臺灣博碩士論文加值系統

本論文針對雙平面平行噴流，在水槽中使用實驗方法觀察噴流的流場特徵。平面噴流是出口長寬比為20:1的狹長槽，噴流出口速度條件為拋物線速度分佈。實驗參數為噴流雷諾數、噴流速度比及噴流中心間距。在不同的實驗參數條件下，使用雷射光頁輔助質點軌跡流場可視化，擷取雙平面平行噴流的噴流瞬時流場影像。藉由質點影像速度儀的應用，量化雙平面平行噴流之流場特徵結構的全域速度場，計算雙平面平行噴流的速度向量場、流線圖、渦度分佈及紊流強度。針對不同的實驗參數，探討雙噴流之匯合與結合的特性，對紊流特性與渦度的影響。實驗結果呈現低速噴流往高速噴流偏折並匯合，在靠近匯合點附近的產生較大的紊流動能。紊流強度隨著速度比增加而增強，隨著雷諾數增加，渦度值及渦度集中的範圍變大。兩噴流之間交互作用隨著噴流中心間距增加而減弱，因此，在小噴流中心間距時的紊流性質比大噴流中心間距時的紊流性質大。當噴流出口端部穿裝側檔板時，兩噴流之間的交互作用增強，所以紊流動能增加，匯合點往噴流上游移動，造成迴流區變小。

The flow characteristic of two parallel planar jets was experimentally investigated in a water tank. The aspect ratio of the planar jet was 20:1. The jet-exit flow condition was a parabolic velocity profile. The experimental parameters include jet Reynolds number, jet velocity ratio, and jet spacing. Under various experimental parameters, the flow behavior of the two parallel planar jets was captured by laser-assisted particle-tracking flow visualization. The velocity field of the characteristic flow behavior was quantified by employing the particle image velocimetry technique. The velocity fields, streamline patterns, velocity distributions, turbulence intensity distributions, vorticity contours, and turbulence kinetic energy contours of two parallel planar jets at various experimental parameters were simultaneously determined and presented. The effect of merging and combined characteristics on turbulence intensities, mean vorticities, and turbulence kinetic energies were examined. Experimental results revealed that the jet with low velocity evolved from jet exit deflects toward the large jet-velocity side. The distance of merging point from the jet exit increases with increasing velocity ratio. The large turbulence kinetic energy appears at around merging point. The turbulence intensity increases with increasing velocity ratio. The vorticity magnitude and vorticity concentrated area enlarge as the Reynolds number increases. The interaction of two jets is weakened as the jet spacing increases; therefore, the turbulence properties of two parallel planar jets at small jet spacing are larger than those at large jet pacing. As the side plates are installed at the end of the planar jets, the interaction of the two jets is enhanced and therefore the turbulence kinetic energy increases. The merge point moves upstream and the recirculation region decreases.

摘要................... i
Abstract............... ii
誌謝................... iv
目錄................... v
表目錄................. ix
圖目錄.................. x
符號索引................ xxvii
第一章 緒論............. 1
1.1 研究動機............ 1
1.2 文獻回顧............ 1
1.3 研究目的............ 3
第二章 實驗設備、儀器與方法....... 5
2.1 實驗設備............ 5
2.2 實驗儀器............ 5
2.2.1 流量計............ 5
2.2.2 流場可視化.........6
2.2.3 質點影像速度儀..... 7
2.3 實驗方法............ 8
2.3.1 合併點與結合點的量測方式.... 9
第三章 無側檔板之雙平行平面噴流... 10
3.1 流場可視化................. 10
3.1.1 s/d = 5之流場可視化....... 10
3.1.2 s/d = 10之流場可視化...... 11
3.2 速度向量流線圖.............. 12
3.2.1 s/d = 5的平均速度向量流線圖........ 12
3.2.2 s/d = 10的平均速度向量流線圖....... 13
3.3 橫向速度分佈及紊流強度............... 14
3.3.1 s/d = 5的橫向速度分佈及紊流強度..... 15
3.3.2 s/d = 10的橫向速度分佈及紊流強度.... 17
3.4 等渦度分佈.......................... 18
3.4.1 s/d = 5之等渦度分佈............... 19
3.4.2 s/d = 10之等渦度分佈.............. 20
3.5 紊流動能............................ 21
3.5.1 s/d = 5之紊流動能................. 21
3.5.2 s/d = 10之紊流動能................ 22
3.6 合併點與結合點....................... 22
3.7 噴流軌跡............................ 22
3.7.1 s/d = 5之出口中心軌跡及噴流速度位置......... 23
3.7.2 s/d = 10之出口中心軌跡及噴流速度位置........ 23
第四章 有側檔板之雙平行平面噴流........... 24
4.1 流場可視化.......................... 24
4.1.1 s/d = 5之流場可視化............... 24
4.1.2 s/d = 10之流場可視化.............. 25
4.2 速度向量流線圖...................... 26
4.2.1 s/d = 5的平均速度向量流線圖.........26
4.2.2 s/d = 10的平均速度向量流線圖....... 27
4.3 橫向速度分佈及紊流強度............... 28
4.3.1 s/d = 5的橫向速度分佈及紊流強度..... 28
4.3.2 s/d = 10的橫向速度分佈及紊流強度.... 30
4.4 等渦度分佈.......................... 31
4.4.1 s/d = 5之等渦度分佈............... 32
4.4.2 s/d = 10之等渦度分佈.............. 33
4.5 紊流動能............................ 34
4.5.1 s/d = 5之紊流動能................. 34
4.5.2 s/d = 10之紊流動能................ 35
4.6 合併點與結合點....................... 35
4.7 噴流軌跡............................ 35
4.7.1 s/d = 5之出口中心軌跡及噴流速度位置......... 35
4.7.2 s/d = 10之出口中心軌跡及噴流速度位置........ 36
第五章 結論與建議........................ 37
5.1 結論............................... 37
5.2 建議............................... 37
參考文獻................................ 194
Extended Abstract...................... 196
Abstract............................... 196
1. Introduction........................ 197
2. Experimental methods................ 197
3. Results and discussion.............. 198
References............................. 201

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