[[alternative]]以替代法進行翼胴合一飛機外形最佳化之研究

碩士[[abstract]]隨著時代的改變，各式各樣的飛機被發展出來，像是翼胴合一飛機，雖然它的概念很早就被提出，不過最近開始被更加重視了。翼胴合一飛機的機身和機翼是合為一體的，因此可以提供飛機較高的升力。在本研究之前，學長已經做過了許多關於翼胴合一飛機的空氣動力分析，不過尚未考慮到發動機部分。我們使用現有之飛機外形檔，再利用Pro/E 創造發動機並加在飛機的外形上，接著使用ANSYS 網格技術建造網格，並使用FLUENT 模擬出翼胴合一飛機在巡航時，不同派龍高度和攻角對其升力係數、阻力係數和升阻比的影響。有了這些基本數據後，就可以利用最佳化工具找到最佳的派龍高度及攻角。本文使用之最佳化工具是替代方法，替代方法是由許多不同的模型所組成，其中之一是Kriging model，我們正是用它來尋找最佳答案。為了要知道最佳化的使用方式正不正確，在翼胴合一飛機加發動機尋找最佳派龍高度及攻角的研究前，先預測了翼胴合一飛機在沒有發動機的情況下，使用Kriging model 找飛機巡航時的最佳攻角，在本研究中，我們只考慮升阻比，意即利用已知攻角的升阻比來預測最大升阻比的攻角，當預測的結果符合期望後，才開始飛機加發動機後的研究。在加發動機的案例中，吾人使用了兩種不同的方式去尋找最佳值，一種是先找派龍的最佳高度再找飛機的最佳攻角，另一種是直接預測出兩個值的最佳答案，結果顯示一次預測兩個值的案件比另一個有效率，且有更佳的結果，這也顯示出Kriging model 的優點，並證明吾人已經可以同時預測出兩個以上的最佳值。[[abstract]]In pace with the modern airplane development motivated by fuel efficiency and environmental conservation, many different aircraft configurations and design concepts are created in last two decades to accommodate these challenges. Blended Wing Body aircrafts (BWB) are created for the same reason, and remains to be one of the most promising flight vehicle concepts for future generations to come. But this plane are seldom seen, people are still study its aerodynamic analysis at the beginning stage, moreover the aerodynamic performance of BWB with its engines on. In this research, based on previous works at Tamkang, we construct geometry model first and now this BWB is with engine added on. Then, software ANSYS is implemented to generate different types of mesh, such as structured, unstructured, and hybrid grids. The flow solver routine with proper turbulence model selection is first tested on our previous UAV, M-6 wing, and BWB configurations, and then this simulation routine is also extended to the incompressible take-off speed and 0.85 Mach cruise conditions. After that, we select the surrogate model to find the BWB optimum angle of attack (AOA) and vertical height for engine positions. The surrogate model is a relatively new method for optimum engineering design, which is especially suited for CFD optimization computation and contains several different modules, and the model we select is the Kriging model. Without spend too much effort on the time consuming CFD simulation for every different AOA and engine positions, it allows us to find the best possible configuration conditions from a mere of about ten properly chosen design of experiment (DOE) cases. This model is verified by first predicting the best AOA value for BWB without engines, and a normalized optimization parameter or objective function is created, which composed of both the lift and drag coefficients. Thus we can predict the optimum AOA for BWB and its engine vertical positions. After the predicting value is achieved, new engine position geometry will be generated according to the surrogate model prediction. Results show that the close agreement between our Kriging model prediction and CFD computation represent a first triumph in the surrogate model implementation, and this could imply tremendous saving in future aerodynamic simulation in the airplane design phases.[[tableofcontents]]Abstract III Contents V List of Figures VII List of Tables XIV Nomenclature XVII Chapter 1 Introduction 1 Chapter 2 Literature Review 5 Chapter 3 Numerical Modeling 19 3-1 Geometry Model Construction 19 3-2 Grid Generation 22 3-3 Flow Solver 25 3-4 Turbulence Modeling 30 3-5 Verification 33 3-6 Optimization 41 Chapter 4 Results and Discussion 44 4-1 BWB without the engine 44 4-2 The Optimal Engine Position and AOA Prediction in Two Steps 52 4-3 The Optimal Engine Position and AOA Prediction in One Step 59 Chapter 5 Conclusions 81 References 83 Appendix 88 List of Figures Figure 1-1 BWB aircraft of NASA 2 Figure 