簡易檢索 / 詳目顯示

回結果列表
研究生： 陳彥伯
Chen, Yen-Po
論文名稱： 雷諾數對無人飛行載具之渦流狀態演變之影響
Effects of Reynolds Number on the State Switch of Vortex System of Unmanned Combat Arial Vehicle
指導教授： 苗君易
Miau, Jiun-Jih
學位類別： 碩士
Master
系所名稱： 工學院 - 航空太空工程學系
Department of Aeronautics & Astronautics
論文出版年： 2024
畢業學年度： 112
語文別： 英文
論文頁數： 129
中文關鍵詞： 無人戰鬥飛行載具 、SACCON 、流場可視化 、雷諾數效應
外文關鍵詞： UCAV, SACCON, flow visualization, Reynolds number effect
相關次數： 點閱：104  下載：12 
分享至:
查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報

    • 隨著戰爭型態演變，戰場上的飛行載具也逐漸朝著匿蹤化以及無人化的方向演進，統稱為無人戰鬥飛行載具(UCAV)。北約組織所提出的SACCON構型，便是順應此趨勢所催生的研究產物。在本實驗室幾位學長姐的研究中，已經初步了解SACCON構型在低雷諾數情形下的基本流場結構。儘管如此，在流場可視化的結果中，仍然有著與更高雷諾數的研究文獻中有所出入的部分。再者，近期的俄烏戰爭中，飛行載具亦出現小型化的趨勢，因此對於UCAV的研究，必須有著大範圍雷諾數跨度的現象探討。本研究首先必須進一步釐清在前人的研究中所遺留下來的問題。對SACCON的基本流場有更深入的了解後，便會進一部探討雷諾數效應對於整個SACCON構型之渦流系統狀態演變之影響。本研究在循環式水槽以及開放式風洞中使用多種流場可視化方法，如油膜法、染液注射法以及點墨法，試圖將各個雷諾數下的流場清晰呈現以便分析。在歸仁低速開放式風洞中，亦進行壓力係數量測的實驗，藉由更廣的壓力孔分佈，試圖看到更細微的流場現象。
    本研究主要使用數個大小不同的SACCON模型進行實驗，以及一個Delta-S模型來和SACCON的油膜可視化實驗對比。對比的結果顯示，SACCON模型上銳形翼前緣以及鈍形翼前緣交界的凹陷處，會對於翼表上翼展方向的附著流以及inner vortex產生增強作用，也藉由此實驗進一步確認inner vortex是由翼前緣分離的剪切層、翼展方向的附著流以及上游apex vortex的渦量傳遞而形成。後續的流場可視化實驗以及壓力量測實驗所得到的結果顯示，SACCON構型在低雷諾數下的流場拓撲結構和高雷諾數的文獻有著很大的差異。在過往以及本次實驗中所看到的inner vortex現象，與文獻中的thickness vortex現象有著很大的不同。在過去視流實驗裡，inner vortex一度被認為與thickness vortex是相同現象，但在本次壓力量測實驗中，隨著雷諾數升高，inner vortex又會逐漸消失。綜上所述，本研究透過在不同數量級的雷諾數下進行實驗，確立了SACCON構型在低雷諾數下的重要流場特徵。隨著雷諾數升高，象徵低雷諾數流場特徵的inner vortex現象會趨於不明顯，意味著當雷諾數改變，也會深遠地影響SACCON上翼面渦流狀態演變(State Switch)以及參與其中的流場結構。

    As the pattern of modern warfare keep evolving, the airborne vehicles on the battlefield are gradually evolving towards stealth and unmanned capabilities, which is collectively referred to as Unmanned Combat Aerial Vehicles (UCAVs). The SACCON configuration proposed by the NATO organization is an outcome that aligns with this emerging trend. While several research that provide preliminary understanding about the SACCON flow topology under low Reynolds number has been done in our lab previously, some unknown discrepancies remain when compared to the literature of higher Reynolds numbers. Furthermore, in the recent Russia-Ukraine conflict, there has also been a trend towards downsizing of airborne vehicles. As a result, aerodynamic research on UCAVs must involve a comprehensive investigation into a wide range of Reynolds numbers. The first step of this research is to clarify the questions remain previously. After having a better understanding of basic SACCON flow characteristic, Reynolds number effect on the state switch of vortex system of SACCON will be investigated. In this research, various visualization techniques such as oil flow, dye injection as well as ink dot is applied to bring a clearer picture of flow structure under a range of Reynolds number. For the low-speed open type wind tunnel in ASTRC, pressure coefficient measurement is also conducted. Through a wider distribution of pressure taps, more detailed phenomena on SACCON are expected to be depicted.
