Promising low-noise aircraft architectures have been identified over the last few years at DLR. A set of DLR aircraft concepts was selected for further assessment in the context of sustainable and energy-efficient aviation and was established at the TU Braunschweig in 2019, the Cluster of Excellence for Sustainable and Energy-Efficient Aviation (SE2A). Specific Top-Level aircraft requirements were defined by the cluster and the selected DLR aircraft designs were improved with focus on aircraft noise, emissions, and contrail generation. The presented paper specifically addresses the reduction of aviation noise with focus on noise shielding and modifications to the flight performance. This article presents the state of the art of the simulation process at DLR and demonstrates that the novel aircraft concepts can reduce the noise impact by up to 50% in terms of sound exposure level isocontour area while reducing the fuel burn by 6%, respective to a conventional aircraft for the same mission. The study shows that a tube-wing architecture with a top-mounted, forward-swept wing and low fan pressure ratio propulsors installed above the fuselage at the wing junction can yield significant noise shielding at improved low-speed performance and reduce critical fuel burn and emissions.

Particle Image Velocimetry (PIV) is an important technique to investigate complex flow fields but limited to the tracking fidelity of the flow tracers and the uncertainties in the evaluation process. To examine these issues this work implements a physic-based motion simulation for small spherical particles, serving as flow tracers in PIV, with existing tools for image generation. Particular focus set on the behavior in vortical structures and the occurrence of "particle voids" due to centrifugal forces. The results show that a realistic particle distribution ideally can be achieved when applying a statistical distribution of the particle size. Furthermore, they suggest a significant error in the velocity prediction if the region of interest has no sufficient particle seeding.