1-2 Typical joined wing aircraft with two alternate tails 2 Figure 2-1 Genesis of the BWB concept 6 Figure 2-2 Interior arrangement of BWB passenger cabin 7 Figure 2-3 BWB cabin egress flow patterns 8 Figure 2-4 Sketches of joined wing configuration ranging through each design variable 9 Figure 2-5 Standard box wing 10 Figure 2-6 Typical engine component parts 11 Figure 2-7 The objective function and the Kriging model 16 Figure 2-8 Procedure of multi-objective global exploration 17 Figure 3-1 Blended-Wing-Body geometry model 19 Figure 3-2 BWB configuration and engines location 20 Figure 3-3 The rear view of engine and pylon relative positions 21 Figure 3-4 Enlargements of the engine and pylon location 21 Figure 3-5 BWB’s hybrid mesh 23 Figure 3-6 BWB’s structure mesh 24 Figure 3-7 Y plus distribution with CFX solver 28 Figure 3-8 Y plus distribution with FLUENT solver 28 Figure 3-9 The sets of FLUENT in ANSYS 29 Figure 3-10 Turbulence modeling selection of FLUENT in ANSYS 32 Figure 3-11 UAV’s configuration and its mesh 33 Figure 3-12 Boundary layer setting in GAMBIT 34 Figure 3-13 Unstructured mesh’s wall y plus distribution 35 Figure 3-14 Hybrid mesh’s wall y plus distribution 36 Figure 3-15 L/D comparison of BWB at M=0.85 38 Figure 3-16 Projection plane of M6 wing 39 Figure 3-17 Near structure mesh of the M6 wing 39 Figure 3-18 Pressure coefficients at section y/b= (a) 0.2 (b) 0.4 (c) 0.65 (d) 0.8 (e) 0.9 (f) 0.95 (g) 0.99 41 Figure 4-1 L/D comparison between Kriging prediction of AOA=0°, 1°, 2°, 3°, 4°, 5° and FLUENT solver for BWB with no engine 47 Figure 4-2 L/D comparison between Kriging prediction of AOA=0°, 1°, 1.5°, 2°, 3°, 4°, 5° and FLUENT solver for BWB with no engine 48 Figure 4-3 L/D comparison between Kriging prediction of AOA=0°, 1°, 2°, 3°, 4° and FLUENT solver for BWB with no engine 49 Figure 4-4 L/D comparison between Kriging prediction of AOA=1°, 1.5°, 2°, 3°, 4° and FLUENT solver for BWB with no engine 50 Figure 4-5 L/D comparison between Kriging prediction of AOA=1°, 1.5°, 2°, 3°, 4°,5° and FLUENT solver for BWB with no engine 51 Figure 4-6 L/D comparison between Kriging prediction of AOA=1°, 2°, 3°, 4°,5° and FLUENT solver for BWB with no engine 52 Figure 4-7 The streamline for BWB with no engines 58 Figure 4-8 The streamline for BWB with engine position is 3m 58 Figure 4-9 Pressure contour for BWB at 0.85 Mach and 2.09 degree with engine position of 2.97m. 64 Figure 4-10 Mach contour for BWB at 0.85 Mach and 2.09 degree with engine position of 2.97m. 64 Figure 4-11 Upper surface Mach contour comparison for BWB without engine at different AOA: (a) 0 degree (b) 1.7 degree 67 Figure 4-12 Lower surface Mach contour comparison for BWB without engine at different AOA: (a) 0 degree (b) 1.7 degree 67 Figure 4-13 Side-view Mach contour comparison for BWB without engine at different AOA: (a) 0 degree (b) 1.7 degree 68 Figure 4-14 Upper surface pressure contour comparison for BWB without engine at different AOA: (a) 0 degree (b) 1.7 degree 68 Figure 4-15 Lower surface pressure contour comparison for BWB without engine at different AOA: (a) 0 degree (b) 1.7 degree 69 Figure 4-16 Side-view pressure contour comparison for BWB without engine at different AOA: (a) 0 degree (b) 1.7 degree 69 Figure 4-17 Upper surface Mach contour comparison for BWB at 2 degree AOA: (a) without engine (b) with engine 70 Figure 4-18 Lower surface Mach contour comparison for BWB at 2 degree AOA: (a) without engine (b) with engine 70 Figure 4-19 Side-view Mach contour comparison for BWB at 2 degree AOA: (a) without engine (b) with engine 71 Figure 4-20 Upper surface Mach contour comparison for BWB at 2 degree AOA: (a) without engine (b) with engine 71 Figure 