Aeroacoustic Computations for Turbulent Airfoil Flows
Aeroacoustic Computations for Turbulent Airfoil Flows
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DOI：
10.2514/1.40399
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发表时间：
2009-06
期刊：
影响因子：
2.5
通讯作者：
W. Shen;W. Zhu;J. Sørensen
中科院分区：
文献类型：
--
作者：
W. Shen;W. Zhu;J. Sørensen
本文将用于气动声学计算的流声分裂技术推广到三维湍流声传播的数值模拟。在流动部分，采用亚网格湍流模型（混合模型）进行大涡模拟。所获得的瞬时流的解决方案被用作输入的声学部分。在低马赫数下，流场和声场在尺度和传播速度上的差异很大，因此可以对这两部分采用不同的网格和时间步长。应用该模型计算了不同攻角下马赫数为0.2、雷诺数为1.6 × 10 - 5的NACA 0015翼型绕流。通过与实验数据的比较，验证了流场解的有效性.比较结果表明，在迎角到失速范围内，翼型升力特性的计算值和测量值之间有很好的一致性。对于声学的解决方案，预测的噪声频谱进行了验证定量对实验数据。对攻角在4 °和12 °之间流动的噪声模式的参数研究表明，攻角小于8 °时噪声级很小，从8 °到10 °时噪声级急剧增加，在12 °时达到最大值。
The flow-acoustic splitting technique for aeroacoustic computations is extended to simulate the propagation of acoustic waves generated by three-dimensional turbulent flows. In the flow part, a subgrid-scale turbulence model (the mixed model) is employed for large-eddy simulations. The obtained instantaneous flow solution is employed as input for the acoustic part. At low Mach numbers, the differences in scales and propagation speed between the flow and the acoustic field are quite large, and hence different meshes and time steps can be used for the two parts. The model is applied to compute flows past a NACA 0015 airfoil at a Mach number of 0.2 and a Reynolds number of 1.6 x 10 5 for different angles of attack. The flow solutions are validated by comparing lift and drag characteristics with experimental data. The comparisons show good agreements between the computed and measured airfoil lift characteristics for angles of attack up to stall. For the acoustic solutions, predicted noise spectra are validated quantitatively against experimental data. A parametrical study of the noise pattern for flows at angles of attack between 4 and 12 deg shows that the noise level is small for angles of attack below 8 deg, increases sharply from 8 to 10 deg, and reaches a maximum at 12 deg.