Adaptive, Overset-Mesh Methodology for the Aeroacoustic Prediction of High-Speed Impinging Jets Using Large-Eddy Simulation

Impinging supersonic jets can generate intense sound through a resonance phenomena, with tones approaching 15 dB beyond the already-loud baseline noise levels. The source of impinging jet noise, including that created by jet blast deflectors, is broadly the interaction between jet and deflecting plane, which can in certain cases close a resonant feedback loop. Accurate prediction of the noise is necessary for understanding the as-yet unknown detailed source mechanism(s), as well as enabling development of mitigation procedures. We seek to apply our validated LES prediction tool in Phase I to two well-documented cases of under-expanded jets impinging on a ground plane: one case resonates while the other does not. Our objective is to use our existing adjoint-based optimization methodology to highlight flow regions most sensitive to design changes or control strategies to reduce radiated noise. As shown in our previous, validated noise reduction efforts for turbulent jets, the adjoint provides a direct investigation into those areas of the flow, such as at the nozzle exit or ground plane, where a noise reduction strategy can be designed. GE Global Research has confirmed their strong interest in this R&D effort, and has agreed to provide critical guidance and review throughout Phase I.