源于边界层转捩区的单极子声辐射

Monopole radiation mechanisms of the laminar to turbulent transition region

基于 Ｌｉｇｈｔｈｉｌｌ方程和 Ｇｒｅｅｎ理论，本文对边界层转捩区声辐射机理进行了分析和讨论，并对转捩区内各声源的基本类型作了分类．分析结果表明；边界层转捩区的声辐射由转捩区内处于完全湍流状态的流体流动引起的向边界展外辐射的声场以及另两个附加声场组成；边界层转捩区声源的主要类型为单极子、偶极子和四极子声源；本文的分析为Ｌａｕｃｈｌｅ模型提供了理论依据，证明了利用Ｌａｕｃｈｌｅ模型估算转捩区远场声辐射基本准确可靠．

Based on the Lighthill equation and the Green's theory, the acoustic radiation mechanisms of the laminar to turbulent transition region are discussed and analyzed, and the fundamental types of sound sources at transition region are classified. It is shown that the acoustic field are generated by a fully developed turbulent flow with a modulation due to the intermittency and the two additional sound sources; the fundamental types of sound sources at transition region include monopole, dipole, and quadrupole source distributions; and Lauchle's phenomenological model for predicting the acoustic radiation of transition region is proved to be correct and reliable.