Measured turbulence statistics from two NASA sonic boom test campaigns

Abstract

Turbulence in the lower atmosphere can have substantial effects on measured sonic boom waveforms on the ground. These turbulent distortions vary spatially and temporally and are best understood statistically. Simultaneous atmospheric and acoustic data were acquired as part of the NASA Sonic Booms in Atmospheric Turbulence (SonicBAT) and Carpet Determination in Entirety Measurements (CarpetDIEM) tests. Data from these tests, both conducted at NASA Armstrong Flight Research Center, enable a detailed study of atmospheric effects on sonic boom waveforms. The present study expands on previous work [Anderson et al., J. Acoust. Soc. Am. 152, A127 (2022)] by analyzing more booms with additional statistical analyses including metric distributions, standard deviations, and confidence intervals. Results from CarpetDIEM indicate that the confidence interval widths of mean metric levels computed across a seven-microphone array spanning 122 m vary by 1-5 dB, depending on the loudness metric. The effects of peak clipping are also considered, and an analysis is conducted to determine how to best recover from peak clipping for different metrics. [Work supported by NASA Langley Research Center through the National Institute of Aerospace and Analytical Mechanics Associates.]