United States Department of Transportation
i
Sonic Boom Prediction Workshop 3: Propagation Modeling Using PCBoom
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2020-06-15
[PDF-2.29 MB]
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Abstract:The PCBoom suite of tools was used to model atmospheric propagation cases and the optional focus case as part of the 3rd AIAA Sonic Boom Prediction Workshop. The Focused Boom module FOBoom version 6.8b was used to complete ray tracing calculations using CFD pressure data as the source. Lossy propagation was modeled using PCBoom’s interactive Burgers equation solver, PCBurg, and final results were obtained with the batch analysis tool HeadlessBurgers. Modifications to the latter tool were made to add B-weighted sound exposure level to the output. The effects of sampling rate, time-step factor, and other factors on model results were investigated. Lateral cutoff angles were refined by finely incrementing azimuth angles and examining propagation paths and ground metrics near cutoff. The optional focus case, in which the vehicle trajectory included acceleration, was also modeled using PCBoom. An interactive program (RayCau) was used to generate ray diagrams showing the caustic and the delta-tangent ray to confirm the focus condition, and to facilitate identification of the ray and signature for input to the Lossy Nonlinear Tricomi Equation (LNTE) solver. PCBurg was used to obtain the lossy signature at the delta tangent position. Finally, the LNTE module was used to compute signatures in the vicinity of the focal zone.
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Content Notes:This material is declared a work of the U.S. Governemtn and is not subject to copyright protection in the United States.
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