Aeroacoustic instability analysis of a Helmholtz resonator using a High-Order DG Solver based on URANS equations

The paper presents an analysis of the aeroacoustic instabilities in a slit-type Helmholtz resonator subjected to a low Mach number grazing flow. This configuration can be susceptible to non-linear feedback phenomena due to the interaction between the hydrodynamic and acoustic field in the orifice proximity. The aeroacoustic flow field is simulated by solving the 2D unsteady Reynolds averaged Navier-Stokes (URANS) equations using a high-order discontinuous Galerkin (DG) solver. The response of the Helmholtz resonator to an incident acoustic field is analyzed using a two-port characterization technique. The onset of the aeroacoustic instabilities is investigated by applying an acoustic energy criterion based on the scattering matrix formulation. The numerical results are compared to experimental data obtained in a measurement campaign carried out at the KU Leuven test facility. The comparison between the numerical and experimental data demonstrates a very good agreement, highlighting the potential of the applied numerical approach for the aeroacoustic instabilities investigation.