LES-RANS of installed ultra-high bypass-ratio coaxial jet aeroacoustics with a finite span wing-flap geometry and flight stream – part 2: Chevron nozzles

Chevrons are considered as an efficient passive way to reduce jet noise. Hybrid Large-Eddy Simulation (LES) and Reynolds-Averaged Navier-Stokes (RANS) is performed on an ultra-high bypass-ratio coaxial jet with chevrons on the outer nozzle. The Ffowcs Williams-Hawkings equation is used to predict farfield sound. Chevron effects are discussed with and without a finite span wing installation. The results are analyzed in terms of both near-field turbulence and far-field sound. Space-time correlations are also used to investigate turbulent spatio-temporal dynamics and sound sources. The results show that chevrons can reduce sound sources in the shear layer and the jet and wing/flap interactions, leading to noise reduction at both insolated and installed jets