良好的進氣道需要有捕獲氣流、壓縮空氣並提供高總壓恢復的氣流以利發動機正常運作，因此進氣道前端的進氣口(Inlet aperture)幾何成為了進氣道氣動力構型初步設計上的重要研究主題。傳統進氣口採用邊界層隔板(Diverter)以避免進氣道吸入低能量的氣流，然而該設計亦使得重量及維護成本增加，現役五代戰機為了降低維護成本，並且仍維持優良的氣動性能及提升匿蹤能力，採用了一種稱作無邊界層隔板超音速進氣道的構型(Diverterless supersonic inlet, DSI)，所謂DSI進氣道為一種在進氣口安裝某三維幾何面之先進進氣道設計，該三維幾何面稱作為凸起物(Bump)，是一種以錐形流(Conical flow)為基礎流場進行流線追蹤生成的適型幾何，此進氣口能有效地在壓損最小下將邊界層內低能量氣流排開。如何設計DSI之凸起物以及DSI進氣口的幾何和性能分析為本研究重要的課題，本研究以馬赫數2.0之錐形流為進氣道設計點設計三維等熵(Isentropic)凸起物表面，以計算流體力學工具(CFD)模擬設計點上及設計點外凸起物之空氣動力特性，並再以模擬結果之流場為基礎設計DSI初步構型，使用CFD分析其性能。本研究的結果表明，以錐形流推導之凸起外型能夠在設計點上及設計點外將氣流壓縮、導開邊界層內的低能量氣流並且維持良好的總壓恢復能力，凸起物的高度差異影響了總壓恢復程度及阻力大小；以凸起物構型設計之DSI，其不同的尺寸造成震波結構的改變，使其氣流捕獲量及總壓恢復有所不同，阻力則受到凸起物幾何影響。DSI在設計點上及設計點外接滿足進氣道運作的基本需求，實現以錐形流推導之三維凸起物幾何為構型的進氣口初步設計。

This study proposed the design and aerodynamic analysis of diverterless supersonic inlet (DSI). The DSI contains two main structures, one is a three-dimensional bump, and the other is the cowling. This study firstly investigated the flow field of different bump geometries. And secondly, this study analyzed the performance of the DSI. The bump geometries were designed by tracing streamlines in the conical flow, and the streamlines were released from two different locations, resulting in height differences for the bumps. This study also designed the transition from the bump to the internal duct, transition shoulder (T.S.). The T.S. was installed at the end of the bumps, and the shape of the T.S. was modified by adjusting the peak slope. This study provided two different T.S. shapes, and with the two different bump heights, there were four variant bumps to be investigated. The four variant bumps were mounted on the DSI, and the flow field of the bumps determined the size of the DSI cowling, causing discrepancies in the capture area. Finally, the simulation showed that the height of the DSI bumps and the modification of the T.S. contributed to different pressure gradients, causing various extents of the surface flow diversion and the drag. The sizes and the shaps of the DSI cowling influenced the structure of the shock system, resulting in different flow ratios, and the flow ratio to the total pressure recovery was highly related. All DSIs had a total pressure recovery higher than 90%.

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