Turbulent Characteristics of Compressible Jet from a Chevron Nozzle: A Numerical Study

Abstract

The aim of the present study is to computationally investigate the turbulent characteristics of a high-speed jet at exit Mach 0.8 from a chevron nozzle. A Chevron nozzle with a chevron crest angle of 45° is used and flow characteristics are investigated and compared with base nozzles at two different axial locations from nozzle exit; x/D = 0.5 and x/D = 5. Contours of turbulent intensity suggest that the chevron helps in the reduction of turbulence downstream of the potential core, which results in lowering jet noise. Turbulence is reduced by the enhanced mixing between the two fluids which is mainly due to the formation of a pair of vortices rotating in opposite directions which is evident in the vorticity contours. The development of a counter-rotating pair of vortices results in the formation of lobed structures in the flow field close to the chevron nozzle exit. Similar results can be observed for turbulent intensity at the lip line as well as the centerline. The baseline nozzle causes more turbulence than the chevron nozzle thus increasing the sound level.