翼型尾缘噪声源空间分布与辐射特性关系

详细研究了翼型湍流边界层尾缘宽频噪声源空间分布与辐射特性的关系.采用基于雷诺平均流场的翼型尾缘宽频预测方法研究了NACA0012翼型湍流边界层尾缘宽频噪声在4种不同工况下的噪声源空间分布与辐射特性.首先计算了NACA0012翼型湍流边界层尾缘噪声源在不同频率下的空间分布.计算结果发现:边界层中湍流是翼型湍流边界层尾缘噪声声源.随着频率的增加，噪声源强度和噪声源空间尺寸都是先增加后减小，噪声源位置不断靠近翼型尾缘.同时也计算了边界层内不同位置处的噪声源对远场噪声的辐射特性，结果表明:边界层内层区域，其噪声频谱能量集中在高频；边界层外部区域，其噪声能量集中在中低频；攻角增大或者来流速度减小，噪声能量向低频转移. 

Relationship between noise sources spatial distribution and radiation characteristic of airfoil trailing edge

The relationship between the airfoil turbulent boundary layer trailing edge noise spatial distribution and radiation characteristic was studied in detail. A Reynolds averaged Navier-Stokes (RANS) based airfoil trailing edge noise prediction method was employed to investigate the NACA0012 airfoil turbulent boundary layer trailing edge noise source spatial distribution and radiation characteristic at four different operating conditions. The spatial distribution of NACA0012 airfoil turbulent boundary layer trailing edge noise source at different frequencies was calculated firstly. It indicated that the turbulence within boundary layer was responsible for the airfoil turbulent boundary layer noise. Meanwhile the source region approached to the trailing edge of airfoil with increase of the noise frequency; it was also shown that the spatial dimension of source and the strength of the source increased first and then decreased with the increase of frequency; meanwhile, the noise radiation characteristic from different source regions in boundary layer was computed secondly. It demonstrated that the noise from source region in boundary inner layer was concentrated on high frequency and the boundary outer layer was responsible for the low frequency of noise. The noise energy moved to low frequency with increase of angle of attack or decrease of incoming flow velocity.