臺灣博碩士論文加值系統

本研究係針對機車引擎進氣歧管內的流場結構對噴油霧化情形進行研究評估。為了改變進氣歧管內的流場結構，於節氣門(蝴蝶閥)下游處裝置不同幾何形狀設計之葉片環，利用FLOWORK模擬其流場在管內以及進入汽缸時的速度分佈及流線情形，其後再以雷射粒徑儀量測無裝置葉片環以及加裝各個葉片環後的粒徑大小分布，並以電子天平量測相同狀況下所收集之油滴浸潤量。實驗中主要工作參數為不同的節氣門開度、葉片環模型以及汽缸進氣閥門桿的作動與否。而實驗結果顯示不論是否改變進氣歧管內的流場結構，節氣門的開度越大，所測得的粒徑越小。而進氣閥門的作動則因為會導致不可預期的大顆液滴，使得平均粒徑值變大。裝置葉片環後的歧管流道雖然所量測到的粒徑皆大於無葉片裝置的歧管流道，但在油滴浸潤量的收集部分卻有著比較良好的結果，歸咎於其流場結構改變後，其流場內具有明顯的旋轉特徵，因而增加了油滴粒子碰撞結合的機會，也降低了附著於歧管管壁上之油膜累積形成液態油滴流入汽缸的機會。綜合模擬及實驗數據的結果可發現，改變進氣歧管內的流場結構確實可對噴嘴噴油之霧化情形以及汽缸與管壁壁面所附著之燃油液滴狀態造成一定程度之影響。

This study carries out the research assessment of the effects on the characteristics of oil spray by the flow structure inside the engine inlet manifold of a motorcycle. Stator ring with different blade design were installed upstream of the manifold in order to change the flow structure. Commercial software FloWork was used to simulate the flow field before and after airflow entering the cylinder. The characteristics of the oil spray were then evaluated using laser particle sizer, together with balance for oil wetting measurement. Major experiment parameters in this research include different throttle openings, stator ring designs and the actions of the inlet valve of the cylinder. The experimental result reveals that no matter how the flow structure changes, the more the throttle opening, the smaller the SMD value. The motion (open-close) of the inlet valve will increase the oil particle size due to the existence of unexpected huge oil droplets. Although the installation of stator rings in general increase the SMD value, however, the oil wetting at the wall was dropped clearly. This outcome may be attributed to the change of the flow structure, which imposes rotating motion to the flow field and provides better chance for the oil droplets to collide and combine, and brings the oil back to the flow field from the oil film on the wall and prevents liquid oil flows into the cylinder too. Based on the comprehensive simulation and experimental result, it is clear that the change of flow structure inside the inlet manifold can indeed influence the characteristics of the oil spray and the oil wetting at the wall.

中文摘要 ………………………………………………………………... I

英文摘要 ………………………………………………………………... II
誌謝 ………………………………………………………………... III
目錄 ………………………………………………………………... IV
圖目錄 ………………………………………………………………... VI
表目錄 ………………………………………………………………... X
符號說明 ………………………………………………………………... XI

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