| 研究生: |
韓亞軒 Han, Ya-Shuan |
|---|---|
| 論文名稱: |
多孔噴嘴在漩渦效應下之霧化現象 Atomization Performance of Mutiple-Orifice Nozzle Under Swirler Effect |
| 指導教授: |
王覺寬
Wang, Muh-Rong |
| 學位類別: |
碩士 Master |
| 系所名稱: |
工學院 - 航空太空工程學系 Department of Aeronautics & Astronautics |
| 論文出版年: | 2004 |
| 畢業學年度: | 92 |
| 語文別: | 中文 |
| 論文頁數: | 129 |
| 中文關鍵詞: | 漩渦器 、多孔 、霧化 、氣助式噴嘴 |
| 外文關鍵詞: | swirl, air-assist atomizer, atomization, multiple-orifice, spray |
| 相關次數: | 點閱:88 下載:2 |
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本研究探討氣助式多孔噴嘴配備不同漩渦器對霧化特性之影響。漩渦器主要功能是令液體產生側向動量,形成液體薄膜化之霧化機制,以提昇噴嘴之霧化品質。本實驗所採用之漩渦器分別具有10mm、20mm及30mm等三種長度,噴嘴孔口直徑為0.8mm之奇點式孔口結構,孔數分為八孔、六孔及四孔等三種不同排列方式,噴嘴材質採用不銹鋼及硬化塑膠等不同材質。噴霧粒徑分佈利用INSITEC RT-sizer粒徑分析儀做即時量測。
實驗結果顯示,配備10mm漩渦器之噴嘴,其液體流經漩渦器流道較短,損失的動能較少,有較佳的平均粒徑(SMD)。例如在水壓5.0bar,氣壓6.0bar下,配備10mm、20mm、30mm漩渦器噴嘴之平均粒徑分別為6.30μm、6.48μm及7.06μm。在漩渦器的裝配方式方面,實驗結果發現,固定式漩渦器因不需以部分流體之能量去轉動漩渦器,故固定式漩渦器有較佳之霧化特性,其平均粒徑與標準差均較小。在多孔噴頭孔口幾何排列方式對霧化特性之影響方面,實驗結果顯示,在相同的孔徑,相同的孔數,相同的操作壓力下,改變孔口排列方式就可改變噴霧流場中之霧化機制,進而改善噴霧器的粒徑大小與分佈範圍。研究結果發現雙層交叉八孔噴頭(cn8)排列方式可得最佳之霧化效果,在不同的操作壓力下,此種(cn8)噴嘴均可產生較佳的霧化品質,例如在氣壓6.0bar,水壓5.0bar,cn8噴嘴的平均粒徑為5.82μm,標準差為8.95μm,比其他排列方式顯著提昇。噴嘴材質方面,比較不銹鋼和硬化塑膠兩種材質對霧化特性之影響,發現不銹鋼為親水性材質,當水通過流道時會產生擾動和薄膜化的現象,增加霧化機制使霧化品質提昇。綜合以上實驗的結果顯示,雙層交叉式孔口排列方式配備較短漩渦器之親水性噴霧器具有較佳的霧化特性。
This research program investigates the effects of multiple orifices on atomization performance of an air-assist atomizer with swirler effect. The function of the swirler is to enhance the lateral momentum of the liquid phase to, produce a prefilming atomization mechanism. Experiments compare the atomization performance of the swirlers with length of 10mm, 20mm and 30mm, respectively. The orifices of the nozzle are designed in a singularity configuration with 0.8mm in diameter of the nozzle. There are 4, 6 and 8 orifices and designed in different patterens. The atomizer’s materials are stainless steel and plastic. The particle size of the spray is measured by INSITEC RT-sizer .
Results show that the atomizer with 10mm swirler has better performance because it loses less kinetic energy due to the shorter channel in the swirler. As a typical example, the mean particle sizes produced by the atomizers with 10mm, 20mm and 30mm swirler are 6.30μm, 6.48μm and 7.06μm, respectively. Results also show that the stationary-type swirler has better atomization performance compared to the rotating one. The kinetic energy of atomization gas is partially transfer to the rotating swirler, hence the atomization energy transferred to the liquid phase is less. It turns out that the mean particle size and the standard deviation(σ)associated with the stationary swirler are smaller. The geometric arrangement of multiple orifices also influence the atomization performance. Results show that the nozzle with eight orifices arranged in double-crossing pattern (ie, cn8-nozzle) results in the best atomization performance. For example, the cn8-nozzle produces spray with mean particle size and standard deviation of 5.82μm and 8.95μm, respectively, under test condition of (Pa , Pw)=(6.0,5.0) bar. Tests on the nozzle material show that the nozzle with stainless steel has better atomization performance. It seems that stainless steel is hydrophilic and is useful in the enhancement of the prefilming mechanism of the liquid phase during the atomization processes. In summary, the nozzle made of hydrophilic material with doubt-crossing orifices and short swirler has the optimum atomization performance.
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