Noise shielding of a deflected flap for comparing numerical predictions with flyover experiments

Comparing acoustic simulations against experimental data is an essential step in order to prove the correctness of numerical tools. This can be done with wind tunnel experiments where the environmental conditions can be adjusted very accurately. Ultimately, the tools must be capable of predicting real-word scenarios like aircraft flyovers. However, obtaining precise data from flyover experiments is challenging and often important input data is missing. The current paper shows, that by extracting the shielding effect of a small detail, a deflecting flap of an aircraft with rear-mounted engines, it is possible to reproduce flyover measurements with a boundary element method, even when only little engine information is known. The boundary element method can only take a constant mean flow into account, but by additionally evaluating results of a volume-resolved discontinuous Galerkin method more insights into the expected effects of a realistic mean flow is given.