本研究以風洞實驗的方式探討在穩態風場及陣風風場中三維圓柱體及矩柱體建築物模型表面壓力之分佈情形。實驗條件包括無陣風以及三種不同頻率的週期性陣風風場，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、擾動壓力分佈與機率密度函數，風壓頻譜分析方法採用傅立葉頻譜分析及希爾伯特-黃分析兩種方法。研究結果顯示：陣風風場之平均壓力係數分佈趨勢與穩態風場、邊界層流十分接近，數值則介在兩者之間，可將陣風視為一種過渡流；圓柱體的最大擾動壓力發生在最大負壓發生處，陣風來流造成圓柱體在迎風面及分離區的擾動壓力增大；由傅立葉頻譜分析及希爾伯特-黃分析之風壓頻譜結果顯示圓柱體渦流逸散頻率為13 Hz，史徹荷數為0.22；窄迎風面矩柱體渦流逸散頻率為10 Hz，史徹荷數為0.082，較邊界層流與陣風風場中的史徹荷數為小。當陣風頻率增大時，史徹荷數增大，顯示渦流逸散頻率增加。本研究之結果可幫助吾人瞭解對穩態風場與陣風風場中三維圓柱體及矩柱體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 building model in an uniform flow and periodically varying flows. The experiments were carried out in an atmospheric boundary layer wind tunnel. This wind tunnel is equipped with a gust generator that can generate periodically varying flows of adjustable frequency. Flow condition includes one rectangular cylinder and one circular cylinder of smooth surface. Instantaneous fluctuating wind pressures were measured by an electronic pressure scanner. Based on the pressure measurement, the distributions of mean, rms pressure coefficients were calculated. Furthermore, Hilbert-Huang Transform (HHT) was used for the time-frequency domain analysis. The experimental results also revealed that the rms pressure coefficient increase under gusty wind. Also, 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.
