Abstract
Numerical solutions of the adjoint of the perturbed compressible flow equations are used to seek (and find) small inflow perturbations that bring a directly simulated randomly excited subsonic two-dimensional mixing layer flow into a 'nearby' but much quieter 'state'. This is discussed in the context of common wave-packet or instability wave models of free-shear-flow noise, which are known to qualitatively predict aspects of subsonic jet noise. Emprical eigenfunctions are used to demonstrate that a more regular wave-packet character underlies the pertubed flow, which otherwise appears superficially unchanged. This shows for the first time that the sensitivity of wave-packet type noise sources to subtle details of their space-time structure can, at least in principle, be exploited to effect large (>10dB) reductions in the noise from a nonlinearly active free shear flow.
Original language | English (US) |
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Pages | 14907-14910 |
Number of pages | 4 |
DOIs | |
State | Published - 2005 |
Event | 43rd AIAA Aerospace Sciences Meeting and Exhibit - Reno, NV, United States Duration: Jan 10 2005 → Jan 13 2005 |
Conference
Conference | 43rd AIAA Aerospace Sciences Meeting and Exhibit |
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Country/Territory | United States |
City | Reno, NV |
Period | 1/10/05 → 1/13/05 |
ASJC Scopus subject areas
- General Engineering