Shock-induced noise in supersonic jets

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Supersonic jets with complex shock-cell structures produce broadband and smallband noise (screech tones) of high intensity which contributes to structural fatigue and to strong environmental noise pollution. While the screech frequencies are theoretically predictable, their amplitudes cannot, until now, be computed precisely. It is the aim of this project to predict such noise levels reliably and to contribute to a better understanding of the fundamental physics of shock-induced noise generation and propagation. Two different highly accurate compressible Navier-Stokes solvers, available at TU Munich (TUM) and École Centrale de Lyon (ECL) will be used to perforin direct numerical and large-eddy simulations of supersonic perfectly expanded and overexpanded round jets. While the group at ECL will concentrate on LES, the group at TUM will use DNS for flow and noise prediction. One common low Reynolds number flow-case will be defined which allows to compare noise predictions by LES and DNS. Detailed supersonic jet data are the input for noise propagation studies based on the linearized Euler equations. The goal of the project during the next 3-year phase will be related to the control of shockinduced noise by shape modifications of the nozzle lip.