本研究針對具15o後掠角之NACA 0012剖面的有限長度懸臂機翼，探討雷諾數及攻角的變化，對後掠翼表面流場、氣動力性能及尾流區之流場結構的影響。在低雷諾數區域，透過煙線流場可視化的觀察，翼表面的流場行為有五種特徵模態產生，分別為貼附表面流、不穩定波尾流、渦旋尾流、翼前緣分離及鈍體尾流模態。在高雷諾數區域，藉由表面油膜流法觀察，翼表面的流場行為有六種特徵模態發生，分別為層流分離、分離泡、翼前緣泡、分離泡延展、紊流分離及鈍體尾流模態。故在弦長雷諾數對攻角的圖面上，可劃分出十一種表面流場之特徵模態，這些表面流場的動態衍化與時間平均的流形，均以拓樸分析而得到特徵模型。利用六力平衡儀量測後掠翼之氣動力性能，搭配流場觀察的結果，發現氣動力性能與表面流場的特徵有密切的關係，並且在翼表面的流場特徵為分離泡延展模態時發生失速。根據熱線風速儀輸出的時序圖及所對應的頻譜圖，尾流區有四種不同的渦旋流逸之特徵，分別為層流、次臨界、過渡及超臨界模態。渦旋流逸的特徵與表面流場之行為有密切的相關。將渦旋流逸的頻率作無因次化分析，而獲得渦旋流逸的頻率、史卓數及洛斯柯數與雷諾數及攻角之間的關係。並以統計分析的理論，針對尾流區不同的渦旋流逸之特徵，探討概率密度函數、相關係數、渦旋與紊流的時間尺度與長度尺度。最後，針對不同的翼表面之流場特徵，應用PIV的技術，取得表面流場結構之全域速度場，得到量化的流場結構，使得拓樸結果更清晰的顯現。同時，環繞在機翼周圍的渦度場與紊流場特性也都予以量化。

Effects of the chord Reynolds number and root angle-of-attack on the surface flow, the vortex shedding, and the aerodynamic performance of a finite back-swept wing are experimentally studied. The cross-sectional profile of the wing is NACA 0012 and the back swept angle is 15 degrees. The aspect ratio of the finite wing is 5. The surface flow field is visualized by using the techniques of the smoke-wire and the surface oil-flow. Five characteristic flow modes are found in the low Reynolds number regime according to the smoke-streak flow patterns and six are categorized at high Reynolds numbers by observing the patterns of the surface oil-flow. Flow topologies of the surface flow modes in various characteristic flow regimes and the time-dependent wake evolution processes are analyzed by the separatrices, alley ways, and critical points. A six component balance is employed to measure the aerodynamic performance. A hot-wire anemometer is used to detect the frequency variation of the unsteady structure in the wake. It is found that the aerodynamic performance of the wing and the Strouhal characteristics of the vortical evolution in the wake are closely related to the characteristic modes of the surface flow. In addition, the vortex shedding in the wake presents variations in turbulence characteristics, which can also be attributed to the changes in characteristic modes of the surface flow. The statistical properties of turbulence, e.g., the power spectrum density function, probability density function, correlation coefficient, time and length scales of turbulence are extracted from the raw data obtained from the hot-wire anemometer measurements. Additionally, the velocity field around the wing section is quantified by employing the particle image velocimeter (PIV). The velocity vector field, streamline patterns, vorticity distributions, and turbulence kinetic energies of various flow modes are presented and discussed.

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