Dynamics of closely spaced supersonic jets

Abstract

A twin-jet configuration is composed of two jets placed in closed proximity to each other. Previous works on such configurations have been mostly experimental in nature. The aim of this work is to computationally analyze a twin-jet configuration and identify the impact of plume interactions on various aspects, such as shear-layer characteristics, coherent structures, mixing, and the near acoustic field. A large-eddy simulation (LES)-based approach is employed to study a Mach 1.23 circular twin-jet configuration with an internozzle spacing of two jet diameters. In agreement with the established literature, results indicate a dominant m 1 helical mode on both the jet plumes. In the internozzle region, mean velocity profiles indicate the formation of a secondary flow, which extends a significant influence on the shear layers in its proximity. However, this impact is confined to small azimuthal angles and, as a result, many of the potential core properties are almost similar to those of a single jet at identical flow conditions. Along the plane containing the jet centers, analysis of the near-field pressure fluctuations reveals that the twin jet exhibits suppressed levels relative to a single jet. This is ascribed to twin-jet plume bending along with reduced outer shear-layer spreading rate.