Large Eddy Simulation of Co-Axial Jets and Analysis of Sound Sources

Large eddy simulation (LES) of co-axial jets at acoustic Mach numbers of 0.7 and 0.63 for the main and by-pass flows was carried out. Characteristics of the internal and external shear layers, spectral features of velocity fluctuations, and interactions between the vortical structures were investigated. It was shown that there was a clear difference between the convection velocities close to the jet-exit in two shear layers. In the downstream, convection velocity in the internal shear layer was suppressed by the external shear layer. The study with acoustic perturbation equation(APE)indicated that the main vortex-sound source occurred in the internal shear layer, with the dominant components were at low frequencies. With the increase of radius, the position of the spectral peak of the vortex source fluctuations moves close to the jet-exit. © 2020, Science Press. All right reserved.