Numerical Investigation of Installed Jet Noise Sensitivity to Lift and Wing/Engine Positioning

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.As the turbofan engines of modern transport aircraft have increasingly larger bypass ratios, by necessity to avoid longer undercarriage, the engine must be installed closer to the wing. This then has the potential of interaction between the jet flow and a deployed flap. This interaction can be an important noise source when the high-lift systems are deployed, as at approach and take-off. Investigating the parameters that have a strong influence on the installation noise penalty can help in identifying noise reduction measures. In this paper Wall-Modelled Large Eddy Simulations (WMLES), combined with the FfowcsWilliams and Hawkings (FW-H) sound extrapolation method, are performed to reproduce three experimental cases, with the aim of isolating the different contributions of flap angle and trailing-edge/jet-axis distance h. The first case (DOAK), consisting of a single jet installed near a horizontal flat plate, confirms the fundamental mechanisms of jet-surface interaction and jet-surface reflection in the absence of lift. The second case (DLR-F16), with a coaxial jet installed under a high-lift wing, reveals the trailing-edge/jet-axis distance h as the dominant parameter, with a possible influence of the flap angle at low frequencies. The third case (SYMPHONY) is used to study the interaction of a coaxial jet with a full aircraft geometry using Fourier decomposition of the pressure near-field to analyse the effects on sound sources and radiation