微風暴曾經造成許多次飛機失事事件，本文之目的在於利用穩定及非穩定狀況下之環狀渦旋流來模擬微風暴的流場。起始條件爲一突發之噴射氣流，在不同時刻之兩個環狀渦旋流，其相互作用及流場示意圖將予以充份討論。此計算所得之流場除可做爲飛行訓練之用外，且可增加吾人對於微風暴之了解。 Microbursts formed near airports during thunderstorm activities have been responsible for severa1 major airliner crashes. This weather phenomenon features a sudden and very intense down flow that can cause even the most sophisticated aricraft to quickly lose altitude: Proper air1ine transport pilot training in flight simulators is an effective way of achieving greater safety to aircraft against microbursts. Both steady and unsteady multiple-vortex ring models are developed to simulate microbursts. The models use an impulsive free jet as an input to provide the central axial velocity of the vortex rings and their mirror images. Wind velocity fields are plotted to display the ca1culation results. For unsteady flow, trajectory plots are a1so made to demonstrate how the locations of the two vortex rings vary in two vortex rings arc discussed. The predicted penetration of the smaller vortexring through the larger one, when they share a common central axis, is shown in one of the unsteady cases.
中國航空太空學會學刊=Transactions of the Aeronautical and Astronautical Society of the Republic of China 26(4)，頁265-275