本研究藉由實驗方法研究兩道相鄰、平行且等速的二維噴流在不同間隔時的流動型態與流場特性。空氣由高壓桶供應，將空氣導入一個大體積的空腔中，經整流後從空腔頂部一片具有平行的兩道細槽之平板噴出，兩道細槽之噴流出口具有ASME low 系列噴嘴的形狀。經由置換不同的空腔頂部的平板，可以改變兩道相鄰且平行噴出之二維噴流出口之間的距離。二維噴流出口之寬度d = 4 mm，長度w = 145 mm；兩道噴流出口中心之間的距離s與噴流出口寬度d的比值為 s/d = 3, 5, 8, 10, 15。藉由電子式質量流量計量測噴流供應質量，轉化為一大氣壓標準溫度下的體積流率，除以噴流出口面積獲得噴流出口速度，再換算為噴流出口雷諾數Rej，Rej= 200 ~1600。利用雷射光頁輔助煙霧流場可視化技術搭配高速攝影機，擷取瞬時流場影像；應用高速質點影像測速儀(PIV)量測兩道相鄰二維噴流橫向速度場。觀察煙霧流場可視化之影片與照片，在噴流間隔與雷諾數變化時，可分辨出兩種流場特徵模態：(1)噴流往下游運動時互相吸引而內傾，經一段往下游距離後結合在一起，結合之後噴流因剪力效應而產生之凝聚性渦漩結構才破碎成紊流，通常發生在較小的s/d，稱為CBVB (combination before vortex breakup)、(2)噴流往下游運動，經一段往下游距離後靠攏結合在一起，結合之前噴流因剪力效應而產生之凝聚性渦漩結構已開始破碎成紊流，通常發生在較大的s/d，稱為CAVB (combination after vortex breakup)。PIV量測結果顯示，兩噴流之間靠近噴口附近會形成一個迴流區，迴流區中包含兩個轉向相反的渦流。迴流區的頂點在中心線上，稱為匯流點(merge point, MP)，是個四向鞍點；在匯流點下游，兩噴流結合之後，速度在中心線變成橫向分佈最大值時的軸向位置稱為結合點(combine point, CP)。速度場的軸向與橫向分佈、CBVB與CAVB在s/d-Rej的區域分佈以及匯流點與結合點的軸向座標在本文中皆有討論。

The flow characteristics of two parallel plane jets were experimentally studied. The widths and lengths of the jet exits were 4 mm and 145 mm, respectively. The ratios of the spacing between the two neighboring jets to the width of the jet exits were 3, 5, 8, 10, and 15. According to the smoke-flow visualization results, two characteristic flow modes, combination before vortex breakup (CBVB) and combination after vortex breakup (CAVB), were identified in the domain of non-dimensional jet spacing and jet Reynolds number. Coherent structures evolved in the shear layers of the jets issued from the jet exits and expanded laterally as the jets travelled downstream. The CBVB mode appeared at small non-dimensional jet spacing. The jet columns inclined slightly toward the centerline due to the slightly low pressure existing between the neighboring jets in the near field. The shear-layer coherent structures merged together, broke up into small eddies, then combined into a single jet to evolve to downstream area. The CAVB mode appeared at large non-dimensional jet spacing. The neighboring jets combined into a single jet to evolve to downstream area first, then the shear-layer coherent structures merged together and broke up into small eddies. The PIV measured velocity fields showed a recirculation region consisted of two counter-rotating vortices existing between the jets near the jet exits. The apex of the recirculation region was a four-way saddle which was a merge point (MP) of the two parallel plane jets. Around the centerline upstream the MP, the flow velocities were reversed. Around the centerline downstream the MP the flow velocity pointed downstream. However, the lateral velocity profiles presented a deficit around the centerline. As the lateral velocity profiles evolved downstream, the velocity deficits around the centerline became smaller and smaller, and finally attained a local maximum at an axial distance downstream the MP. The location where the centerline velocity became the maximum of the lateral velocity profile was termed the combined point (CP). The velocity distribution in axial and lateral directions, characteristic flow regimes, axial lengths of the MP and CP were presented, analyzed, and discussed.

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