Exploration of Supersonic Jet Noise Mitigation for a Rectangular Jet Using Fluidic Injection

Supersonic jet noise is known to cause negative health effects on personnel and on aircraft structures. Experiment results have demonstrated that fluidic injection is effective at mitigating supersonic jet noise, but the mechanism for noise mitigation for rectangular jet is not well established. This paper presents the initial steps towards determining the mechanism. We explored the grid sensitivity of the acoustic prediction by comparing two baseline Large Eddy Simulation (LES) case. We find that it is critical to fully resolved relevant turbulence scale in order to get an accurate prediction for far-field acoustics. We further explored how the fluidic injection modifies the supersonic jet flow with a port injection configuration. It is found that the fluidic injection reduces the shock cell strength in potential core, most likely caused by the weakening of the shocks emanating from the nozzle lip and the increased level of turbulence in the initial shear layers near the nozzle outlet. Further iterations on the simulations for both baseline and fluidic injection will be conducted to further establish the mechanisms involved and allow more detailed comparison with the experiments.