Today's aircraft noise calculation programs either use simple sound source descriptions with few input parameters or highly sophisticated models with input parameters, which are difficult to obtain. To fill the gap between these two approaches, an aircraft noise emission model based on regression of measured noise with aircraft flight parameters is presented. To find a reasonable compromise between the degree of detail and number of required flight parameters, an extensive data exploration was conducted. The most relevant parameters were incorporated in two multiple linear regression models, one for airframe and one for engine noise sources. An iterative method allowed fitting both regression models to aircraft flyover measurements. In total, aircraft noise emission models for 19 aircraft types were established, which underlines the general applicability of the modeling approach to turbofan-powered aircraft. Example comparisons between measurements and model predictions for two aircraft types revealed that the model accurately reproduces directivity and spectra for different flight configurations. In addition, it is suitable for the assessment and optimization of noise abatement procedures.

The ircr ft noise simul tion model sonAIR h s been designed to precisely predict single flights with the scope of investig ting nd optimising noise b tement procedures. With its current implement tion it is lso possible to do noise m pping for entire irports. The simul tion process is b sed on time-step ppro ch in which single flights re represented in high tempor l resolution. Sever l sound emission models re v il ble, from det iled models for turbof n powered ircr ft, which describe irfr me nd engine noise sep r tely with t hree dimension l sound directivity p ttern, to simplified models for wide v riety of propeller driven ircr ft nd helicopters. A det iled sound prop g tion model is used, which for ex mple p ys p rticul r ttention to ir ttenu tion through str tified tmosphere. The whole simul tion ch in is formul ted for one-third oct ve b nds within frequency r nge of 25 Hz to 5kHz. The full implement tion of the progr m in g eogr phic inform tion system (GIS) llows for user-friendly c lcul tion process. In this contribution n overviewofthe model nd the c lcul tion process is given, nd first results of model verific tions s well s pplic tion ex mples re presented.

sonAIR is a recently developed aircraft noise simulation model designed for single flight simulation while still being applicable for calculation of entire airport scenarios. This paper presents a rigorous validation exercise, wherein roughly 20’000 single flights were simulated using the 22 currently available sonAIR emission models of turbofan aircraft and compared against noise measurements. The measurements were recorded with the noise monitoring terminals at Zurich and Geneva airport, Switzerland, and with additional microphones installed by the author’s institution. Data from 22 measurement positions were analyzed, covering all departure and approach routes at distances from 1.8 to 53 kilometers from the airports. sonAIR was found to be accurate for departures and approaches under different operating conditions and aircraft configuration. The mean overall differences between simulation and measurements were well below ±1 dB in terms of noise event levels, with standard deviations of ±1.7 dB respectively ±2.4 dB, depending on the model type. A few aircraft types that displayed larger deviations are discussed individually. A sensitivity analysis on the input data found the quality and level of detail of the land cover data to be critical for the simulation accuracy. Changes in other input data such as atmospheric profiles and buildings had non-significant impacts.

Abstract:The strategic European paper "Flightpath 2050" claims dramatic reductions of noise for aviation transport scenarios in 2050: ". . . The perceived noise emission of flying aircraft is reduced by 65%. These are relative to the capabilities of typical new aircraft in 2000. . . ". There is a consensus among experts that these far reaching objectives cannot be accomplished by application of noise reduction technologies at the level of aircraft components only. Comparably drastic claims simultaneously expressed in Flightpath 2050 for carbon dioxide and NOX reduction underline the need for step changes in aircraft technologies and aircraft configurations. New aircraft concepts with entirely different propulsion concepts will emerge, including unconventional power supplies from renewable energy sources, ranging from electric over hybrid to synthetic fuels. Given this foreseen revolution in aircraft technology the question arises, how the noise impact of these new aircraft may be assessed. Within the present contribution, a multi-level, multi-fidelity approach is proposed which enables aircraft noise assessment. It is composed by coupling noise prediction methods at three different levels of detail. On the first level, high fidelity methods for predicting the aeroacoustic behavior of aircraft components (and installations) are required since in the early stages of the development of innovative noise reduction technology test data is not available. The results are transferred to the second level, where radiation patterns of entire conventional and future aircraft concepts are assembled and noise emissions for single aircraft are computed. In the third level, large scale scenarios with many aircraft are considered to accurately predict the noise exposure for receivers on the ground. It is shown that reasonable predictions of the ground noise exposure level may be obtained. Furthermore, even though simplifications and omissions are introduced, it is shown that the method is capable of transferring all relevant physical aspects through the levels.

No abstract