Validation of numerical predictions of sonic boom metric variability due to turbulence

Abstract

Atmospheric turbulence scatters the sonic boom wavefront created by supersonic aircraft, causing random variations in the waveforms and spectra measured at the ground. To help assess the impact of turbulence, a time-domain algorithm based on the nonlinear KZK propagation equation has been developed which simulates turbulent fields via an approximate atmospheric theory. Two sets of recent supersonic overflight measurements at the NASA Neil A. Armstrong Flight Research Center and the Kennedy Space Center offer datasets which have been used to quantify the algorithm’s utility to simultaneously model atmospheric turbulence, nonlinearity, and absorption. The field campaigns simultaneously recorded measurements of both sonic boom waveforms along linear microphone arrays and also turbulence quantities suitable for use in the algorithm. The algorithm’s performance in predicting the measured variation of sonic boom metrics will be discussed. [Work supported by NASA via a subcontract from KBRwyle.]