微型多孔噴流在共振下之霧化機制及其特性研究

Atomization Mechanism and Performance of Multiple Micro-Jets with Resonance Effect

王覺寬(Muh-Rong Wang) ； 李冠憲(Kwang-Sen Lee)

《航空太空及民航學刊.系列B》 43卷2期 (2011/10) Pp. 65-72

https://doi.org/10.6124/JAAA.201110_43(2).01

摘要

本研究探討不同孔徑之多孔微型噴嘴之霧化機制及其霧化特性，微型噴頭大小孔徑分別為200μm、100μm，共振腔直徑為3000μm，共振腔高度為400μm，孔距在400μm到2000μm之間，工作流體為純水。研究項目包括多孔噴頭不同孔徑微液束之暫態演變過程，並探討大小孔間配置流道之連通效應對其霧化特性之影響。本研究以Insitec RT-Sizer粒徑分析儀量測噴霧平均粒徑及粒度分佈。研究結果顯示，不同孔徑大小之液束在形成穩定液束過程中，存在噴射延遲之現象。而且此延遲現象隨孔距增加而遞增，顯示改變相鄰孔口間距，可以改變液柱之霧化現象。噴霧特性量測結果顯示，多孔微噴嘴所呈現之噴霧結構皆為實心噴霧，噴霧濃度與SMD皆由噴霧中心往外圍遞減。若雙孔孔距變小，因為液體交互作用下之不穩定能量遞增，故在壓力125bar下，具有共振效應下噴霧平均粒徑SMD可由9.04μm遞減至5.49μm，並且噴霧產量可達15.21kg/hr。若在孔口間加上連通流道設計，可增進不穩定破裂模態之強度，形成更微小之液滴，故在噴射壓力125bar下噴霧粒徑進一步降為5.38μm，且噴霧產量達14.40kg/hr。故知孔距縮小會增加不同孔徑液體間之交互作用，促使液束具有更不穩定之破裂過程。若在不同孔徑之雙孔間配置一流道設計，會產生液體連通之交互效應，激發液束之不穩定能量，故會產生較佳之霧化效果。結果顯示此種微噴嘴霧化性能與噴霧產量皆優於傳統柴油噴嘴及工業用之壓力式噴嘴。

關鍵字

霧化 ； 多孔噴流 ； 壓力式 ； 噴流交互作用 ； 共振腔

並列摘要

Enhancement of atomization performance of pressure atomizer with multi-apertured nozzles was investigated in this paper. The orifice plates of the nozzle are designed with multiple orifices having diameters 100 μm and 200 μm, with pitches ranging from 400 μm to 2000 μm. The diameter and height of the resonator are 3000 μm and 400 μm, respectively. The working medium used for atomization is water. The evolution of the transient processes of the multi-jet emergence and the performance of the orifices with cross-link channel will be presented. The particle size was measured by the Insitec RT-Sizer. It was found that there is a time lag between the formation of liquid jet with different orifice size. The time lag increased as the pitch between orifices was increased indicating the interaction between the nearby orifices. It was also found that the liquid jet became a solid cone spray jet and SMD of the spray decreased from 9.04μm to 5.49μm as the pitch was reduced to 400μm under the injection pressure of 125bar using double orifices plate with a resonator. The production rate of the spray was 15.21kg/hr in this case. Furthermore, the cross-link channel between the orifices enhanced the interaction between two liquid jets. It, in turns, enhances the performance of atomization under lower pressure. The SMD of the spray was lowered to 5.38μm and the production rate was increased to 14.40kg/hr under injection pressure of 125bar. It turns out that the reduction of pitch between orifices may result in the interaction of the liquid jets and enhance the instability modes during the breakup processes. Moreover, the channel between the orifices would further increase the instability energy of the liquid jets. As a result, the new atomizer performs better as comparing to the traditional diesel-type atomizers and the industrial pressure atomizers.

並列關鍵字

Atomization ； Multiple jets ； Pressure atomizer ； Jet interactions ； Resonator