Impact of atmospheric variations on sonic boom loudness over 10 years of simulated flights.

Abstract

Relative humidity, temperature, and wind along flight paths from a 10-year simulation are used to investigate the effects of the atmospheric conditions on sonic boom loudness generated by the pseudo-Concorde and a low-boom supersonic aircraft using an acoustic wave propagation tool. Global meteorological conditions are simulated using the chemistry-climate model EMAC with ECMWF reanalysis data. The results show that atmospheric conditions lead to a seasonal variation of the perceived level for a N-wave over 10 years of flights, whereas it is difficult to identify the seasonal variation for the low-boom aircraft because the distribution of perceived levels is widely spread. The dominant effect from atmospheric conditions during acoustic propagation is found for the low-boom aircraft cruising at an altitude of 14.478 km. The molecular relaxation effect is dominant for an overpressure reduction at 10 km but does not impact the pressure waveform below 8 km. At altitudes below 8 km, the thermoviscous absorption exclusively influences the variations in pressure rise time. Moreover, acoustic wave propagation through the turbulent field was simulated at a single location. Even though the acoustic wave passed through the same turbulent field in the summer and winter cases, the loudness on the ground differs between them.