Stability of Non-Ideally Expanded Jet Impinging on a Flat Plate

Recently, advances were achieved in the understanding and the modelling of the screech mechanism in free supersonic jets, as well as on tonal noise from subsonic and ideally expanded supersonic impinging jets. For tonal noise in supersonic non-ideally expanded impinging jets, however, clear modelling is still missing in the literature. In this study, we propose to derive a simple 1D model relying on Linearized Euler Equations and adequate boundary conditions in order to model the aeroacoustic feedback loop that arises, in some configurations, between the last stand-off shock and the flat plate. The model is validated first against an analytical model in an idealized case where a linear decrease of the flow mean velocity is assumed between the stand-off shock and the flat plate. The model is then used in various other cases and uses different sets of parameters to analyse its performance.