Aircraft pass-by noise on ground modelled with the SAFT-program

摘要

SAFT (Simulation of atmosphere and Air traffic For a quieter environmenT) is the name of a simulation tool for aircraft noise propagation that has been developed at CIT, Chalmers and KTH since the end of 2016. It is funded through CSA - Centre for Sustainable Aviation at KTH. Already in its current state SAFT enables aircraft pass-by noise estimations of several kinds. The set of computational approaches stretches from the most complex "full-simulation" ones, involving directivity, time-and frequency dependent individual (jet, fan, flaps,...) noise sources as well as sound propagation through a refractive atmosphere, down to the more old-fashioned "integrated" computational methods such as given in ECAC doc.29. Special attention has been paid to making the tool user-friendly and fast to run. Even in the case with a refractive atmosphere model SAFT runs at rather short CPU-times thanks to a new concept of a Transmission Loss interpolation matrix. The typical result from SAFT-runs is either a noise-contour map (LA_(max), SEL(A) or other metric) or the noise level time history in selected ground points (for simulation computations only). Other features involves possibilities to plot AdB-contours from "any possible" model-, parameter- or aircraft procedure variation. E.g. comparison of results such as from ECAC doc.29 vs "full-simulation", aircraft A vs aircraft B, weather condition X vs weather Y, different absorption models, different engine, airframe or procedure modifications etc. In a planned effort noise-source data in SAFT is to be extended with measured aircraft pass-by noise, time-correlated with FDR or/and trajectory data from the Opensky database.