Linear instability in the wake of an elliptic wing
Linear instability in the wake of an elliptic wing
复制标题
椭圆翼后的线性不稳定性
DOI：
10.1007/s00162-016-0400-2
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发表时间：
2017
影响因子：
3.4
通讯作者：
V. Theofilis
中科院分区：
文献类型：
--
作者：
Wei He;Juan Ángel Tendero Ventanas;P. Paredes;V. Theofilis
在使用适当缩放的 Eppler E387 翼型构建的椭圆形横截面的低展弦比三维机翼之后，进行了线性全局不稳定性分析。翼型上方及其尾流的流场已通过完整三维直接数值模拟计算，弦雷诺数为 $$Re_{c}=1750$$Rec=1750，两个攻角为 $$\mathrm{{AoA}}=0^\circ $$AoA=0∘ 和 $$5^\circ $$5∘。点涡流方法已被用来预测该流的无粘性对应物。控制叠加在粘性三维尾流上的线性小幅度扰动的空间 BiGlobal 特征值问题已在多个轴向位置得到解决，结果用于初始化线性 PSE-3D 分析，除了所有流量对轴向空间方向的弱依赖性外，无需对尾涡系统的形式进行任何简化假设。识别出两类线性不稳定扰动，即较强放大的对称模式和较弱放大的反对称扰动，两者均在连接尾涡的涡旋片处达到峰值。记录了两类模态的振幅函数，并将它们的特性与对称平面附近和涡核附近的尾流中的局部线性稳定性分析所提供的特性进行了比较。虽然所采用的所有线性不稳定性分析方法都提供了定性一致的预测，但只有 PSE-3D 不受有关基础基流的假设的影响，因此应用于获取此类配置中的放大率和振幅函数的定量信息。
Linear global instability analysis has been performed in the wake of a low aspect ratio three-dimensional wing of elliptic cross section, constructed with appropriately scaled Eppler E387 airfoils. The flow field over the airfoil and in its wake has been computed by full three-dimensional direct numerical simulation at a chord Reynolds number of $$Re_{c}=1750$$Rec=1750 and two angles of attack, $$\mathrm{{AoA}}=0^\circ $$AoA=0∘ and $$5^\circ $$5∘. Point-vortex methods have been employed to predict the inviscid counterpart of this flow. The spatial BiGlobal eigenvalue problem governing linear small-amplitude perturbations superposed upon the viscous three-dimensional wake has been solved at several axial locations, and results were used to initialize linear PSE-3D analyses without any simplifying assumptions regarding the form of the trailing vortex system, other than weak dependence of all flow quantities on the axial spatial direction. Two classes of linearly unstable perturbations were identified, namely stronger-amplified symmetric modes and weaker-amplified antisymmetric disturbances, both peaking at the vortex sheet which connects the trailing vortices. The amplitude functions of both classes of modes were documented, and their characteristics were compared with those delivered by local linear stability analysis in the wake near the symmetry plane and in the vicinity of the vortex core. While all linear instability analysis approaches employed have delivered qualitatively consistent predictions, only PSE-3D is free from assumptions regarding the underlying base flow and should thus be employed to obtain quantitative information on amplification rates and amplitude functions in this class of configurations.
模拟前缘凹坑对横流不稳定性的三维影响
DOI：
10.1016/j.piutam.2015.03.041
发表时间：
2015
期刊：
Procedia IUTAM
影响因子：
--
作者：
Ashworth R
通讯作者：
Ashworth R