Simulation of the propagation of classical and low booms through turbulent wind fluctuations

Abstract

The present revival of supersonic civil aviation outlines the need to study the propagation of sonic boom through turbulent wind fluctuations known to have an important impact on the noise perceived at the ground. Numerous physical phenomena must be considered: diffraction, non-linearity, absorption, relaxation and turbulence effects. A recent numerical method called FLHOWARD3D is used to simulate the propagation of classical and low-boom wave-forms in a three-dimensional domain of (1 km × 1 km × 1 km) representing a portion of the planetary boundary layer. Wind field is synthesized following a von Kármán energy spectrum. It is found that simulated wave-forms on the ground are close to experimental observations. Low-boom wave-forms show less sensitivity to turbulence. Comparisons between 2D and 3D simulations for peak overpressure statistical distribution show that, in 3D, results are closer to flight tests data than in 2D. Nevertheless the 2D levels are consistent with the experimental levels for around 98% of the cases, and only slightly underestimate the rarest events of highest amplification. Therefore, for this configuration, 2D simulations, though slightly less accurate than3D ones, are computationally much less intensive and can be used for statistical analysis. [This research was conducted as a part of Rumble—EU Grant Agreement 769896.]