    In the experiment, several SACCON models with different sizes is applied, as well as a Delta-S model in comparison with the oil-flow result of SACCON. The outcome of the comparison indicates that the concave topology at the junction between sharp and blunt leading-edge section has a strengthening effect to the spanwise component of the attached flow as well as the inner vortex. Furthermore, we finally confirm that the formation of inner vortex is attributed to the interaction between the separated shear layer, the spanwise attached crossflow as well as the vorticity transportation from the apex vortex. The following flow visualization and pressure coefficient measurement all indicate a significant difference of the SACCON flow topology between low Reynolds number (this research) and high Reynolds number (literature). The inner vortex we saw in the experiment has a huge difference from the thickness vortex mentioned in the literature, which was once viewed as the same phenomena in the past. From the result of pressure coefficient measurement, the pressure coefficient variation that represent the inner vortex structure will be gradually suppressed as Reynolds number increased to a higher level. In summary, a clearer picture of the SACCON flow characteristic under low Reynolds number has been established in this research. The inner vortex structure which represents the low Reynolds number flow characteristic will be gradually suppressed as Reynolds number increases. In other words, changes in Reynolds number significantly affect the state switch progress above SACCON surface as well as the flow structures involved.

    中文摘要 i 英文摘要 iii 致謝 v Outline vi List of Figures ix List of Tables xiv Nomenclature xv Chapter1 1 Introduction 1 1.1 Background 1 1.2 Objective 1 1.3 Literature Survey 3 1.3.1 Delta Wing Vortical Flow Structure 3 1.3.2 Effect of Boundary Layer Transition 13 1.3.3 CFD Modeling of SACCON Vortical Flow Structure 17 1.3.4 Formation and Identity of Inner Vortex Structure 22 1.4 Research Approach 27 1.4.1 Effect of Concave Topology to the Onset of Inner Vortex 27 1.4.2 Reynolds Number Effect to State Switch Process 28 Chapter2 29 Instruments and Experimental Setup 29 2.1 Models 29 2.1.1 SACCON Models for Flow Visualization 29 2.1.2 Delta-S Model for Flow Visualization 31 2.1.3 Large SACCON Model for Pressure Data Acquisition 32 2.2 Low-Speed Recirculating Water Channel 33 2.3 Low-Speed Open-Jet Wind Tunnel 34 2.4 Low-Speed Open Type Wind Tunnel 35 2.5 Experiment Apparatus 36 2.5.1 Laser Level Meter 36 2.5.2 Visualization Apparatus 37 2.5.3 Four-Bar Linkage Mechanism 38 2.5.4 Pitot-Static Pressure Tube 39 2.5.5 Pressure Transducer 40 2.5.6 Pressure Calibrator 40 2.5.7 Data Acquisition System 41 Chapter3 43 Experimental Method and Data Analysis 43 3.1 Methodology 43 3.1.1 Oil-Flow Visualization 43 3.1.2 Dye-Injection Visualization 44 3.1.3 Ink-Dot Visualization 46 3.1.4 Surface Pressure Coefficient Measurement 47 3.2 Parameter Analysis 47 3.2.1 Reynolds Number 47 3.2.2 Pressure Coefficient 48 3.2.3 Pressure Fluctuation 48 Chapter4 50 Results and Discussion 50 4.1 Oil-Flow Results on SACCON Model 50 4.2 Oil-Flow Results on Delta-S Model 51 4.3 Dye-Injection Results on SACCON Model 53 4.3.1 Dye Injection Result at Re=4.24×103 53 4.3.2 Dye Injection Result at Re=8.12×103 58 4.4 Ink-Dot Results on SACCON Model 62 4.5 Summary of Flow Visualization Results 67 4.5.1 Effect of Concave Topology 67 4.5.2 Reynolds Number Effect 67 4.6 Surface Pressure Test on SACCON Model 70 4.6.1. Time Averaged Cp and Cp Fluctuation 71 4.6.2. Comparison with Chen’s Result 102 4.7 Summary of SACCON Flow Topology 103 Chapter5 105 Conclusions and Suggestions 105 5.1 Conclusions 105 5.2 Suggestions 108 References 109

    1. Sepulveda, E. and H. Smith, Technology challenges of stealth unmanned combat aerial vehicles. The Aeronautical Journal, 2017. 121(1243): p. 1261-1295.
