度中心往上游偏離，偏心量為20％可得最小的擾動昇力係數峰值及渦散頻率的尾跡風速。與Fr大於1.0正好相反。當Fr小於1.0時，在勁度中心無偏離時，可得最大的擾動昇力係數峰值及渦散頻率的尾跡風速；而最小值則不一定發生在哪一個偏心上。

關鍵字

二維方柱 ； 強制振動 ； 頻率比 ； 偏心量

並列摘要

Wind tunnel measurements were performed to study the aerodynamic
phenomenon of a two dimensional prism when the mass center separates from the center in transverse and torsional coupled vibration modes.

When the torsion/transverse frequency ratio (Fr) is greater than 1.0, as long as the eccentricity is introduced in the upstream direction at 10%, the spectral peaks of the lift fluctuation coefficient and the vortex shedding reach a minimum value compared with other eccentricities. However, as the eccentricity increases to 20%, the spectral peaks reach a maximum value.

Whereas when Fr=1, eccentricity 10% and 20% in the upstream direction, the spectral peaks of lift fluctuation coefficient and vortex shedding show the opposite trend. A maximum value is obtained when Fr is smaller than 1.0 and without eccentricity. However, there is no obvious trend for the minimum value.

並列關鍵字

A square prism ； forced vibration ； ratio of frequency ； eccentricity

參考文獻

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