ENGINEERING ANALYSIS INC.
TURBULENT PRESSURE FLUCTUATIONS
Under Phase I and Phase II SBIR contracts with NASA, we developed a means of predicting the rms turbulent pressure fluctuation on the surface of an aerospace vehicle, based on the mean flow field, as generated by conventional CFD programs. This study was the catalyst leading to the Seismic Tornado Detection (STD) concept. Four different flow conditions were considered as follows:
- two-dimensional incompressible
- three-dimensional incompressible
- two-dimensional compressible
- three-dimensional compressible
The basic equations governing pressure fluctuations for these flow conditions were derived. Proceeding from two-dimensional incompressible flow to three-dimensional compressible flow, the equations grow increasingly complex. Numerical procedures were devised to solve such equations.
Perhaps the most important numerical procedure developed was the significant component/term logic, which filtered out insignificant components/terms from the numerical process. Without such a technique the computational effort would have increased several orders of magnitude. For the case of compressible flow, such a level of effort would probably have exceeded available computer resources.
Based on the numerical procedures noted, we developed the SURPRESS (Surface Pressure) software. This software is the most recent in a series of turbulence software packages developed by us.
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