    2. Gursul, I., Vortex flows on UAVs: Issues and challenges. The Aeronautical Journal, 2016. 108(1090): p. 597-610.
    3. Cummings, R. and A. Schütte. An integrated computational/experimental approach to UCAV stability & control estimation: overview of NATO RTO AVT-161. in 28th AIAA Applied Aerodynamics Conference. 2010.
    4. Loeser, T., D. Vicroy, and A. Schuette. SACCON static wind tunnel tests at DNW-NWB and 14 x22 NASA LaRC. in 28th AIAA applied aerodynamics conference. 2010.
    5. Luckring, J.M. and O.J. Boelens. A unit-problem investigation of blunt leading-edge separation motivated by AVT-161 SACCON research. in NATO RTO Specialists Meeting AVT-189. 2011.
    6. Schütte, A., D. Hummel, and S.M. Hitzel. Numerical and experimental analyses of the vortical flow around the SACCON configuration. in 28th AIAA Applied Aerodynamics Conference. 2010.
    7. Vallespin, D., et al., Validation of vortical flow predictions for a UCAV wind tunnel model. 2010.
    8. Zimper, D. and D. Hummel, Analysis of the Transonic Flow Around a Unmanned Combat Aerial Vehicle Configuration. Journal of Aircraft, 2018. 55(2): p. 571-586.
    9. Chen, Y.-H., 複合型翼前緣無人飛行載具之渦流系統研究, in Institute of Aeronautics and Astronautics. 2022, National Cheng Kung University.
    10. Anderson, J., EBOOK: Fundamentals of Aerodynamics (SI units). 2011: McGraw hill.
    11. Hummel, D., Experimental investigation of the flow on the suction side of a thin delta wing. 1981.
    12. Nelson, R.C. and A. Pelletier, The unsteady aerodynamics of slender wings and aircraft undergoing large amplitude maneuvers. Progress in Aerospace Sciences, 2003. 39(2-3): p. 185-248.
    13. Payne, F., et al., Visualization and wake surveys of vortical flow over a delta wing. AIAA journal, 1988. 26(2): p. 137-143.
    14. Earnshaw, P., An experimental investigation of the structure of a leading-edge vortex. 1961.
    15. Woodiga, S.A. and T. Liu, Skin friction fields on delta wings. Experiments in Fluids, 2009. 47(6): p. 897-911.
    16. Lambourne, N. and D. Bryer, The bursting of leading-edge vortices-some observations and discussion of the phenomenon. 1961.
    17. Luckring, J. Reynolds number and leading-edge bluntness effects on a 65-deg delta wing. in 40th AIAA Aerospace Sciences Meeting & Exhibit. 2002.
    18. JM, L. Reynolds Number, Compressibility, and Leading Edge Bluntness Effects on Delta-Wing Aerodynamics. in 24th International congress of the aeronautical sciences. 2004.
    19. Erickson, G. Flow studies of slender wing vortices. in 13th Fluid and PlasmaDynamics Conference. 1980.
    20. Traub, L.W., S.F. Galls, and O.K. Rediniotis, Reynolds number effects on vortex breakdown of a blunt-edged delta. Journal of aircraft, 1996. 33(4): p. 835-837.
    21. Ghazijahani, M.S. and M.M. Yavuz, Effect of thickness-to-chord ratio on aerodynamics of non-slender delta wing. Aerospace Science and Technology, 2019. 88: p. 298-307.
    22. Hummel, D. Review of the second international vortex flow experiment (VFE-2). in 46th AIAA Aerospace Sciences Meeting and Exhibit. 2008.
    23. Coton, F., et al. Low speed wind tunnel characterization of the VFE-2 wing. in 46th AIAA Aerospace Sciences Meeting and Exhibit. 2008.
    24. Schütte, A. and H. Lüdeke, Numerical investigations on the VFE-2 65-degree rounded leading edge delta wing using the unstructured DLR TAU-Code. Aerospace Science and Technology, 2013. 24(1): p. 56-65.
