船艦機庫幾何構型對直升機起降甲板風場結構之影響

THE INFLUENCE OF FRIGATE HANGAR GEOMETRIES TO THE FLOW STRUCTURES OF HELICOPTER FLIGHT DECK

直升機於船艦起降過程中可能遭遇氣流通過機庫時所產生之渦流結構影響，因此甲板上結構物對此區域風場的影響是重要的課題。本研究於迴流水槽針對水面艦的Simple Frigate Shape（SFS）模型，並參照現有船艦之機庫設計，以SFS模型為基礎衍伸Base、Corner、Incline、Chamfer四種機庫幾何構型，透過質點影像測速法量測直升機起降甲板的風場。量測結果包括量測平面之流線、流速、渦度與各方向紊流強度之分析，初步歸納其機庫結構所產生之跡流流場特徵，與其在不同迎風角下之流場差異性。再根據實驗結果的比較，得到各機庫幾何構型的流場結構差異，最後以此獲得之結論為基礎，給予直升機駕駛在不同條件下起降時對整體風場結構的判斷依據，或是瞭解其降落路徑可能遭遇之風向、紊流等，並提供未來船艦機庫外型設計上對直升機起降甲板風場進行優化設計之參考方向。

During the landing or taking off procedure on the flight deck of frigates, a helicopter might be influenced by the vortex structure caused by the wind passing through the hangar. To study the flow field in the region of flight deck, this research measured the flow field above the flight deck of Simple Frigate Shape (SFS) Models by using particle image velocimetry (PIV) in a circulating water tank. With observing the flow structure of four types of hangar (Base, Corner, Incline, and Chamfer) and analyzing the streamlines, flow speed, vorticity, and turbulence intensity, we can summarize the characteristics of flow structure influenced by the airwake of hangar. Therefore, with taking these conclusions as a basic knowledge, we offer pilots several guidelines to determine the flow structure under different conditions. Furthermore, it can also provide some concepts of flight deck flow field controlling and opti-mizing when designing the hangar in the future.