Dynamic flow distortion investigation in an S-duct using DDES and SPIV data
Dynamic flow distortion investigation in an S-duct using DDES and SPIV data
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DOI：
10.2514/6.2016-3562
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发表时间：
2016-06
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通讯作者：
Daniel Gil-Prieto;D. MacManus;P. Zachos;G. Tanguy;F. Wilson;N. Chiereghin
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文献类型：
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作者：
Daniel Gil-Prieto;D. MacManus;P. Zachos;G. Tanguy;F. Wilson;N. Chiereghin
涡旋式航空发动机进气道内产生的动态流动畸变会影响发动机的性能和可操作性。有必要更好地了解在s形进气道出口处促进流动畸变的主要流动机制。本文基于延迟分离涡模拟，对s型管道流场的主要相干结构进行了详细分析。通过在气动界面平面上的高分辨率、同步立体粒子图像测速实验，证明了该数值方法捕捉高度非定常流场特征的能力。确定了引起管道出口主要扰动的流场机制。在分离区周围以St=0.53的频率交替产生顺时针和逆时针方向的涡流，促进了管道出口的旋流切换。横向涡也以St=1.06的频率从分离区脱落，沿分离的中线剪切层向下游对流。这导致了主损失区域的垂直调制和气动界面平面上高低速流之间速度梯度的波动。
The dynamic flow distortion generated within convoluted aero-engine intakes can affect the performance and operability of the engine. There is a need for a better understanding of the main flow mechanisms which promote flow distortion at the exit of S-shaped intakes. This paper presents a detailed analysis of the main coherent structures in an S-duct flow field based on a Delayed Detached Eddy Simulation. The capability of this numerical approach to capture the characteristics of the highly unsteady flow field is demonstrated against high resolution, synchronous Stereoscopic Particle Image Velocimetry measurements at the Aerodynamic Interface Plane. The flow field mechanisms responsible for the main perturbations at the duct outlet are identified. Clockwise and counter-clockwise stream-wise vortices are alternately generated around the separation region at a frequency of St=0.53, which promote the swirl switching at the duct outlet. Spanwise vortices are also shed from the separation region at a frequency of St=1.06, and convect downstream along the separated centreline shear layer. This results in a vertical modulation of the main loss region and a fluctuation of the velocity gradient between the high and low velocity flow at the Aerodynamic Interface Plane.