平板湍流边界层的声辐射

Direct Acoustic Radiation from Turbulent Boundary Layer

基于平板湍流边界层的壁压起伏波数—频率谱 ,给出了一种湍流边界层声辐射的估算方法 ,并对光滑平板湍流边界层和平板表面粗糙度引起的湍流边界层声辐射进行了分析。结果表明 :湍流边界层声辐射是一种四极子声辐射 ,且其辐射声能集中于平板表面粗糙度引起的湍流边界层声辐射 ;光滑平板湍流边界层的声辐射也不可忽略。

Based on the wavenumber frequency spectrum of pressure fluctuations on a flat plate turbulent boundary layer, the field averaged power spectral density of acoustic radiation from the turbulent flow is predicted, and the acoustic radiation from both smooth and rough wall boundary layers at low flow Mach numbers are analyzed. It is shown that the sources of sound production are quadruple in nature, and the sound energy radiated from the roughness enhanced Reynolds stresses are predominant in all of the direct acoustic radiation, but the acoustic radiation from turbulent layer on smooth wall cannot be ignored also.