Physics-based Modelling for Aircraft Noise and Emission Predictions

Licentiate thesis, 2022

Starting from semi-empirical noise source models for the aircraft and 4D trajectory computations, this work focuses on the environmental assessment of scenario studies regarding technology evaluation and procedural planning. Extensive work was performed on improving and validating the existing tools. The physics based dynamic modelling for straight inflight was extended to account for a third space dimension and the inclusion of non-zero wind. Real flight data were used for model verification. Ground noise measurements were used to validate the physics-based prediction of source noise for varying operating conditions and to adapt the model to a state-of-the-art aircraft and engine. In this thesis, a summary of the developed physics-based methods and their validation are presented and the selected case studies are described.
An important part of the presented research focused on sustainability aspects and the evaluation of interdependencies between noise, NOx and CO2 emissions. New propulsion system designs were generated for a state-of-the-art ultra-high bypass ratio turbofan engine by allowing variation in the OPR (Overall Pressure Ratio), FPR (Fan Pressure Ratio) and BPR (Bypass Ratio). By varying these parameters, the engine was optimized for minimum installed specific fuel consumption. Allowing minimum fuel burn variation around this optimal point, different engine designs and operational characteristics were established and trades between LTO (Landing and Take-off) NOx emissions and cumulative noise were examined.
Another aspect focusing on the sustainability of air transport concerns the operational level, where the aim is to establish improved procedures and trajectories through the use of the existing technology. Several noise abatement procedures already exist and are implemented to reduce pollution around airports. Focusing on approach procedures, these standard operations were evaluated for noise and emissions. More advanced procedures were designed and assessed for their environmental impact and optimization was carried out to establish the optimal procedure for specific cases. It was demonstrated that quantifying these trade-offs and adapting the design to specific conditions is essential when new flight procedures are designed.