Noise prediction of a single-stream under-expanded jet in OpenFOAM

An jet of fully expanded Mach number Mj = 1.15 and Reynolds number Re = 1.25 million issues from a contoured converged axisymmetric sonic nozzle operated under-expanded. Large eddy simulations by OpenFOAM software model the unsteady jet. The shock cell train in the jet plume is captured by a modified Roe approximate Riemann solver. Shock-associated noise and mixing noise radiate to the acoustic far-field. The far-field noise directivity and spectral content are predicted by the Ffowcs Williams and Hawkings acoustic analogy implemented in libAcoustics in OpenFOAM. The aerodynamic and acoustic predictions compare favourably with published numerical predictions and experiments. This provides confidence in the use of OpenFOAM combined with libAcoustics for studying the flow and noise from high speed jets towards identifying more effective, economical, and sustainable methods of high speed jet noise abatement and control at source.