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- Title
Upstream-travelling acoustic jet modes as a closure mechanism for screech.
- Authors
Edgington-Mitchell, Daniel; Soria, Julio; Honnery, Damon; Jaunet, Vincent; Jordan, Peter; Towne, Aaron
- Abstract
Experimental evidence is provided to demonstrate that the upstream-travelling waves in two jets screeching in the A1 and A2 modes are not free-stream acoustic waves, but rather waves with support within the jet. Proper orthogonal decomposition is used to educe the coherent fluctuations associated with jet screech from a set of randomly sampled velocity fields. A streamwise Fourier transform is then used to isolate components with positive and negative phase speeds. The component with negative phase speed is shown, by comparison with a vortex-sheet model, to resemble the upstream-travelling jet wave first studied by Tam & Hu (J. Fluid Mech., vol. 201, 1989, pp. 447-483). It is further demonstrated that screech tones are only observed over the frequency range where this upstream-travelling wave is propagative.
- Subjects
COMPRESSIBLE flow; SOUND waves; REYNOLDS number
- Publication
Journal of Fluid Mechanics, 2018, Vol 855, pR1
- ISSN
0022-1120
- Publication type
Article
- DOI
10.1017/jfm.2018.642