实验研究钝后缘（blunt trai领 edge）流场在声音产生中

The unsteady lift generated by the flow of turbulence over the trai领 edge of an airfoil can be an effective source of dipole sound. The objective of the present research was to experimentally measure the velocity field behind an asymmetric 45 degree beveled trai领 edge in order to develop an understanding of the flow mechanisms responsible for the generation of trai领 edge noise. Particle Image Velocimetry (PIV) data were acquired in the near wake region of the trai领 edge at a chord Reynolds number of 1.9x106. The time averaged velocity statistics are indicative of a wake flow containing semi-periodic vortex shedding. These large scale shedding motions are commonly responsible for the tonal noise produced by the trai领 edge. A phase average decomposition of the velocity field with respect to this shedding process was utilized to separate the small scale turbulent motions responsible for broadband sound production. This analysis has shown that the characteristics of the small scale turbulence are dependent on the phase of the vortex shedding process. 德国LaVision PIV/PLIF粒子成像测速场仪 Imager SX PIV相机 用于粒子成像测速(PIV)的荧光示踪粒子