Three-Dimensional Rectangular Duct Code with Application to Impedance Eduction
2002; American Institute of Aeronautics and Astronautics; Volume: 40; Issue: 2 Linguagem: Inglês
10.2514/2.1663
ISSN1533-385X
Autores Tópico(s)Wind and Air Flow Studies
ResumoA zero flow, fully three-dimensional, variable impedance, rectangular duct aeroacoustics code that spans the frequency spectrum of interest in duct liner research is developed. The governing equations and boundary conditions in the duct are solved numerically using the finite element methodology. The methodology makes use of a state-of-the-art, sparse equation solver to obtain the capability to study high-frequency sound waves that may require millions of grid points for resolution. Noise suppression levels predicted from the code are in excellent agreement with those obtained from mode theory. The single-processor performance of the solver, relative to that of the more commonly used band solver, increases with frequency. At a frequency of 17 kHz, the band solver is 4.25 times slower and consumes 2.5 times more memory than the fully sparse equation solver. The duct aeroacoustics code is combined with an optimization algorithm and used successfully to educe the impedance spectrum of a ceramic liner. The primary problem with using the methodology to perform optimization studies at frequencies above 14 kHz is excessive central processor unit time. The results support the recommendation that research be directed toward exploitation of the multiprocessor capability of the solver to further reduce central processor unit time.
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