Toward inclusion of atmospheric effects in the aircraft community noise predictions

Abstract

This paper presents an atmospheric propagation model, based on ray acoustics, that accounts for realistic weather conditions in the evaluation of the noise footprint of an aircraft. Noise sources, obtained using the Ffowcs Williams and Hawkings acoustic analogy applied to scale-resolved flow simulation data, are stored on a hemisphere surrounding the vehicle. These noise sources are propagated using a propagation model that takes into account the vertical variability of air temperature and wind velocity. The electric vertical takeoff and landing aircraft, presented by Casalino, van der Velden, and Romani [(2019). in Proceedings of the AIAA Scitech 2019 Forum, January 7-11, San Diego, CA, pp. 1834-1851], is used as a case study; noise footprints, obtained considering various vertically varying temperature and wind velocity distributions, are compared. It is shown that weather conditions in the acoustic wave propagation can contribute to mismatch up to 4 dBA in the illuminated zone and a significant drop in the refractive shadow zone caused by the vertical air temperature and wind velocity gradients. This work constitutes the first accomplishment in including realistic atmospheric effects in aircraft community noise prediction based on scaleresolved flow simulations. V

Aircraft noise in situations with grazing sound incidence—Comparing different modeling approaches

“…Corresponding variations of the propagation conditions have for example been studied by Plotkin et al (2002), who ran aircraft noise simulations on an hourly basis with specific flight operations and weather conditions and compared resulting noise contours. Fuerkaiti et al (2021) reported "that weather conditions in the acoustic wave propagation can contribute to mismatch up to 4 dB(A) in the illuminated zone and a significant drop in the refractive shadow zone caused by the vertical air temperature and wind velocity gradients." The authors recommended the use of raytracing algorithms in aircraft community noise prediction to reproduce realistic atmospheric effects.…”

Aircraft community noise prediction in 3D environment using Gaussian beam tracing

“…Recently, Fuerkaiti et al [15] developed a two-point 3D eigenray tracer that accounts for sound refraction due to vertical variability of air temperature and wind velocity gradients. Noise footprints of a UAM vehicle cruising at 2 km altitude over a flat ground under di erent weather conditions were evaluated.…”

“…In UYGUR, each Gaussian beam has the same initial amplitude and phase. Inclusion of complex source directivity into the acoustic footprint follows similar steps as described in [15]. In this work, those steps are adapted for the GBT procedures and briefly explained in the following.…”

“…The GBT model was assessed in the previous work from Fuerkaiti et al [15] by comparing it against an exact solution that describes the elementary sound propagation problem in a homogeneous atmosphere over flat terrain. In this work, UYGUR's capability to include complex source directivity is verified by comparing the acoustic footprint of a twin-propeller against reference data that was generated by OptymB-FOOTPRINT tool [28].…”

“…The interference pattern due to the acoustic interaction of these two propellers is clearly visible on the source hemisphere. The reference noise footprint is obtained by projecting the noise levels from the source hemisphere onto the ground receivers using the OptymB-FOOTPRINT tool that propagates the sound rays towards the ground using straight rays [15,29]. The receivers are distributed over a square area of 2.5 km by 2.5 km, as illustrated in Fig.…”