Wave-Resolving Numerical Prediction of Passenger Cabin Noise Under Realistic Loading

Abstract

An important design objective of future aircraft configurations is a low noise transmission into the passenger cabin. Mechanical models and its numerical solution allow analyses of the noise transmission from the source to the passenger ear. Within this contribution, numerical methods are applied within a multidisciplinary simulation chain resulting in a prediction of cabin noise due to fluid noise sources. Noise by the jet and the turbulent boundary layer are expected as two major noise sources which are considered in this contribution. Jet noise is computed for two different engine configurations which are compared to the turbulent boundary layer noise in the passenger cabin. The contribution of the engine fan is not accounted for within this study. In the multidisciplinary simulation chain, the hybrid Computational Aeroacoustics solver PIANO combined with the Fast Random Particle Mesh method is applied to compute the pressure fluctuations due to jet noise on the outer skin of the fuselage. For the turbulent boundary layer, analytic calculations of auto-spectra and wavenumber-spectra are transferred to pressure fluctuations on the outer skin as well. The loads are applied to a wave-resolving finite element model of the research aircraft by the Collaborative Research Center 880. The model is derived from the available design data and solved with the in-house research code elPaSo. First, the results show a much lower sound pressure level in the cabin induced by a novel ultra–high–bypass ratio engine in comparison with a conventional engine. Second, it is shown that the turbulent boundary layer becomes the dominating noise source for cabin noise in future aircraft driven by a third generation engine.