THE NONLINEAR PROPAGATION OF WAVES THROUGH A TURBULENT ATMOSPHERE
Open Access
Author:
Ward, Evan M
Area of Honors:
Aerospace Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Philip John Morris, Thesis Supervisor Philip John Morris, Thesis Supervisor Dennis K Mclaughlin, Faculty Reader Dr. George A Lesieutre, Faculty Reader Philip John Morris, Thesis Honors Advisor
Keywords:
NONLINEAR PROPAGATION WAVES TURBULENT ATMOSPHERE sonic boom jet noise N wave von karman burgers equation
Abstract:
The nonlinear propagation of waves in a turbulent atmosphere can be described by solutions to the generalized Burgers Equation. A frequency domain algorithm is used to obtain these solutions. Additional terms that describe the effects of fluctuations in temperature and velocity can be included. A random realization of the wind and temperature profile in the atmosphere is chosen for each simulation. Many simulations are then combined to produce the average effect of the turbulence on the propagation. The turbulent fluctuations are calculated from a von Karman spectrum. A computer code was developed that implemented this algorithm to generate the pressure time history at the final range from the pressure time history at the starting range. The new solution method is applied to flattop and ramp sonic boom waveforms and to broadband jet noise. The inclusion of the atmospheric turbulence changes the waveform by adding energy at higher frequencies.
