Vortex-Shedding Induced Trailing-Edge Acoustics

The operational requirements for naval vessels have seen an increasing demand for quieter ships, and hence the management of the ship’s hydrodynamic signature requires improved predictions of flow induced noise and particularly propeller noise. Studies involving model-scale and full-scale ships are complicated and expensive, and in order to better understand the detailed physics and to develop better prediction models, simpler problems can be useful. In this work we consider the flow and flow induced noise from the trailing edge of a flat airfoil with a 45° asymmetrically beveled trailing edge and an elliptical leading edge. For the airfoil under consideration simultaneous flow and noise measurements from the University of Notre Dame are available for comparison with computational flow and acoustic models, making this a rather unique validation test case. Here we use Detached Eddy Simulation (DES), Large Eddy Simulation (LES) and Implicit LES (ILES) methods coupled to an acoustic model for the density (or pressure) perturbations similar to the standard Ffowcs-Williams & Hawkings or Lighthill-Curle's models. The comparison with the experimental data shows that both the flow and the acoustics are reasonably well predicted by all three models, but with the LES model resulting in somewhat more accurate flow and acoustic predictions.