ARTEM has successfully explored a large variety of concepts for passive and active noise reduction. Two liner concepts, namely the multi-focal and the slanted septum liner concept proved exceptionally good progress. An expected benefit of 0.7-0.9 EPNdB on aircraft level was estimated for a 2025 large long-range aircraft during the industrial assessment. All other concepts have also made significant progress in maturation reaching the expected TRLs of 3-4 depending on starting point.
Shielding modelling has been improved and finally successfully applied demonstrating the tremendous benefit with respect to noise reductions for ground observers if propulsion systems are placed on top of an aircraft structure – in particular here for blended wing body aircraft.
The complex flow and noise generation phenomena associated with conventional high-lift systems have been successfully modelled and noise reduction demonstrated by design variation like the very long chord slat (VLCS). The variety of modelling and prediction approaches from quick 2-D tools capable to handle many design variations during an optimization process and high-fidelity simulations including (Overset-)LES for in-depth analysis of noise generation mechanism will prove very useful for future aircraft system development work. Other means for noise reductions (serrations, finlets, porous inserts, etc) have been investigated numerically, experimentally and proved good results on component level, but lower impact during assessment on full aircraft scale.
The boundary layer ingestion concept (BLI), which is anticipated to reduce fuel consumption for “tube&wing” aircraft significantly, has been addressed in a comprehensive receiving great attention in the community. Tools from low-fidelity modelling to extensive numerical simulations on full aircraft scale using ONERA NOVA and NAUTILIUS platform have been applied. It was coherently demonstrated, that the inflow distortions associated with this concept are prone to increase the radiated propulsion noise – mainly fan noise – significantly. Great care is needed in the design of the inlet duct system to reduce inflow distortion as much as possible with extensive application of liners having the capability to further reduce or avoid any noise penalties.
For aircraft landing systems, a large campaign involved experimental and numerical work on detailed source analysis and promising reduction means as meshes, screens, fairing design, and porous inserts. While already demonstrating some potential noise reduction on model scale and during full aircraft assessment, the work performed in ARTEM constitutes a profound basis for on-going H2020 project INVENTOR work.
As a basis for distributed electric propulsion systems, a detailed study of mutual interaction effects of closely spaced rotors, and between rotor and wing structure has been performed in ARTEM. A purpose-build highly modular test setup consisting of a wing section and 3 propellers mountable in pusher and puller configuration was used to build-up a huge experimental data base and subsequent data processing and prediction tool development.
For the early design phase aircraft development, a robust multi-dimensional design optimization tool (MDO) was improved and subsequently applied to design two blended-wing body (BWB) aircraft configurations:
BOLT: a long-range BWB, REBEL: a short-range BWB aircraft with either classical UHBR engines (REBEL-C) or a distributed hybrid electrical propulsion system (REBEL-HEP).
The assessment for promising technologies on a CleanSky2-derived platforms for short-/medium range (SMR) and long-range (LR) aircraft has been performed by Airbus while a specific business jet platform was used by Dassault Aviation for the same task.
Based on noise predictions of the novel aircraft configurations, auralizations have been generated and used for comparative listening test concentrating also on psycho-acoustic aspects of annoyance of future aircraft noise.
