Sound quality assessment of a medium-range aircraft with enhanced fan-noise shielding design

Gil Felix Greco,Tobias P Ring,Lothar Bertsch,Sabine C Langer

doi:10.1007/s13272-021-00515-9

Gil Felix Greco, Tobias P Ring + Show 2 more

Open Access

https://doi.org/10.1007/s13272-021-00515-9

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Abstract

The investigation of technologies that can improve the sustainability of the air transport system requires not only the development of alternative fuel concepts and novel vehicle technologies but also the definition of appropriate assessment strategies. Regarding noise, the assessment should reflect the situation of communities living near airports, i.e., not only addressing sound levels but also accounting for the annoyance caused by aircraft noise. For this purpose, conventional A-weighted sound pressure level metrics provide initial but limited information as the level- and frequency-dependency of the human hearing is accounted for in a simplified manner. Ideally, subjective evaluations are required to adequately quantify the perceived short-term annoyance associated with aircraft noise. However, listening tests are time-consuming and not suitable to be applied during the conceptual aircraft design stage, where a large solution space needs to be explored. Aiming at bridging this gap, this work presents a methodology for the sound quality assessment of computational aircraft noise predictions, which is hereby conducted in terms of objective psychoacoustic metrics. The proposed methodology is applied to a novel medium-range vehicle with fan noise shielding architecture during take-off and landing procedures. The relevance of individual sound sources, i.e., airframe and engine noise contributions, and their dependencies on the aircraft architecture and flight procedures are assessed in terms of loudness, sharpness, and tonality. Moreover, the methodology is steered towards community noise assessment, where the impacts on short-term annoyance brought by the novel aircraft design are analysed. The assessment is based on the modified psychoacoustic annoyance, a metric that provides a quantitative description of human annoyance as a combination of different hearing sensations. The present work is understood as an essential step towards low-annoyance aircraft design.

Highlights

To compensate the adverse environmental impacts brought by the civil aviation, the European vision set by Flightpath 2050 [1] aims at ambitious goals: a reduction of 75 % on CO2 emissions per passenger kilometer and a 65 % cut of Regarding noise, a comprehensive assessment should consider the situation of the exposed communities living at the vicinities of airports by addressing sound levels and accounting for the annoyance caused by aircraft noise
Our analysis shows that the V-2 vehicle, even with the noise shielding promoted by the engine position above the aircraft fuselage, promoted no significant tonality reductions when compared to the reference vehicle during approach
The environmental noise impact of a novel medium-range aircraft design with a high-wing layout and enhanced sound shielding properties due to the positioning of the engines above the fuselage is assessed in terms of objective psychoacoustic metrics

Summary

Introduction

To compensate the adverse environmental impacts brought by the civil aviation, the European vision set by Flightpath 2050 [1] aims at ambitious goals: a reduction of 75 % on CO2 emissions per passenger kilometer and a 65 % cut of Regarding noise, a comprehensive assessment should consider the situation of the exposed communities living at the vicinities of airports by addressing sound levels and accounting for the annoyance caused by aircraft noise. Level (SEL) metric per flight which is translated into an energy equivalent sound pressure level to describe the long-term impact of the air-traffic on communities. The complex temporal and spectral structure associated with the noise perceived during each fly-over event is not directly taken into account, the quantitative assessment does not include enough information to quantify human annoyance. Another typically applied metric is the Effective Perceived Noise Level (EPNL), which was developed in the 1960’s as a predictor of human annoyance to aircraft noise [3]. The EPNL tone correction procedure is often discussed in the literature regarding its capabilities to quantify subjective responses to aircraft noise that contains multiple complex tones [5, 6]

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