Conjunction of Aeroelasticity and Aeroacoustics in Transonic Cavity Flow

Paper in proceeding, 2022

The effects of elastic cavity walls on noise generation at transonic speed are investigated for the generic M219 cavity. The flow is simulated with Spalart-Allmaras (SA) improved delayed detached-eddy simulation (IDDES) in combination with a wall function. The structural analysis software, which is strongly coupled with the flow solver, uses a modal formulation. The first 50 structural normal mode shapes are included in the simulation, spanning frequencies 468–2280 Hz. Results are compared with those from a reference simulation with rigid cavity walls. Spectral analysis of pressure fluctuations at microphones above the cavity evinces a distinct tone at 816 Hz, which is absent in the reference simulation. Moreover, the power of the 4th Rossiter mode at 852 Hz is depleted, implying a significant energy transfer from the fluid to the structure. Spectral proper orthogonal decomposition (SPOD) is employed for analyses of cavity wall pressure fluctuations and wall displacements. The SPOD mode energy spectra show results consistent with the spectra at the microphones, regarding the tone at 816 Hz and the depletion of the energy at the 4th Rossiter mode. In addition, the SPOD mode energy spectra show energy spikes at additional frequencies, which coincide with structural eigenfrequencies