Upstream-travelling acoustic jet modes as a closure mechanism for screech

By D. Edgington-Mitchell, V. Jaunet, P. Jordan, Aaron Towne, Julio Soria, D. Honnery. Journal of Fluid Mechanics, 2018

168 citations recorded by the source corpus.

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.

Subfields: Aerospace Engineering, Computational Mechanics

View Paper: https://www.semanticscholar.org/paper/cd41fa243fb1c49e5872070abf7993c365cacf3e