民航機遭遇強烈大氣亂流瞬間起伏運動之飛行動力機制

Mechanisms of Sudden Plunging Motion for Transport Aircraft in Severe Atmospheric Turbulence Performances

藍川滔(C. Edward Lan)；臧瑞傳(Ray C. Chang)

大氣亂流 ； 飛行數據紀錄器 ； 飛行環境 ； 機制 ； 模糊邏輯模型化 ； atmospheric turbulence ； flight data recorder (FDR) ； flight environment ； mechanism ； fuzzy-logic modeling (FLM)

航空安全及管理季刊

3卷2期（2016 / 04 / 01）

134 - 154

繁體中文

民航機在飛行中承受大氣亂流會造成氣動力與飛行動力特徵迅速地改變，這種特徵改變不僅會威脅到飛航安全，也可能造成結構損壞及減少疲勞壽限。因為突然的起伏運動經常會造成旅客及機組人員受傷，確定導致起伏運動的飛行動力機制是非常重要的。本論文之主要目的是使用飛行數據記錄器（Flight Data Recorder, FDR）中取得的飛行數據來展示兩架相似類型的雙發動機噴射民航機在穿音速飛行遭遇到強烈大氣亂流突然的起伏運動時的飛行動力機制之比較分析。兩架民航機在飛行軌跡重現下，起伏運動的飛行動力機制能夠明顯地呈現。本研究之成果將可提供降低危害的概念，並可增進對於民航機在強烈大氣亂流中的氣動力效應之瞭解。

The transport aircraft in flight is subjected to atmospheric turbulence resulting in rapidly varying aerodynamic and flight dynamic characteristics. These varying characteristics not only pose threats to flight safety, but also may cause structural damages and reduce fatigue life. Since the sudden plunging motion frequently causes injuries to passengers and crew members, it is important to determine the flight dynamic mechanisms that induce the motions. This paper presents the comparative analyses of flight environment and source of wind for two similar twin-jet transports before and during turbulence encounter. The angle of attack for one of these two transports reaches 7.1 deg. in cruise at transonic speed before the plunging motion. Numerical calculation of a typical supercritical airfoil shows strong shock wave and possible flow separation at 6.5 deg. in angle of attack. Based on shock-induced flow separation and the resulting estimated lift curve slope, high-speed stall should be the reason for plunging motion in cruise at transonic speeds. Therefore, the source of significant angles of attack will be the main task of investigation in the present paper. The results indicate that if the increase in angle of attack at a transonic speed coincides with that in pitch angle, the increase in angle of attack would be larger and should be produced by the pitching moment due to inertial coupling. The resulting high-speed stall would produce larger abrupt drop in altitude. Otherwise, the increase in angle of attack is most likely due to the upflow in the random turbulent air and would not produce large abrupt drop in altitude.

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