Sonic Boom Variability Due to Homogeneous Atmospheric Turbulence

Abstract

This study describes the nondeterministic effect of homogeneous atmospheric turbulence on sonic boom propagation. The Sears-Haack body was calculated in three dimensions by computational fluid dynamics in inviscid flow (Euler) mode to create the near-field pressure wave. The homogeneous atmospheric turbulence field was represented by the finite sum of discrete Fourier modes based on the von Karman and Pao energy spectrum. The sonic boom signature was then calculated by the modified waveform parameter method, considering a random velocity of homogeneous atmospheric turbulence. The results of this study indicated that atmospheric turbulence has a marked influence on sonic boom overpressure during its propagation to the ground. In comparison to the noturbulence condition, we found that the sonic boom decreased in 59% of the cases and increased in 41% of the cases. Thus, homogeneous atmospheric turbulence seems to favor a decrease, rather than an increase, in boom overpressure. In addition, we found that turbulence has a small effect on the propagation path from the flight altitude to the ground. Nonetheless, this small change in the propagation path may result in a variability, of the point at which the sonic boom reaches the ground, of up to 1820 ft in the north-south direction (flight direction) and 115 ft in the east-west direction.

Full-Field Sonic Boom Simulation in Real Atmosphere

“…Therefore, the sonic boom reduction is essential for developing the supersonic airplane and the numerous studies of the sonic boom have been conducted. [1][2][3] It is difficult to predict the propagation mechanism of the sonic boom from the near-field around the airplane to the ground because of the multi-scale nature of the phenomena involving both the near-field and the far-field. Hence, the sonic boom prediction is conducted as follows.…”