The effects of hybrid porous-serrated trailing edge on flow structure and sound source of NACA65(12)-10 at moderate Reynolds number (R_ec = 5 × 10⁵) have been investigated by Delayed Detached Eddy Simulation (DDES). Compared with conventional serrated trailing edge, the pressure fluctuation in the vicinity of hybrid porous-serrated trailing edge is further decreased significantly. The typical necklace vortex structures stretching across adjacent serrations are suppressed by the porous additive. It is found that porous media changes the shear stress distribution along the serration edge and inside the serration gap, which consequently eliminates the generation of necklace vortex. Therefore, the deformation of vortex tube caused by velocity vector is weakened. The underlying mechanisms associated to the sound source modification are analyzed based on vortex sound theory. The magnitude of Lamb vector and the angle between vorticity and velocity vectors are synchronously reduced by the porous additive, which implies that the present hybrid porous-serrated trailing edge has important influence on the further attenuation of far-field aerodynamic noise.

中文翻译：

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混合多孔锯齿形后缘对流动结构和声源的修正

中等锯齿雷诺数（R _ec = 5×10 ⁵）时，多孔锯齿状混合后缘对NACA65（12）-10流动结构和声源的影响）已通过延迟分离涡流仿真（DDES）进行了研究。与传统的锯齿状后缘相比，混合多孔锯齿状后缘附近的压力波动进一步减小。多孔添加剂抑制了横跨相邻锯齿延伸的典型项链涡流结构。发现多孔介质改变了沿锯齿边缘和锯齿间隙内部的切应力分布，因此消除了项链涡流的产生。因此，减弱了由速度矢量引起的涡流管的变形。基于涡旋声理论分析了与声源修改相关的潜在机制。