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Static and Dynamic Aerodynamic Comparisons for Stealthy/Conventional Aerial Vehicles in Water Tunnel
|關鍵字:||X-45A Stealth Shape;X-45A匿蹤機型;Static/Dynamic Aerocharacteristics Comparison;Longitudinal Stability;Hysteresis Phenomena;水洞試驗;靜動態氣動力特性比較;縱向穩定性;遲滯現象||出版社:||機械工程學系所||引用:||References 1. Rangke, M. and Yongnian, Y., “Advances of Studies for the Buffet Problem of Aircraft,” Chinese Journal of Applied Mechanics, Vol. 18, No. z1, 2001, pp.142~150. 2. Stacey, J. C. and Bjarke, L. J., “Flow- Visualization Study of the X-29A Aircraft at High Angles of Attack Using a 1/48-Scale Model,” NASA Technical 104268, 1994. 3. Cunningham, A. M., Jr. and Bushlow, T., “Steady and Unsteady Force Testing of Fighter Aircraft Models in a Water Tunnel,” AIAA, 1990-2815, Washington, DC, 1990, pp. 222~237. 4. Cummings, R. M., Morton, S. A., and Siegel, S. G., “Numerical Prediction and Wind Tunnel Experiment for a Pitching Unmanned Combat Air Vehicle,” Aerospace Science and Technology, Vol. 12, No. 5, July 2008, pp. 355~364. 5. Bragg, M. B. and Soltani, M. R., “Measured Forces and Moments on a Delta Wing During Pitch-Up,” Journal of Aircraft, Vol. 27, No. 3, March 1990, pp. 262~267. 6. Okamoto, S., “Visualization of Impingement of Broken-Down Vortex on Tail,” Journal of Wind Engineering and Industrial Aerodynamics, Vol. 91, No. 1, January 2003, pp. 65~74. 7. Merret, J. M. and Bragg, M. B., “X-38 Aerodynamics during Rapid Pitch Up”, 21st Applied Aerodynamics Conference, AIAA 2003-3526, Hilton Head, South CA, May, 2003. 8. Elkhoury, M. and Rockwell, D., “Visualized Vortices on Unmanned Combat Air Vehicle Planform: Effect of Reynolds Number,” Journal of Aircraft, Vol. 41, No. 5, May 2004, pp. 1244~1247. 9. Elkhoury, M. and Yavuz, M., “Near-Surface Topology of an Unmanned Combat Air Vehicle Planform: Reynolds Number Dependence,” Journal of Aircraft, Vol. 42, No. 5, September-October 2005, pp. 1318~1330. 10. Patel, M, P., Ng, T. T., and Vasudevan, S., “Plasma Actuators for Hingeless Aerodynamic Control of an Unmanned Air Vehicle,” Journal of Aircraft, Vol. 44, No. 4, August 2007, pp. 1264~1274. 11. Erickson, G. E., “Water-Tunnel Studies of Leading-Edge Vortices,” Journal of Aircraft, Vol. 19, No. 6, 1982, pp. 442~448. 12. Olsen, P. E. and Nelson, R. C., “Vortex Interaction Over Double-Delta Wing,” AIAA Paper 89-2191-CP, 1989. 13. http://en.wikipedia.org/wiki/Boeing_X-45 14. Chang, L. M., Lee, H. J., Huang, C. M., Chuang, S. H., Wang, S. W., and Chien, K. T., “Static and Dynamic Aerodynamics Testing of Strake-Wing Aerial Vehicle in Water Tunnel,” Transactions of the Japan Society for Aeronautical and Space Sciences, Vol. 53, No.180, Aug. 2010, pp. 91~98. 15. Lamar, J. E. and Frink, N. T., “Experimental and Analytical Study of the Longitudinal Aerodynamic Characteristics of Analytically and Empirically Designed Strake-Wing Configurations at Subcritical Speeds,” NASA TP-1803, 1981. 16. Chang, L. M., Lee, H. J. Chuang, S. H., Chiu, K. J., Chien, K. T., and Hsu, L. H., “Experimental Investigation on Low-Speed Aerodynamic Performance of Stealth Crafts at High Angles of Attack in a Water Tunnel (in Chinese),” Journal of Aeronautics, Astronautics and Aviation, Vol. 39, No. 2, Oct. 2007, pp. 99~106. 17. Wang, S. W., Chuang, S. H., Wu, C. H., Hsu, L. H., and Huang, C. M., “Study on Static and Dynamic Aerodynamic Characteristics of Double Delta Wing at High Angles of Attack,” Journal of Aeronautics, Astronautics and Aviation, Vol. 40, No. 3, Sep. 2008, pp. 151~162. 18. Dole, C. E. and Lewis, J. E., Flight Theory and Aerodynamics: A Practical Guide for Operational Safety, Reston, Virginia, Wiley, 2000. 19. Huenecke, K., Modern Combat Aircraft Design, Annapolis, Naval Institute Press, 1987.||摘要:||
本文主要是利用水洞試驗研究具有匿蹤外形之Boeing X-45A模型與傳統非匿蹤外形之NASN TP-1803比較其渦流流場與氣動力特性。實驗結果顯示：於靜態俯仰過程中且低攻角範圍（α < 20°）不僅X-45A正向力係數Cn的增加大於TP-1803正向力係數的增加，而且縱向穩定性上X-45A也優於TP-1803。然而α > 20° 之後TP-1803的Cn值反而會大於X-45A的Cn值，而且X-45A之縱向不穩定性會較早發生。α < 20° 範圍中，X-45A在靜態上仰過程之正向力係數是快速的增加，下俯過程之正向力係數是緩慢的減少。然而TP-1803上仰/下俯過程Cn值表現出相近的線性增減。動態俯仰過程結果顯示TP-1803會比X-45A產生更大的正向力遲滯。此外由於動態上仰過程X-45A之最大俯仰力矩Cm大於TP-1803，因此X-45A是會比TP-1803產生更大的縱向不穩定性。另外X-45A在各種頻率（K）之俯仰過程中α-Cn曲線均呈現順時針的遲滯環特徵。而且當K值增加模型所產生之遲滯行為會更為明顯，於低攻角範圍中上仰過程的縱向不穩定性以及下俯過程縱向穩定性均會更為顯著。
This paper highlights the water tunnel experiments of both the Boeing X-45A stealth drone model and the traditional NASA TP-1803 model without semblance of stealth, and compares their wing vortex structures and aerocharacteristics for several parameters. The experiments show that the normal force coefficient (Cn) of the X-45A increases much more than that of the TP-1803 for α < 20° in the static processes, and the X-45A has better longitudinal stability than the TP-1803. For α > 20°, the Cn of the TP-1803 is larger than that of the X-45A. Further, the longitudinal instability of the X-45A occurs earlier than the TP-1803. Further, For α < 20° the Cn of the X-45A increases rapidly in the pitch-up process, but decreases slowly for the pitch-down process. The Cn of the TP-1803 occurring in the pitch up/down processes are approximately linear at α < 20°. The dynamic normal fore experiment shows more tremendous hysteresis for the TP-1803 than the X-45A. In addition, in the pitch-up process, the maximum Cm in the X-45A is larger than that of the TP-1803, hence the longitudinal stability of the X-45A appears more instable at maximum Cm, as compared to the TP-1803. Besides, the X-45A for different reduced frequency (K) processes, the curves of α-Cn all exhibit clockwise patterns, with similar hysteresis loop characteristics. Moreover, as the reduced frequency increases hysteresis behaviors becomes more obvious. The longitudinal instability appears clearer in the pitch-up processes and the longitudinal stability appears for low AOA in the pitch-down processes.
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