Kimberly Riegel – kriegel@qcc.cuny.edu
William Costa
George Seaton
Christian Gomez
Queensborough Community College
222-05 56th Avenue
Bayside, NY 11364

Popular version of 2pCA8 – Sonic boom propagation in a non-homogeneous atmosphere using a stratified ray tracing technique’
Presented Tuesday afternoon, November 30, 2019
181st ASA Meeting
Click here to read the abstract

Supersonic air travel could reduce flight times by half, vastly improving long range air travel. To make this type of travel commercially viable, however, the current ban on overland flight would need to be lifted while ensuring residents below are still protected from the high noise levels in the flight paths of these new aircraft. There has been a recent increase in supersonic aircraft investment. United Airlines just invested in 15 supersonic jets provided by BOOM supersonic. These aircraft are expected to fly in 2029 but will remain restricted to over water flight. Lockheed Martin in partnership with NASA is building a low boom demonstrator aircraft. This aircraft is expected to perform some community-based test flights next year. Therefore, a computationally efficient prediction tool that can predict the impact of sonic booms in urban areas would be a useful tool for researchers and legislators.

Previously a ray tracing simulation tool to predict the sound behavior in urban environments was developed. The simulation included the ability to read in 3D renderings of the environments. This made it possible to simulate any complicated shape including detailed buildings and multiple buildings. All surfaces are represented by a mesh of triangular faces. The more complicated the building, the more triangles were required to accurately represent it. The biggest limitation of the code was that it could take several days to complete one simulation of a complicated building. The purpose of this work is to reduce the computational time to make the numerical simulation more accessible while not sacrificing the accuracy of the results.

In order to reduce the computation time for complex geometries the entire environment was cut into horizontal slices. Only the slice where the origin of the ray is considered at a time. This allows for a significant reduction in the number of building facets that needs to be assessed for each step. Figure 1 shows the total building in grey and the slice under consideration in green.

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Figure 1. Representation of a simple building/ray interaction and the vertical slices where the building is segmented.

To determine how the modifications to the code improved the result, several environments were run and compared to those environments for previous version of the code. Table 1 shows the improvements. From the timing of the different versions of the code it is clear that updates to the code have drastically reduced the computation times for complex environments. The resulting pressures at the receivers have no noticeable difference in the pressure results. This will improve the useability of the simulation and make it more convenient to predict sonic booms in urban areas.

Version Timings
12 faces 192 faces 768 faces 3072 faces
Original Python 362 min 610 min 2055 min ~ 5 days
Stratified Building 280 min 229 min 669 min 558 min

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