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Simulations of sonic boom ray tube area fluctuations for propagation through atmospheric turbulence including caustics via a Monte Carlo methodA theory which gives statistical predictions for how often sonic booms propagating through the earth's turbulent boundary layer will encounter caustics, given the spectral properties of the atmospheric turbulence, is outlined. The theory is simple but approximately accounts for the variation of ray tube areas along ray paths. This theory predicts that the variation of ray tube areas is determined by the product of two similar area factors, psi (x) and phi (x), each satisfying a generic harmonic oscillator equation. If an area factor increases the peak acoustic pressure decreases, and if the factor decreases the peak acoustic pressure increases. Additionally, if an area factor decreases to zero and becomes negative, the ray has propagated through a caustic, which contributes a phase change of 90 degrees to the wave. Thus, it is clear that the number of times that a sonic boom wave passes through a caustic should be related to the distorted boom waveform received on the ground. Examples are given based on a characterization of atmospheric turbulence due to the structure function of Tatarski as modified by Crow.
Document ID
19920024634
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Sparrow, Victor W.
(Pennsylvania State Univ. University Park, PA, United States)
Pierce, Allan D.
(Pennsylvania State Univ. University Park, PA, United States)
Date Acquired
September 6, 2013
Publication Date
October 1, 1992
Publication Information
Publication: NASA. Langley Research Center, High-Speed Research: Sonic Boom, Volume 1
Subject Category
Acoustics
Accession Number
92N33878
Funding Number(s)
CONTRACT_GRANT: NAG1-947
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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