翼胴合一飛行器之氣動力最佳化分析

近年飛機製造公司為了減少航空器運作成本而相繼推出強調省油與效率的飛機，翼胴合一飛行器即為在材料及技術的改進和航機大型化之外的一種解決方案。然而此型飛行器整體構造與傳統構型大不相同以致於對其製造、飛行乃至其它性能諸元皆無法掌握，故此種飛行器的相關性能研究成為近年許多研究單位的研究項目。本論文參考並仿製NASA所研發之X-48翼胴合一飛行器，以現有之計算流體力學軟體Fluent在0.85馬赫的高空巡航條件下，對其三維流場進行計算，比較不同翼尖裝置對其性能之影響。本論文所研究比較之翼尖裝置有一般常見之Winglet及一種較新穎的C-wing構型，此外本研究還針對另一翼胴合一飛行器研究論文所建立之飛機外形，進行計算並且互相比較。最後，本論文並對仿製的X-48外型進行最佳化計算及改進。挑選兩個飛機幾何參數並搭配使用CAD軟體、網格生程軟體、流場解算軟體以及自行寫作之程式碼，以期能改善模仿外形的表面流場、更動震波的位置及減少震波的強度，最終對飛行的效率提升了可觀的幅度。本研究結果可提供航空設計者對於航空飛機設計上靈感的啟發、增加設計工具的選用彈性、以及對於新型航空器的初步性能認識。在計算工具上更探討結構網格與非結構網格的優劣利弊和其對計算結果的影響差異，對於C-wing構型的利弊得失，也透過實際模型的預測，提供予飛機設計者作為重要的參考。

關鍵字

翼胴合一；翼尖裝置；最佳化

並列摘要

Aircraft manufacture companies have introduced new aircrafts with high fuel-efficiency to reduce the operation cost of flight vehicle in recent years; the blended-wing-body (BWB) aircraft is another solution besides the strategies of the improvement in structure/material and aircraft enlargement. But we cannot grasp the characteristics of manufacturing; flight efficiency, etc.; because the configuration of BWB is so different from the conventional one. So in recent years the related researches about this modern BWB aircraft become the topic of many research projects. This thesis refers and imitates the aircraft of NASA’s X-48, and then simulates the three-dimensional flow field with the flight condition of Mach 0.85 cruise at the high altitude using the existing computational fluid dynamics (CFD) software named “Fluent”. And then it evaluates the efficiency of flight performance with different wingtip devices. The wingtip devices of this research are the general common winglet and the novel configuration of C-wing. In addition, this research also enlists the BWB geometry from another fellow student, while computing and comparing with these different configurations. Another theme of this research is to do the optimisation study of the imitative X-48. We choose two values of twist angle parameter of the aircraft geometry, using software of CAD, grid generation, flow solver, and homemade programming codes. We expect that will improve the airflow on the surface of aircraft, move the position of shock wave, and weaken the strength of shock wave. Finally it increases the efficiency of aircraft for an apparent range. The result of this research will provide aircraft manufacture companies some inspiration of aircraft design, increased flexibility in the choice of design tools, and the preliminary understanding on flight performance of a new type of aircraft. We even investigate the pros and cons of structured and unstructured grid, and the difference in their simulated aerodynamic coefficients is quite large. One important finding of this study is that at least for our BWB configurations, the C-wing model does not seem to improve the cruise performance at all.

並列關鍵字

Blended-Wing-Body ； Wingtip Device ； Optimisation

參考文獻

[6] Ning, S. A. and Kroo, I., “Tip Extensions, Winglets, and C-wings: Conceptual Design and Optimization,” AIAA Paper 2008-7052.

[7] Fluent 6.3 User's Guide

[8] Cosentino, G. B., “CFD to Flight: Some Recent Success Stories of X-plane Design to Flight Test at the NASA Dryden Flight Research Center,” NASA Dryden Flight Research Center.

[10] Siouris, S. and Qin, N., “Study of the Effects of Wing Sweep on the Aerodynamic Performance of a Blended Wing Body Aircraft,” Aerodynamics and Thermofluids Group, Department of Mechanical Engineering, University of Sheffield, Sheffield, UK, 2006

[16] Schuhmacher, G., Murra, I., Wang, L., Laxander, A., O' Leary, O. J., and Herold, M., “Multidisciplinary Design Optimization of A Regional Aircraft Wing Box,” Fairchild Dornier GmbH, 82230 Wessling, Germany.

國際替代計量

翼胴合一飛行器之氣動力最佳化分析

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