近年來，汽車整體造型朝流線型發展，汽車頭燈設計隨之多變化，導致頭燈內部之配置也趨複雜化，頭燈內部容易有氣流不易流通至狹窄角落之情況，因此容易於角落區域產生霧氣之情形。
本研究之目的主要將實驗所量得之燈泡表面溫度當以模擬時所需之熱源條件，再藉由CFD軟體對頭燈內部進行流場之數值分析，探討在僅改變通氣孔大小、數目、位置之條件下，對產生霧氣區域流場之影響，來尋求最佳化之排氣孔設計，進而克服頭燈霧氣之情況。
由CFD模擬結果顯示，在考慮引擎熱以及僅開啟通氣孔Vent3之條件下，加大通氣孔之管徑，於Corner處速度分佈維持不變，而Side處之最低流速下降50%；此外，在考慮頭燈內部濕度情況下，相較於原設計之通氣孔情況，可將Side處之最大相對濕度降低約34.9%，Corner處也可降低1%。另外，在考慮不同通氣孔位置、數量以及引擎熱影響，探討於最低速度時，同時開啟Vent3及Vent6，其Corner及Side最低速度均較僅開啟Vent3佳，分別約可上升19.4%及50%；但當考慮其濕度情況時，於Corner及Side兩區域內之最高相對濕度反而上升，故可將此歸類為一非理想情況。因此，於通氣孔之情況選擇上，可考慮將原設計之通氣孔管徑增加25%，以降低霧氣產生。

In recent years, streamlining becomes essential in vehicle designs, and the design of headlamps is no exception which leads to complex internal structures. The common moisture problems can occur while the flow inside the headlamps moves to narrow corners and spaces. This study uses measured temperatures on the headlamp surfaces as the heat sources while simulating, by a CFD software to analyze the flow fields inside lamps. The effects of moisture are primarily discussed by changing the conditions, such as different sizes, numbers, and locations of the vents.
The simulated results from CFD show that while considering the engine heat and the opening of Vent3, increasing the size of the vent can decrease the minimum velocity by 50% in Side regions but not in Corner regions. On the other hand, when the humidity inside is considered as well, the maximum relative humidity in Side and Corner regions are less 34.9% and 1%, respectively, as compared to the original vent. Different locations and numbers of vents and also engine heat effects are also discussed. While opening Vent3 and Vent6 at the same time, the performance of the minimum velocities in Corner and Side regions are about 19.4% and 50%, respectively, better than opening Vent3 only. However, the maximum relative humidity increases in both Corner and Side regions. Thus, increasing the vent size is a better choice to reduce the moisture inside the vehicle headlamps.

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