Numerical prediction of passenger cabin noise due to jet noise by an ultra–high–bypass ratio engine

Abstract

Within the framework of the Collaborative Research Center 880, future civil transportation aircraft are investigated. One major aim is a drastic reduction of the noise emission to the ground and an appropriate noise immission into the passenger cabin. The latter forms the focus of this contribution with the aim to ensure an equal or lower noise level in the cabin for new aircraft configurations. Numerical methods are applied to establish a multidisciplinary modeling chain resulting in a prediction of cabin noise due to jet noise by two different engine configurations. An ultra–high–bypass ratio engine is compared to a conventional engine on the basis of a preliminary aircraft design used for both configurations. On the basis of flow calculations in cruise flight as operation point, 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. These loads are applied to a finite element model considering the structure and the fluid of the aircraft cabin. The acoustic model resolving the structure-borne and airborne sound waves is derived from the design data. The results show a lower sound pressure level induced by the ultra–high–bypass ratio engine in the entire frequency range on the outer skin. Within the cabin, the modern engine is still much quieter, though this fact is not generally valid for the entire frequency range as transmission effects of the double wall occur.