傳統戰機進氣道具有分流隔板來排除低動能之邊界層氣流，然而此種設計將會導致進氣道結構複雜、重量增加、阻力上升及雷達散射截面（Radar Cross Section, RCS）提高等缺點，因此新型進氣道無分流隔板超音速進氣道(Diverterless Supersonic Inlet, DSI)移除分流隔板設計，利用三維壓縮面(Bump)設計將邊界層氣流排開，搭配前掠外罩管道及管道組成，大幅降低進氣道重量及雷達散射截面。
本研究以F-35戰機前機身為幾何模型基礎，整合三維壓縮面、外罩與Y型管道，建立完整的進氣道模型，本研究提出全新外罩設計方法，根據三維壓縮面模擬結果將震波聚焦點連線並形成一陣波聚焦點曲面，並在參數化設計選擇出外罩角度。管道設計部份，為提升進氣道整體氣動性能，本研究運用計算流體力學（CFD）模擬搭配伴隨算子方法（Adjoint Method），並設計兩種不同的優化策略，對Y型管道進行多次外型優化，以提升總壓恢復係數為目標，並將管道優化結果安裝回具有前機身外型進行模擬，模擬結果顯示，經優化後的進氣道在設計點（M=2）模擬下，其總壓恢復係數明顯提升，總壓失真與速度不均勻度皆有效降低，有效提升進氣道整體性能。
優化後的DSI進氣道在設計點外模擬結果皆顯示出，在不同馬赫數、俯仰角，側滑角及阻塞比下皆維持著良好性能，本研究證明伴隨方法可有效改善DSI性能，並為未來進氣道優化與隱身戰機設計提供新的設計方法。

Conventional fighter aircraft inlets typically employ boundary layer diverters to remove low-momentum flow near the fuselage. While this design may be effective in its primary function, it can introduce negative consequences such as increased structural complexity, weight, drag, and Radar cross-section (RCS). To overcome these drawbacks, Diverterless supersonic inlet (DSI) design eliminates the diverter and utilizes a three-dimensional compression surface to redirect the boundary layer. Combined with a forward-swept cowl and internal duct, DSI configuration significantly reduces inlet weight and RCS, offering advantages in aerodynamic and stealth performance.
This study adopts F-35 forebody to as the geometric foundation to construct a complete DSI model integrating a three-dimensional compression surface, cowl, and Y-duct. A novel cowl design methodology is proposed, in which shock focal points from compression surface simulations are connected to form a focal point surface, guiding the cowl angle through parametric design. For the Y-duct, computational fluid dynamics (CFD) and the adjoint method are applied for multiple shape optimizations targeting maximum total pressure recovery at the aerodynamic interface plane (AIP). The optimized duct is reintegrated into the inlet, and Mach 2 simulations show a clear improvement in total pressure recovery at the AIP. Furthermore, total pressure distortion is reduced and velocity uniformity is enhanced. Off-design simulations confirm robust performance across various Mach numbers, angles of attack, sideslip angles, and blockage ratios, validating the effectiveness of the proposed optimization approach for future DSI and stealth inlet design.

[1]D. R. K. Scharnhorst, “An Overview of Military Aircraft Supersonic Inlet Aerodynamics,” AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Nashville, 2012.
[2] A.H.Sacks ,J.R.Spreiter, “Theoretical Investigation of Submerged Inlets at Low Speed”, NACA TN 2323, National Advisory Committee for Aeronautics, 1951.
[3] M.C.Gridley, S.H.Walker, “Inlet and Nozzle Technology for 21st Century Fighter Aircraft, ” International Gas Turbine and Aexoengine Congress at Exhibition, 1996.
[4] P. Y. Ufimtsev, “Elementary edge waves and the physical theory of diffraction”, Electromagnetics, vol. 11, no. 2, pp. 125-160, 1991.
[5] H.Ling, R.C.Chou, S.W.Lee,“Shooting and bouncing rays: Calculating the RCS of an arbitrarily shaped cavity”, IEEE Transactions on Antennas and propagation, vol. 37, no. 2, 1989.
[6] J. W. Hamstra, B.N. McCallum, “ Tactical aircraft aerodynamic integration”, Encyclopedia of aerospace engineering, 2010.
[7] Rasoul Askari and Mohammad Reza Soltani, “Symmetric and Asymmetric Performance Investigation of a Diverterless Supersonic Inlet,” AIAA JOURNAL, vol. 60, no. 5, pp. 2850–2859, May 2022.
[8] G.C. Oates, Aircraft propulsion systems technology and design, AIAA EDUCATION SERIES, 1989.
[9] J. Seddon, E. L. Goldsmith,'' Intake Aerodynamics'', AIAA Education Series, 1999.
[10] J. E. Hawkins, “YF-16 Inlet Design and Performance”, Journal of Aircraft, vol. 13, no. 6, pp. 436-441, 1976.
