圓柱體形建築物表面風壓之實驗研究; pressure distribution on the surface of three-dimensional circular cylinder in a boundary layer flow

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题名:	圓柱體形建築物表面風壓之實驗研究;pressure distribution on the surface of three-dimensional circular cylinder in a boundary layer flow
作者:	李肇軒;Tsao-Hsuan Li
贡献者:	土木工程研究所
关键词:	圓柱體;擾動壓力;粗糙度;pressure fluctuation;surface roughness;circular cylinder
日期:	2002-05-28
上传时间:	2009-09-18 17:09:06 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本研究以風洞實驗的方式探討邊界層流中三維圓柱體形建築物表面的壓力分佈情形。實驗條件包括光滑圓柱體以及兩種不同粗糙度的圓柱體，實驗中使用電子式壓力掃描器，可同時量測多個位置的瞬時壓力。由實驗結果可計算得建築物表面的平均、擾動、最大壓力分佈與流場分離點位置。研究結果顯示：圓柱體的最大擾動壓力發生在最大負壓發生處；當圓柱體粗糙程度增加時，圓柱體的最大負壓和擾動壓力隨之減少。且最大負壓發生處和圓柱體分離點的平均位置皆會隨著粗糙度增加而往迎風方向移動，分離點移動的範圍則會隨著粗糙度增加而變小。風壓頻譜顯示渦流逸散頻率為12 Hz，史徹荷數為0.21，與二維圓柱體的史徹荷數相近。本研究之結果可幫助吾人瞭解對邊界層流中三維圓柱體表面粗糙度對流況與壓力分佈的影響，可供相關工程設計之參考。 This study experimentally investigates the pressure distribution on the surface of three-dimensional circular cylinder in a boundary layer flow. The experiments were carried out in an atmospheric boundary layer wind tunnel. The flow conditions include three different kinds of surface roughness. Instantaneous fluctuating wind pressures were measured by an electronic pressure scanner. Based on the pressure measurement, the distributions of mean, rms Cprms, peak pressure Cpp and separation point can be calculated. It was found that the maximum Cprms occurs at the location of minimum negative pressure. Also, the separation point and the location of minimum negative pressure will move toward upstream direction as surface roughness increase. Even under the same surface roughness, the separation point will move within certain range in turbulent flow. The moving range of separation point will decrease as surface roughness increase. The experimental results also revealed that the probability of pressure fluctuations for positive pressure are close to the Gaussian distribution function. On the other hand, negative pressure side was skewed and did not necessary follow Gaussian distribution.
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