Scale-Resolving Simulation of Aeroacoustic Sound from Coanda Flaps

This manuscript summarizes the work performed by the authors (project A8) as part of the Collaborative Research Centre CRC 880 Fundamentals of High Lift for Future Civil Aircraft. Our work aimed to further enhance the understanding of the source mechanisms of solid and porous materials inside turbulent flows by the use of scale-resolving simulations. On the basis of a novel Large Eddy Simulations approach, called Overset-LES, the source mechanism and sound reduction of porous materials were investigated. The governing equations are based on the compressible Navier-Stokes equations in perturbation form. The presence of porous material was modelled by a volume-averaged approach. This volume-averaged model, including nonlinear terms, serves to clarify the sound generation while fully accounting for the nonlinear interaction between fluid and acoustics. The developed hybrid zonal simulation tool with volumetric inflow forcing was applied to a NACA0012 airfoil’s trailing-edge, with or without a porous insert, at representative Mach and Reynolds number of 0.1118 and \(1.0\times 10^6\), respectively. Three dimensional simulations of the NACA0012 trailing edge (with a solid and porous inset) showed good agreement with aerodynamic and aeroacoustic validation experiments. Applying porous material to the trailing-edge’s noise confirms the results reported in literature and underlines the validity of the porous model as well as it illustrates possible further applications. The same computational approach was applied to the situation of a Coanda flap, showing that such computations are feasible with practical computational resources.