本研究利用背向階梯流研究對於飛行載具上外型不連續處(例如火箭噴嘴)，探討在背向階梯上游加裝不同外形以及高度的渦流產生器對不同階梯高度的流場影響。本研究的自由流馬赫數為0.81；背向階梯模型高度(H)為3、5及7 mm；3種的渦流產生器為反向旋轉渦流產生器(Counter Rotating Vane Micro Vortex Generators-CRV MVGs)、同向旋轉渦流產生器(Co-Rotating Vane Micro Vortex Generators-CoV MVGs)以及三角斜坡渦流產生器(Triangular Ramp Micro Vortex Generators-TR MVGs)，渦流產生器高度 h 分別為1.4 mm和3.5 mm，h* (h⁄δ) = 0.2和0.5，h 為渦流產生器高度；δ 為邊界層厚度。本研究利用動態壓力傳感器進行量測，並且分析平均表面壓力以及擾動壓力；利用快速傅立葉及Welch方法分析頻譜；透過油流法判斷再循環區長度。
首先探討H的變化造成的表面壓力影響，背向階梯上游因黏滯-非黏滯作用(Inviscid-viscous interaction)造成流體膨脹的現象使表面壓力降低，此現象隨H的增加而上升，H的增加會使壓力回復的區域延長，代表再循環區長度會隨H的增加而增加，加裝MVGs所產生的渦流造成下游膨脹使表面壓力降低，其中CRV MVGs最為明顯，當增加 h 時會造成較強的下游膨脹，但此現象會隨H的增加而衰減。
背向階梯形成分離剪切流中的渦流撞擊到下游壁面為背向階梯流最主要的表面壓力擾動原因，表面壓力擾動量在H = 5 mm達到最大值。在上游因膨脹現象使表面壓力擾動壓量降低，此現象也在階梯下游發現，CRV MVGs為最能夠降低表面壓力擾動量，TR和CoV MVGs效果較差，增加 h 並不能提升降低表面壓力擾動量，當增加H，MVGs降低表面壓力擾動量的效果會降低。
從頻譜分布可以得知在下游最主要的現象為Step mode，即為渦流撞擊壁面所造成，當H增加時可以觀察到更多尺度渦流的訊號，加裝CRV14為最有效消除Step mode的能量。對於Flapping mode加裝MVGs並不能消除能量，反而會加劇其擾動，原因為Flapping mode的出現為剪切層與再循環區動量交換導致其震盪，MVGs的功用是利用渦流進行動量交換，因此造成Flapping mode的強度上升。
流場可視化油流法可以看出油料堆積線成二維分布，再循環區長度會和H呈線性增加，階梯處渦流堆積範圍隨 h 的增加而增加，加裝MVGs能夠使在循環區長度下降，最多能降低約30%。

This study determines the effect of micro vortex generators on a compressible backward-facing step flow. The free-stream Mach number for this study is 0.81 and the step height is 3, 5, and 7 mm (the ratio between the step height and the incoming boundary layer thickness = 0.43, 0.71 and 1.0). Three types of vortex generators are used: Counter Rotating Vane Micro Vortex Generators (CRV MVGs), Co-Rotating Vane Micro Vortex Generators (CoV MVGs) and Triangular Ramp Micro Vortex Generators (TR MVGs). The height of vortex generators is 1.4 mm and 3.5 mm (the ratio between the height of vortex generators and the incoming boundary layer thickness = 0.2 and 0.5). The experimental data shows that an increase in the height of the step results in stronger downstream flow expansion. The presence of micro vortex generators induces vortical structure and downstream expansion. There is a decrease in the value of minimum surface pressure, particularly for the CRV MVGs. The height of vortex generators is another important factor. An increase in the height of vortex generators results in stronger downstream expansion, but this effect diminishes as H increases. Peak pressure fluctuations are determined near the reattachment location. The presence of vortex generators results in a reduction in the value of peak pressure fluctuations, particularly for the CRV MVGs. A reduction in the peak pressure fluctuations in more significant when there is an increase in the height of the step, but this is not true as the height of vortex generators increases. The spectral analysis determines that downstream flow is dominated by the Step mode, particularly when there is an increase in the height of the step. The presence of vortex generators enhances the momentum exchange which leads to an increase in the intensity of the Flapping mode. The Step mode is alleviated using CRV14 vortex generators. Oil surface flow visualization shows a two-dimensional flow. The length of recirculation zone increases linearly with the height of the step and there is a reduction when the vortex generators are installed.

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