4-21 Lower surface Mach contour comparison for BWB at 2 degree AOA: (a) without engine (b) with engine 72 Figure 4-22 Side-view Mach contour comparison for BWB at 2 degree AOA: (a) without engine (b) with engine 72 Figure 4-23 Upper surface Mach contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 73 Figure 4-24 Lower surface Mach contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 73 Figure 4-25 Side-view Mach contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 74 Figure 4-26 Upper surface pressure contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 74 Figure 4-27 Lower surface pressure contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 75 Figure 4-28 Side-view pressure contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 75 Figure 4-29 Engine inlet pressure contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 76 Figure 4-30 Engine nozzle pressure contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 76 Figure 4-31 Engine longitudinal centerline pressure contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 77 Figure 4-32 Engine inlet temperature contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 77 Figure 4-33 Engine nozzle temperature contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 78 Figure 4-34 Engine longitudinal centerline temperature contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 78 Figure 4-35 Engine inlet velocity contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 79 Figure 4-36 Engine nozzle velocity contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 79 Figure 4-37 Engine longitudinal centerline velocity contour comparison for BWB at 2.09 degree AOA and 1.22m pylon height: (a) treat engine as a tube (b) include engine inlet/nozzle boundary conditions 80 List of Tables Table 2-1 The parameters in a gas generator 11 Table 3-1 The L/D comparison due to different meshes and code application 27 Table 3-2 The L/D comparison due to different turbulence models and meshes 33 Table 3-3 The L/D comparison due to different meshes 34 Table 3-4 Lift and drag coefficient of BWB without engines at M=0.85 36 Table 3-5 L/D comparison of BWB at M=0.85 37 Table 4-2 L/D comparison between Kriging prediction of AOA=0°, 1°, 1.5°, 2°, 3°, 4°, 5° and FLUENT solver for BWB with no engine at AOA=1.7° 47 Table 4-3 L/D comparison between Kriging prediction of AOA=0°, 1°, 2°, 3°, 4° and FLUENT solver for BWB with no engine at AOA=1.7° 48 Table 4-4 L/D comparison between Kriging prediction of AOA=1°, 1.5°, 2°, 3°, 4° and FLUENT solver for BWB with no engine at AOA=1.7° 49 Table 4-5 L/D comparison between Kriging prediction of AOA=1°, 1.5°, 2°, 3°, 4°, 5° and FLUENT solver for BWB with no engine at AOA=1.7° 50 Table 4-6 L/D comparison between Kriging prediction of AOA=1°, 2°, 3°, 4°, 5° and FLUENT solver for BWB with no engine at AOA=1.7° 51 Table 4-7 BWB''s CD and L/D for engine at different vertical positions 53 Table 4-8 BWB''s CD2 and (L/D- L/D0)2 for engine at different vertical positions 53 Table 4-9 BWB''s f for engine at different vertical positions 54 Table 4-10 BWB''s CD, L/D, and f for engine at different vertical positions for 7 data 55 Table 4-11 BWB''s CD, L/D, and f for engine at different AOA 56 Table 4-12 BWB''s L/D at 2 degree AOA 57 Table 4-13 BWB''s CD and L/D in different AOA and engine at vertical positions 59 Table 4-14 BWB''s (L/D-L/D0)2, CD2 and CD2×C in different AOA and engine at vertical positions 60 Table 4-15 BWB''s f in different AOA and engine at vertical positions 61 Table 4-16 Comparison engine''s position, AOA and f in two different methods 63 Table 4-17 The CL, CD and L/D value in different boundary condition 65[[note]]學號: 600430416, 學年度: 10