無人駕駛作戰飛機（UCAV）是當代設計飛機的一個趨勢，其中 SACCON 是北約科學界關注的研究之一，在低雷諾數（104~105）下，SACCON 模型上的渦流結構特徵與之前高雷諾數（≥ 106）下的研究有所不同。因此，為了研究低雷諾數下 SACCON模型和相關 UCAV 模型的流場拓撲結構，本研究在低速風洞和水洞中利用可視化油膜實驗和壓力測試進行。此外，本研究還歸納了擁有翼展弦前緣輪廓變化的 UCAV 模型流場特徵，以及鈍型翼前緣對模型的影響，所以更詳細的探討了具有鈍型翼前緣所形成複雜渦流系統的 UCAV 模型。
本研究運用四個模型來探討 SACCON 模型上的渦流結構，其中 Diamond wing、SACCON all Blunt 及 Diamond-S 為另外三個模型來輔佐研究的進行，並且和 SACCON
model 上的流場現象進行比較。在 α = 10˚和 Re = 7.12×104 時，從油流上可以觀察到，SACCON 模型上的流動結構以渦流和從中段鈍型翼前緣輪廓引導的附著流為主，這種附著流是被攻角和雷諾數影響，此現象也呈現在本研究所設計的模型 SACCON all Blunt 和 Diamond-S 上。從流場視覺化和壓力測量中依次觀察到，上游形成的渦流會受附著流影響在下游分支，而下游形成的渦流也會被附著流影響穩定性，然而，這種附著流的形成取決於翼前緣截面的厚度，如 Diamond wing 模型因其厚度太薄，就無法觀察到這種流動現象。綜上所述，本研究通過可視化實驗和表面壓力測量，探討相關 UCAV 模型在低雷諾數下的表現，展示了 SACCON 模型上複雜渦流系統的證據，並了解到流場拓撲結構變化取決於攻角、雷諾數效應和幾何效應，其中 UCAV 模型上的鈍型翼前緣截面即是主要探討的對象。

Unmanned Aerial Combat Aircraft (UCAV) is a popular modern aircraft design. The SACCON UCAV concept is a notable configuration developed by the NATO Science and Technology Organization (STO). Previous research at high Reynolds number (≥10^6) showed interesting vortical structures on the SACCON model. These features are recreated on the model at varied low Reynolds numbers (104 ~ 105). Oil-film visualization and pressure-testing measurement techniques are used on the UCAV models in a low-speed wind tunnel and water channel to study flow topology at low Reynolds numbers. This thesis showcases the flow field characteristics on UCAV models of spanwise-varying leading-edge contours and the blunt leading-edge effect on the models. The complex vortex system on UCAV models with the blunt leading-edge can be identified.

In this thesis, four models are tested. SACCON model is the main flow field research to be concentrated on. Other models, such as the diamond wing model, SACCON all Blunt and Diamond-S, are designed to compare their vortex structures with SACCON model’s one. Flow structures on SACCON model at α = 10˚and Re = 7.12 × 104 are dominated by vortices. The attached flow occurring at the mid-section with the blunt leading-edge contours was observed using oil-film visualization. This attached flow is varied with respect to the angle of attack and the Reynolds number. It presents on other models, such as the SACCON all Blunt and Diamond-S, as well. The attached flow affects the vortices forming upstream to branch downstream as well as the stability of the vortices forming downstream, which is observed from the flow visualization and pressure measurement. However, the formation of this attached flow depends on the thickness of the leading-edge cross-sectional profile. The diamond wing model is too slim to have observed this flow phenomenon in this thesis. In conclusion, this thesis shows evidence of the complex vortex system on SACCON model by flow visualization and surface pressure measurements at low Reynolds number using related UCAV models. The flow topology is dependent on the angle of attack, the Reynolds number, and the geometry.

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