Atmospheric vertical wind effects and their impact on sonic boom

Abstract

The one-dimensional augmented Burgers' equation has been generally used for nonlinear lossy sonic boom propagation. This equation models the effects of nonlinearities, loss mechanisms such as absorption and dispersion due to molecular relaxation and thermoviscous dissipation, and geometric spreading through ray tube areas including Blokhintzev scaling as well as atmospheric stratification. Traditionally, atmospheric winds are accounted for by using horizontal wind components varying in magnitude as the sonic boom pressure waveform propagates from near the aircraft toward the ground. Vertical wind components, though present in the real atmosphere, are generally ignored because they are usually much weaker compared to the horizontal components. However, for long propagation distances, such as in the case of secondary booms or speeds at or slightly below Mach cut-off, vertical winds could play a role in changing the location and intensity of sonic booms. This work will update sBOOM, an augmented Burgers' equation solver, to include the vertical component of atmospheric winds. The sonic boom ground signatures and other relevant data will be compared against those obtained ignoring vertical wind components. Such differences will be discussed and documented for cases which may include shaped low-boom as well as strong shock signatures.