臺灣博碩士論文加值系統

長滯空無人機具有臨時基地台、偵測地方空氣指標等用途，比起建造固定式設施，使用無人機能夠更方便的架設與收回。數值模擬常用於無人機的初步設計，比起實驗其成本相對較低且較不受人為因素及環境的影響，本研究目的在對長滯空無人機進行結構分析，探討無人機在不同狀態下的結構應力現象，並了解其振動特性，以期能建構出完整之飛行包絡圖，作為無人機操作之規範，避免無人機因不當操作，造成機體損壞。
研究中所探討的無人機實體模型翼展5.6公尺、全長2.1公尺、全機總重約8.5公斤，巡航時大約以每秒10到15公尺的速度飛行。首先進行整架無人機的結構分析，探討每個部位的應力分佈情形，接下來利用模態分析找出與機翼有關的自然振動頻率，並藉由探討翼樑參數來了解不同剖面對於機翼的影響。在討論動態行為前，先藉由流場分析了解飛行速度與飛行攻角之間的關聯性，然後利用流固耦合分析來探討流場與結構間的相互影響，過程中討論了不同形式的單向流固耦合，並將結果與雙向流固耦合進行比較，接下來利用流場分析及流固耦合分析之結果得出無人機之飛行包絡線。
研究結果顯示無人機的應力主要由翼樑來承受，有關機翼之前4個自然振動模態分別為搖晃型、拍翼型、轉翼型及扭翼型。根據翼樑剖面之形狀參數比較結果，當翼樑使用矩形剖面時可以比使用圓形剖面時的機翼變形量減少30%，但重量會增加11%。在穩態流場中，攻角對於升力的影響隨著風速的增加越來越明顯，結構變形的成長速度在飛行速度提高的同時也隨之增加。不同方式的單向耦合在穩定後結果差異不大，但若將此結果與雙向耦合相比，兩者數值相差約10%。飛行包絡線探討了7.07m/s到20m/s的飛行速度區間的結構負載情形，結果顯示飛行安全區落在正負載因子2.6到負負載因子1.0的之間。

Long endurance unmanned aircraft can use for temporary base stations or air indicators. Compared with stationary equipment, unmanned aircraft is more convenient to erect and retract. Numerical simulation is used for the preliminary design of the unmanned aerial vehicle (UAV) because of its low cost and less affected by humans and the environment. The purpose of this research is to analyze the structure of long-endurance unmanned aircraft. Explore the stress of UAV under different conditions, and understand its vibration characteristics. It is hoped to construct a flight envelope diagram, used as a standard for UAV operation. To avoid damage to the UAV because of the improper operation.
In this paper, unmanned aircraft has a wingspan of 5.6 meters, a total length of 2.1 meters, and the weight of the UAV is 8.5 kg. It flights at a speed of 10 to 15 m/s while cruising. First, analyze the structure of the UAV to explore the stress distribution of each part. Then use modal analysis to find out the natural vibration frequency related to the wing. Change the spar parameters to understand the effect of different profiles on the wing. Before discussing the dynamic behavior, the flow field analysis is used to understand the relationship between the flight speed and the flight angle of attack (AOA). Then the fluid-structure interaction (FSI) analysis is used to discuss the interaction between the flow field and the structure. During the process, different forms of one-way FSI were discussed, and the results were compared with the two-way FSI. Finally, the results of flow field analysis and FSI analysis are used to obtain the flight envelope.
The results show that the spar is the main component to withstand stress. The first four natural vibration modes of the wing are shaking, flapping, rotating, and twisting. According to the comparison of the shape parameters of the spar section, when the spar uses a rectangular section, the deformation of the wing can be reduced by 30%, but the weight will increase by about 11%. In the steady-state flow field, the influence of the angle of attack on lift becomes more obvious with the increase of wind speed, and so is the growth rate of structural deformation. There is no significant difference in the results of different forms of one-way FSI, but compared with two-way FSI, the difference between them is about 10%. The flight envelope explored the structural loading in the flight speed range from 7.07 to 20m/s, and the results showed that the flight safety zone was between a positive load factor of 2.6 and a negative load factor of 1.0.

摘要 ................................................ i
Abstract ........................................... ii
誌謝 ............................................... iv
目錄 ................................................ v
表目錄 ............................................ vii
圖目錄 ........................................... viii
符號說明 ........................................... xi
第一章 緒論 ........................................ 1
1.1 研究動機與目的 .................................. 1
1.2 文獻回顧 ....................................... 1
1.3 文章架構 ....................................... 2
第二章 物理系統與統御方程式 ......................... 3
2.1 無人機問題 ..................................... 3
2.2 結構分析方程式 ................................. 4
2.2.1 應力、應變與位移關係式 ....................... 4
2.2.2 板殼理論 .................................... 5
2.2.3 振動模式 .................................... 6
2.3 氣動力分析 .................................... 7
2.4 飛行包絡線 .................................... 9
第三章 數值方法與驗證 ............................. 11
3.1 數值方法 ..................................... 11
3.1.1 結構網格與分析設定 .......................... 11
3.1.2 流場網格與分析設定 .......................... 12
3.1.3 流固耦合分析 ................................ 12
3.2 程式驗證 ..................................... 13
3.2.1 網格收斂性測試 .............................. 13
3.2.2 數值方法結果驗證 ............................ 14
第四章 結果與討論 ................................. 15
4.1 全機結構受力與振動模態 ......................... 15
4.2 翼樑參數探討 .................................. 16
4.3 機翼流固耦合動態分析 ............................18
4.4 飛行包絡線 .................................... 19
第五章 結論 ....................................... 21
參考文獻 .......................................... 54
Extended Abstract ................................ 56

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