Aeroacoustic properties of a supersonic diamond-shaped jet

Abstract

The potential for using a novel diamond-shaped nozzle, which may allow superior mixing and noise characteristics of supersonic jets without significant thrust losses, is explored. Flow visualization and pressure measurements indicate the presence of distinct structures in the shear layers, not normally observed in shear layers of ideally expanded axisymmetric and rectangular jets. The characteristics of these features suggest that they are a manifestation of significant streamwise vorticity in the shear layers. Despite the distinct nature of the flowfield structure of the diamond jet, the far-field noise characteristics are quite similar to those of the corresponding axisymmetric jet, except moderate mixing-noise reduction in the aft quadrant. Furthermore, the global shear-layer growth rates are also very similar to those of the axisymmetric and two-dimensional counterparts. These observations lead one to believe that the presence of streamwise vorticity may not play a significant role on the overall mixing and noise generation of a supersonic jet.