    25. Crippa, S. and A. Rizzi. Numerical investigation of Reynolds Number effects on a blunt leading-edge delta wing. in 24th AIAA Applied Aerodynamics Conference. 2006.
    26. Crippa, S. and A. Rizzi. Steady, subsonic CFD analysis of the VFE-2 configuration and comparison to wind tunnel data. in 46th AIAA Aerospace Sciences Meeting and Exhibit. 2008.
    27. Fritz, W., Numerical simulation of the peculiar subsonic flow-field about the VFE-2 delta wing with rounded leading edge. Aerospace Science and Technology, 2013. 24(1): p. 45-55.
    28. Konrath, R., et al. Analysis of PSP results obtained for the VFE-2 65° delta wing configuration at sub-and transonic speeds. in 44th AIAA Aerospace Sciences Meeting and Exhibit. 2006.
    29. Hummel, D., Effects of boundary layer formation on the vortical flow above slender delta wings. Enhancement of NATO Military Flight Vehicle Performance by Management of Interacting Boundary Layer Transition and Separation, 2004.
    30. Hövelmann, A., Analysis and control of partly-developed leading-edge vortices. 2016, Technische Universität München.
    31. Roosenboom, E.W.M., et al., Stereoscopic Particle Image Velocimetry Flowfield Investigation of an Unmanned Combat Air Vehicle. Journal of Aircraft, 2012. 49(6): p. 1584-1596.
    32. Hitzel, S.M., et al., Vortex development on the AVT-183 diamond wing configuration – numerical and experimental findings. Aerospace Science and Technology, 2016. 57: p. 90-102.
    33. Hövelmann, A., et al., AVT-183 diamond wing flow field characteristics Part 2: Experimental analysis of leading-edge vortex formation and progression. Aerospace Science and Technology, 2016. 57: p. 31-42.
    34. Hövelmann, A., F. Knoth, and C. Breitsamter, AVT-183 diamond wing flow field characteristics Part 1: Varying leading-edge roughness and the effects on flow separation onset. Aerospace Science and Technology, 2016. 57: p. 18-30.
    35. Gilliot, A., et al. Static and dynamic SACCON PIV tests, part I: forward flowfield. in 28th AIAA Applied Aerodynamics Conference. 2010.
    36. Konrath, R., et al. Static and dynamic SACCON PIV tests, part II: aft flow field. in 28th AIAA applied aerodynamics conference. 2010.
    37. Choi, C.-K. and D.-K. Kwon, Wind tunnel blockage effects on aerodynamic behavior of bluff body. Wind Struct Int J, 1998. 1(4): p. 351-364.
    38. 周牧廷, 翼身融合氣動力外型之渦流結構分析, in Institute of Aeronautics and Astronautics. 2020, National Cheng Kung University.
    39. Dong, P., J.-J. Miau, and A. Zoghlami, An experimental study about drag crisis phenomenon on teardrop model. Journal of Aeronautics, Astronautics and Aviation, 2019. 51(2): p. 141-157.
    40. Yu, J., T.-S. Leu, and J.-J. Miau, Investigation of reduced frequency and freestream turbulence effects on dynamic stall of a pitching airfoil. Journal of Visualization, 2017. 20: p. 31-44.
    41. Li, J.-Y., Improvement on a Blade of a Vertical-Axis Wind Turbine, in Institute of aeronautics and astronautics. 2013, National Cheng Kung University.
    42. Chen, L.-Y., J.-J. Miau, and Y.-H. Chen, Research of Reynolds Number Effect on Vortices Structures of Different Wing Geometry Configurations, in 中華民國航太學會學術研討會 AASRC Conference. 2021: Yunlin, Taiwan.
    43. Chen, Y.-H., et al., Comparison of flows around UCAV models of blunt apex, in 16th International Symposium on Advanced Science and Technology in Experimental Mechanics. 2021, Transport Publishing House: Hanoi, Vietnam. p. 46-51.
    44. 陳麗宇, 雷諾數效應對不同機翼幾何配置的渦流結構研究, in Institute of Aeronautics and Astronautics. 2021, National Cheng Kung University.
    45. Zimper, D. and M. Rein. Experimental and numerical analysis of the transonic vortical flow over a generic lambda wing configuration. in 32nd AIAA Applied Aerodynamics Conference. 2014.

    下載圖示 校內：立即公開
    校外：立即公開
    QR CODE