Noise simulations on an airfoil with trailing-edge serrations: Validation of a hybrid RANS/LES approach

A hybrid Reynolds Averaged Navier Stokes (RANS)/Large Eddy Simulation (LES) approach to predict airfoils with Trailing-Edge Serrations (TES) both, aerodynamically and aeroacoustically, is validated using experimental results on trailing–-edge noise from a NACA 633–018 airfoil for a chord–-based Reynolds Number (Re) of 3, 9 × 104. It was experimentally analyzed in the TU Delft wind tunnel, where aerodynamic and acoustic data was collected in the anechoic test section. A highly automated process chain was developed to assess the aerodynamic performance of serrated blade sections, develop efficient wind tunnel tests, and support design questions during the development process. The process comprises the parametrization and meshing of the blade sections, performs the simulations, and conducts the post–processing of the results. A standard Unsteady Reynolds Averaged Navier Stokes (URANS) approach was utilized for purely aerodynamic investigations, whereas an embeddedLES approach was used to predict the aeroacoustics of the airfoil. Therein, synthetic turbulence being injected in the mid–chord region of the airfoil is propagated to the trailing–edge within a wall–modeled LES subdomain. The far–field noise is evaluated employing the Ffowcs-Williams and Hawkings (FW-H) acoustic analogy by placing the evaluation surface on the airfoil’s solid boundary. The aerodynamic characteristics, boundary layer parameters, far–field trailing–edge noise from the baseline airfoil with a straight trailing–edge and trailing–edge serrations are investigated. Detailed aerodynamic analyzes focusing on the effect of different parameters on the aerodynamics as well as a thorough aeroacoustic evaluation will be shown in the full thesis.Aerospace Engineerin