Abstract Hybrid methods for trailing edge noise prediction are applied to a NACA 6512-63 airfoil at zero angle of attack embedded in the actual narrow stream of the Siegen open-jet anechoic wind-tunnel. Incompressible large-eddy simulations (LES) of the airfoil trailing-edge flow yield the noise sources, and different analytical acoustic analogies then predict the acoustic far-field pressure. The chord-based Reynolds number of 1.9 × 105 triggers long laminar flow regions along the airfoil, leading to instability waves with an associated broadband noise radiation. To avoid this laminar-instability noise, the airfoil boundary layer is experimentally tripped on both sides. The actual serration tripping is included in the numerical grid as well as a simplified stair-step trip. Aerodynamic and acoustic results of the performed LES are compared with measurements and compressible direct numerical simulation (DNS) results. No noticeable influence of the trip geometry is found whereas the numerical schemes play a more important role. LES predictions with boundary layer trip compare well with experimental measurements and DNS cases. If the boundary-layer trip is not sufficiently thick in the numerical model, or not present at all, the far-field acoustic pressure is overpredicted and resembles more closely the sound radiation from the untripped airfoil with laminar instability noise.

中文翻译：

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边界层跳闸机翼后缘宽带噪声预测

摘要 将后缘噪声预测的混合方法应用于嵌入 Siegen 开放式喷气消声风洞实际窄流中零攻角的 NACA 6512-63 翼型。机翼后缘流的不可压缩大涡模拟 (LES) 产生噪声源，然后不同的分析声学类比预测声学远场压力。基于弦的雷诺数 1.9 × 105 触发沿翼型的长层流区域，导致不稳定波和相关的宽带噪声辐射。为了避免这种层流不稳定性噪声，翼型边界层在两侧进行了实验性跳闸。实际的锯齿跳闸包括在数字网格中，以及简化的阶梯跳闸。将执行的 LES 的空气动力学和声学结果与测量结果和可压缩直接数值模拟 (DNS) 结果进行比较。没有发现行程几何的显着影响，而数值方案起着更​​重要的作用。LES 对边界层行程的预测与实验测量和 DNS 案例相比很好。如果数值模型中的边界层行程不够厚，或者根本不存在，则远场声压会被高估，并且更接近于具有层流不稳定噪声的未行程机翼的声辐射。LES 对边界层行程的预测与实验测量和 DNS 案例相比很好。如果数值模型中的边界层行程不够厚，或者根本不存在，则远场声压会被高估，并且更接近于具有层流不稳定噪声的未行程机翼的声辐射。LES 对边界层行程的预测与实验测量和 DNS 案例相比很好。如果数值模型中的边界层行程不够厚，或者根本不存在，则远场声压会被高估，并且更接近于具有层流不稳定噪声的未行程机翼的声辐射。