Tones and upstream-traveling waves in ideally expanded round impinging jets

We study the role played by upstream-traveling guided waves on the generation of tones by a supersonic, ideally-expanded round jet impinging on a flat plate. We explore a finite-thickness stability model for the prediction of allowable frequency ranges for resonance based on the dynamics of such waves. We show that the frequency ranges predicted by the finite-thickness model are consistent with the vast majority of experimental and numerical data available in the literature, correcting discrepancies observed previously with vortex sheet models. This provides further evidence for the involvement of guided jet modes in the resonance mechanism.