- 學位論文
封閉式機翼應用在高空長滯空太陽能無人機之氣動力分析
Investigation of Aerodynamic Characteristics of Closed Wing Applied on High-Altitude, Long-Endurance Solar UAV
摘要
封閉型機翼之無人飛機具重量輕、高強度、低誘導阻力、穩定性及控制性佳、以及具抵抗強側風、強逆風、亂流等優點，因此成為極具發展潛力的項目。本研究旨在針對高空、長滯空無人飛行器之封閉式機翼外形進行設計，並針對其氣動力性能做分析，並期待在飛行器的外型設計能夠使整體達到最佳化。本文以Ansys Fluent，並使用具SST K-ω紊流模組進行數值模擬，探討封閉型機翼在改變不同垂直距離、水平距離及下翼為後掠式之氣動力特性，並且分析在何種配置下能有較佳的效果。 分析三維封閉式機翼在自由流風速12m/s，發現流體流經封閉型機翼所產生之翼尖渦流明顯小於直翼式機翼(SINGLE WING)。在矩形式封閉型機翼 0≦D/c≦6 及 0.5≦H/c≦2 之結果顯示，當固定D/c時，CL開始時會隨著H/c增加而提升，當H/c增加至1.5時整體CL增加的幅度已趨近飽和。當固定H/c時，CL會隨著D/c增加而提升。在所探討案例中，當D/c=0、1.5、3、6時，最佳整體平均CL¬分別為SINGLE WING的88.4、93%、94.8、101.4%。在後掠式封閉型機翼的部分，整體CL皆隨著D的增加而減少，D/c=0.5時之整體平均CL皆為最佳。在升力與重量比方面，在相同展弦比下，整體BOXWING之L/Waf與L/W皆大於SINGLE WING。在所探討案例中，最大平均L/Waf及L/W 增益值分別為 265%及102%，在相同負載的情況下，因BOXWING所需升力較小，使阻力也較小，使整體動力輸出較低，進而增加續航力；在相同升力的情況下，因BOXWING重量較低，因此可多酬載許多設備，如：電池、太陽能板及其他相關設備。
並列摘要
Closed wing has the advantage including low weight, high stiffness, low induced drag and good stability, and has great potential for development of HALE Solar UAV. This study focuses on reducing the structure weight as well as enhancing stability of maneuverability and environmental tolerance without comprising aerodynamic characteristics. The effects of configuration parameters and installation arrangement of the closed wing designed under different operational conditions have been discussed in detail for the aerodynamic performance. The 3D numerical simulation integrated SST k-ω turbulence module is performed to investigate the aerodynamic characteristics of closed wing in different vertical and horizontal distances of upper and lower wing, and the swept angle of lower wing. The wing tip vortex influence to closed wing is less than SINGLE WING. For rectangular closed wings with 0≦D/c≦6 and 0.5≦H/c≦2, the CL grows as H/c increases initially and saturate as H/c=1.5 when D/c is fixed. Meanwhile, the CL grows as D/c increases when H/c is fixed. Comparing with the single wing, the average CL are 88.4%, 93%, 94.8% and 101.4% of SINGLE WING as D/c=0、1.5、3、6. For swept closed wings with 0≦D/c≦2, the CL decreases as D/c increases and D/c=0.5 has the best average CL. In the same aspect ratio, both L/Waf and L/W for BOXWING are all better than SINGLE WING. Comparing with the single wing, the maximum enhancement of L/Waf and L/W for BOXINNGWING are about 265% and 102%.