Solution of the Lossy Nonlinear Tricomi Equation with Application to Sonic Boom Focusing
Open Access
Author:
Salamone, Joseph Anthony
Graduate Program:
Acoustics
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
July 17, 2013
Committee Members:
Victor Ward Sparrow, Dissertation Advisor/Co-Advisor Anthony A Atchley, Committee Member Thomas B Gabrielson, Committee Member Philip John Morris, Committee Member Dr François Coulouvrat, Special Member
Keywords:
sonic boom focusing caustic absorption dispersion
Abstract:
Sonic boom focusing theory has been augmented with new terms that account for mean flow effects in the direction of propagation and also for atmospheric absorption/dispersion due to molecular relaxation due to oxygen and nitrogen. The newly derived model equation was numerically implemented using a computer code. The computer code was numerically validated using a spectral solution for nonlinear propagation of a sinusoid through a lossy homogeneous medium. An additional numerical check was performed to verify the linear diffraction component of the code calculations. The computer code was experimentally validated using measured sonic boom focusing data from the NASA sponsored Superboom Caustic and Analysis Measurement Program (SCAMP) flight test. The computer code was in good agreement with both the numerical and experimental validation. The newly developed code was applied to examine the focusing of a NASA low-boom demonstration vehicle concept. The resulting pressure field was calculated for several supersonic climb profiles. The shaping efforts designed into the signatures were still somewhat evident despite the effects of sonic boom focusing.