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REFLECTION AND SCATTERING OF SOUND BY FLAMES.
Final technical rept.,
PHILCO NEWPORT BEACH CALIF AERONUTRONIC DIV
Pagination or Media Count:
The report describes acoustic measurements taken with various laboratory flame systems. These involved 1 determination of the acoustic scattering and attenuating characteristics of an open premixed propane flame, 2 determination of the attenuation of open solid propellant flames containing varying aluminum concentrations, and 3 determination of the acoustic combustion noise emission characteristics of various solid propellants. The acoustic attenuation, measured with a collimated sound beam propagating through various open gas and solid propellant flames, was extremely high. The observed attenuation coefficient was at least two orders of magnitude in excess of that attributable either to classical viscous and thermal conductive losses or to molecular relaxation losses. Acoustic scattering measurements indicated intense lateral scattering to be the probable cause of the high attenuation. An acoustic scattering theory was developed in conjunction with a postulated model for a turbulent flame. The acoustic combustion noise generated by burning small slabs of solid propellant possessed a continuous broadband spectrum of high amplitude. Author
APPROVED FOR PUBLIC RELEASE