本研究探討平板在橫風中受雙小圓柱尾流衝擊，在不同的雷諾數及不同的小圓柱軸心線距時的流動現象以及平板的受力行為。在風洞中設置平板以及雙小圓柱，使用雷射光頁輔助煙霧可視化法拍攝流場的連續演化；利用熱線風速儀量測流場中渦流的週期特性；使用質點影像速度儀(Particle Image Velocimetry)量測流場速度分佈，繪製成速度向量流線圖以及渦度分佈圖，並計算紊流強度。於平板之迎風面及背風面設置多個細小壓力孔，量測平板迎風面及背風面的壓力，將量測到的壓力數值轉換為壓力係數，再將壓力係數積分獲得平板的阻力係數。研究結果顯示，各模態的流場、渦度、空氣動力特徵隨著兩圓柱軸心線距及雷諾數改變，而在不同區域內呈現不同現象。平板上游會呈現單顆蕈狀渦漩或雙顆蕈狀渦漩結構，各蕈狀渦漩結構之特徵直徑大小不同，兩股尾流在平板上游前的特徵也會受到上述兩個因素影響，造成平板上游蕈狀渦漩結構變化，進而影響平板氣動力特性。在不同的雷諾數與兩小圓柱軸心線距區域，平板上游的流場特徵可劃分為兩大主要的特徵模態，分別為；Single mushroom vortex及Dual mushroom vortices模態。主模態又可區分為八個子模態；Separated wakes steady vortices、Separated wakes unsteady vortices、Separated wakes periodic merging vortices、Separated wakes nonperiodic vortices、Separated wakes steady vortex、Merged wake steady vortex、Separated wakes periodic vortex、Merged wake nonperiodic vortex模態。當兩圓柱尾流撞擊平板時與未放小圓柱時的阻力係數相比，大約可使阻力係數降至10%左右。

The study investigated the flow phenomena and aerodynamic behaviors of a flat plate subjected to the impingement of dual-cylinder wakes created downstream of two small circular cylinders. The primary physical and geometric parameters influencing the flow properties were Reynolds number and non-dimensional distance between cylinder axises, respectively. The laser light sheet-assisted smoke visualization technique was used to capture the time-evolution images of the flow field. The frequencies of the periodic vortex evolution processes were measured by a one-component hot-wire anemometer. The velocity fields were measured by particle image velocimetry (PIV). Velocity vectors, streamlines, vorticity, and turbulence intensities were analyzed based on the measured velocity data. The surface pressures on both sides of the flat plate were fetched from the pressure taps drilled on both sides of the flat plate. The measured pressures were converted into pressure coefficients. The drag coefficients were subsequently obtained by integrating the pressure coefficients over both surface areas of the flat plate. The results showed that the flow patterns, vorticity distributions, and aerodynamic performances were significantly subject to the influences of the Reynolds number and the non-dimensional distance between cylinder axises. Multiple complex characteristic flow modes were observed in the domain of the Reynolds number and the non-dimensional distance between cylinder axises. The primary characteristic flow modes were single and dual mushroom vorteices. Several secondary characteristic flow modes were identified within regime of the primary characteristic flow modes. When compared with the natural flat plate, the dual-cylinder wakes impingement on the flat plate induced decrease in drag coefficient by approximately 10% in some characteristic flow modes.

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