Numerical Studies on the Sound Radiation by the Shocklets in the Two-dimensional Mixing Layer

摘要

The flow and sound generation of 2D mixing layers at Mc=0.75 arerninvestigated with four different disturbance patterns. Various vortices evolution,rnincluding the single vortex, two vortices pairing and three vortices merging, occurrnbecause of different dominant Kelvin-Helmholtz instability mode. In each case,rnshocklets would appear and radiate sound effectively since the induction of thernvortices. The hydrodynamics and acoustics characteristics of the mixing layers arerninvestigated. For the hydrodynamics, the evolutions of disturbance energy andrnvarious thickness of mixing layer are calculated; for the acoustics, we analyzed thernmovement of shocklets and their influences to the sound radiation. The sources ofrndifferent modes, the directivities of the sound radiation and the attenuation law arernstudied quantitatively.