本研究藉由實驗方法，研究小圓柱尾流衝擊平板時，對平板迎風面之流場與氣動力性能的影響。藉由雷射光頁輔助煙霧可視化技術，觀察小圓柱尾流流場特徵及平板表面受小圓柱尾流衝擊時之流場特徵。以熱線風速儀偵測小圓柱尾流區域的渦漩逸放特性與速度分佈以及平板受小圓柱尾流衝擊時接近表面附近的速度分佈。使用質點影像速度儀(PIV)，量取平板受小圓柱尾流衝擊表面上游之速度場，得到量化的流場結構。使用壓力掃描技術量測平板表面的壓力分佈，探討小圓柱對平板表面壓力分布的影響。針對不同雷諾數，在小圓柱尺寸與平板寬度的域面上，紀錄平板上游的流場特徵行為。分析流場可視化、熱線風速儀偵測、迎風面壓力量測及量化速度場的結果顯示：流場行為可劃分為穩態域(stable regime)與非穩態域(unstable regime)兩種特徵模態。穩態域中的流場特徵為小圓柱的尾流會在接近平板表面的上游區引致一些特徵流場結構，可分成三個子模態：在低雷諾數區形成兩個轉向相反且近似對稱的迴流；在中雷諾數區形成一蕈狀渦漩結構；在高雷諾數區，蕈狀渦漩結構上游另呈現一至三個小渦漩結構。在非穩態域中的流場特徵，平板表面的蕈狀渦漩結構不會穩定存在在平板上方，而是呈現不規則的逸放行為。在穩態域中，由於接近表面上游區的蕈狀渦漩結構的生成，避免橫風直接衝擊平板表面，因此降低平板上方的壓力係數值約5.2%。

The characteristics of flow characteristics and aerodynamic performance of a flat plate impinged by the wake of a small-diameter circular cylinder were experimentally studied in a wind tunnel. The aims were focused on improving the flow behavior and aerodynamic performance of the flat plate. The effects of varying the dimensions of a small-diameter circular cylinder on the flow characteristics upstream the flat plate were observed by laser-assisted smoke flow visualization technique. A one-component hot-wire anemometer was used to detect the instantaneous velocities in the wake of the small-diameter circular cylinder. The distributions of surface pressure coefficient of the flat plate were measured by using a home-made linear pressure scanner. The pressure coefficients were subsequently calculated by dividing the measured surface pressure by the dynamic pressure of freestream. The velocity fields upstream the flat plate were quantified by employing the Particle image velocimetry (PIV). The streamline patterns and turbulence properties of various characteristic flow models were presented. The characteristic flow regimes were identified in the domain of the nondimensional diameter of small circular cylinder and the nondimensional width of flat plate. The flow visualization results showed two characteristic flow regimes (stable and unstable) identified in the domain of small circular cylinder diameter and the flat plate width. By cross referencing and analyzing the results of flow visualization, hot-wire anemometer detection, surface pressure measurement, and PIV measurement, the effects of the small-diameter circular cylinder on the characteristics of flow behavior and aerodynamic performance of the flat plate was unveiled and discussed.

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