Citation

Muhlestein MB, Gee KL, Thomas DC, Neilsen TB. J. Acoust. Soc. Am. 2012; 132(3): 1992.

Affiliation

Department of Physics and Astronomy, Brigham Young University, Provo, UT 84602mimuhle@gmail.com.

Copyright

(Copyright © 2012, American Institute of Physics)

DOI

10.1121/1.4755357

PMID

22979440

Abstract

The extreme sound pressure levels radiated from rocket motors are such that nonlinear propagation effects can be significant. Here, free-field nonlinear propagation has been modeled for noise produced by a GEM-60 solid rocket motor. Measured waveforms were used as inputs into a numerical model based on the generalized Burgers equation. In both temporal and frequency domains the nonlinear predictions are significantly closer to the measured signals than free-field, linear predictions. In the temporal domain, shock coalescence and a transition from the weak-shock regime of propagation to the beginning of the old-age regime are clearly observed in both the nonlinear prediction and the measured data. These phenomena are completely missing in the linear prediction. In the frequency domain, continual transfer of energy upward in the spectrum reduces attenuation of high-frequency components when compared to predictions from the linear model. Various comparisons are made as a function of input distance for two different radiating angles from the rocket plume; these comparisons illustrate the importance of including nonlinear effects in rocket noise propagation modeling.

Language: en