LES–RANS study of serrated nozzle jet aeroacoustics for an installed ultra-high-bypass-ratio aeroengine

Jet noise is amplified at low frequencies when the jet is installed under a wing. Serrations are designed at the nozzle exit to mitigate installation noise generation. In this paper, hybrid large-eddy simulation (LES) and Reynolds-averaged Navier–Stokes (RANS) is performed to investigate the serration effects on installed jet flows and acoustics in an industrially relevant configuration: an ultra-high-bypass-ratio aeroengine mounted under a three-dimensional wing. The results show that the serrations are able to weaken jet and wing interactions, and consequently reduce far-field installation noise. The noise reduction mechanisms have been sought through the quadrupole sources in the jet plume and evanescent pressure wave scattering at the wing trailing edge.