Uncertainty quantification of the far-field noise from a rod-airfoil configuration

A Large-Eddy Simulation (LES) solver together with a Ffowcs-Williams and Hawking (FW-H) solver are coupled with a non-intrusive stochastic collocation method to propagate the geometric uncertainty observed in a rod-airfoil experiment. The LES are performed for several displacements of the rod with respect to its nominal position in the cross-wise direction. The positions are chosen to match the Clenshaw-Curtis (CC) points. The acoustic fields are obtained using an FW-H analogy on aerodynamic results sampled over the time on a porous surface embedded in the mesh. An uncertainty quantification is then performed on the mean and fluctuating root-mean-squared (rms) velocity at several transverse profiles, on the mean wall-pressure coefficient Cp on the airfoil and on both the acoustic spectra and the directivity. The uncertainty of the rod position only partially recovers the discrepancies seen in the experimental data. An uncertainty in the position of the rod of ±0.004 m leads to an uncertainty of 0.5-1 dB in the Overall Sound Pressure Levels (OASPL).