Jet Installation Noise Modelling Informed by GPU LES

Abstract

Jet installation beneath a wing significantly enhances jet noise at low frequencies, and its physical mechanism must be comprehended to develop efficient noise reduction solutions. A numerical investigation on the jet-installation noise is performed using Wall Modelled Large Eddy Simulation (WMLES) performed using the high-resolution CABARET method accelerated on Graphics Processing Units. To simulate jet installation, a flat plate is put outside of the jet's plume, causing a rise in noise levels due to the scattering of near-field hydrodynamic waves at the trailing edge of the plate. The configuration adopted in this work replicates a series of experiments performed at the University of Bristol, against which the numerical results are validated. The numerical simulation is performed for Mach numbers of 0.5 and 0.9, and the influence of the selected noise reduction technique, i.e., the usage of chevron nozzles in comparison with the baseline round nozzle, on the jet-installation is studied by modelling SMC006 chevron nozzle. The properties of jet-hydrodynamic pressure variations and their effect on nozzle type and Mach number are investigated. Far-field noise spectra from the isolated and installed jet cases, obtained through the Ffowcs-Williams Hawkings method, are compared at different polar angles. In addition, a hybrid semi-analytical hydrodynamic-edge scattering prediction model is implemented following the model of Lyu and Dowling [1] to analyse jet-installation noise, using inputs obtained directly from the LES calculation. The implemented model is found to capture the correct physics at peak jet installation frequencies and can be used as a robust prediction tool for jet-installation noise optimisation in the future.