[11] W.Brown, R.G.Huff, P.C.Simon, “ Performance of external compression bump inlet at Mach numbers of 1.5 and 2.0”, NACA RM E56L19, National Advisory Committee for Aeronautics, 1957.
[12] J.W. Hamstra ,T.G. Sylvester, “System and Method for Diverting Boundary Air”, United States 專利, 1998.
[13] E. Hehs, “JSF Diverterless Supersonic Inlet ” , 2000. [ 線上]. Available: http://www.codeonemagazine.com/article.html?item_id=58.
[14] J.W. Hamstra ,T.G. Sylvester, “System and Method for Diverting Boundary Air”, United States 專利, 1998.
[15] C. Wiegand, “F-35 air vehicle technology overview”, Aviation Technology, Integration, and Operations Conference, 2018.
[16] 黃偉聖, “錐形流推導之凸起物外型暨超音速進氣口,” 成功大學碩士論文, 2021.
[17] 林傑脩, “側向布局超音速進氣口空氣動力特性研究,” 成功大學碩 士論文, 2022.
[18] 蕭又升, “機首側向佈局蚌式超音速進氣道之氣動力與匿蹤性能,” 成功大學碩士論文, 2023.
[19] R. Askari and M. R. Soltani, “Numerical Simulation of a Y-Shaped Diverterless Supersonic Inlet,” J Aircr, vol. 60, no. 4, pp. 1007–1016, Jul. 2023.
[20] 蔡鎮壕, “機腹布局之無分流隔板超音速進氣道設計暨氣動與匿蹤特性模擬分析,” 成功大學碩士 學位論文, 2022.
[21] 陳震宇, “匿蹤戰機外型設計對雷達散射截面分析,” 2020.
[22] 謝雪明, 郭榮偉, “無隔道進氣道 RCS 特性實驗研究”, 航空學 報, vol. 27, no. 2, pp. 193-197, 2006.
[23] J.Slater, “ Design and analysis tool for external-compression supersonic inlets”, 50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, p. 16, 2012.
[24] M. R. Soltani, J. Sepahi Younsi, and A. Daliri, “Performance investigation of a supersonic air intake in the presence of the boundary layer suction,” Proc Inst Mech Eng G J Aerosp Eng, vol. 229, no. 8, pp. 1495–1509, Jun. 2015.
[25] M. Abedi, R. Askari, and M. R. Soltani, “Numerical simulation of inlet buzz,” Aerospace Science and Technology, vol. 97, Feb. 2020.
[26] Z. Zhang and K.-Y. Lum, “S-Shaped Inlet Design Optimization Using the Adjoint Equation Method,” 2006.
[27] Z. Altaf, M. I. Babar, and S. Salamat, “Multi-objective shape optimization of doubly offset serpentine diffuser using Adjoint method,” Int J Heat Fluid Flow, vol. 102, Aug. 2023.
[28] A. Sóbester, “Tradeoffs in jet inlet design: A historical perspective”, Journal of aircraft, vol. 44, no. 3, pp. 705-717, 2007.
[29] J. D. Mattingly, "Elements of Gas Turbine Propulsion", McGraw-Hill, 1995.
[30] J. D. Anderson, “Fundamentals of Aerodynamics Fifth Edition,” 2009.
[31] K. Oswatitsch, “Pressure Recovery for Missiles with Reaction Propulsion at High Supersonic Speeds (The Efficiency of Shock Diffusers),” 1980.
[32] O. Özcan, F. O. Edis, A. R. Asian, İ Pinar," Inverse Solutions of the Prandtl-Meyer Function", J. Aircraft, Vol. 31, No. 6: Engineering Notes, 1994.
[33] J.F.Connors, R.C.Meyers, "Design Criteria for Axisymmetric and Two Dimensional Supersonic Inlets and Exits", NACA, 1956.
[34] F. R. Menter, “Two-equation eddy-viscosity turbulence models for engineering applications,” AIAA Journal, vol. 32, no. 8, pp. 1598–1605, Aug. 1994.
[35] H. Mendis, “"Better meshing using ANSYS Fluent Meshing https://www.linkedin.com/pulse/better-meshing-using-ansys-fluent 212 hashan-mendis,” 2018.
[36] H. G. Tao, H. X. Chen, J. L. Xie, and Y. P. Hu, “An alternative approach to quantifying fluid flow uniformity based on area-weighted average velocity and mass-weighted average velocity,” Energy Build, vol. 45, pp. 116–123, Feb. 2012.
[37] A.Ferri, L.M.Nucci, “ The origin of aerodynamic instability of supersonic inlets at subcritical conditions ” , National Advisory Commitee for Aeronautics, vol. NACA-RM-L50K30, 1951.
[38] C. C. Lee and C. Boedicker, “Subsonic Diffuser Design and Performance for Advanced Fighter Aircraft,” Oct. 1985.