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Dynamic Mode Decomposition of a Separated Nozzle Flow with Transonic Resonance

Ragnar Lárusson (Institutionen för tillämpad mekanik, Strömningslära) ; Niklas Andersson (Institutionen för tillämpad mekanik, Strömningslära) ; Jan Östlund
AIAA Journal (0001-1452). Vol. 55 (2017), 4, p. 1295-1306.
[Artikel, refereegranskad vetenskaplig]

Operating convergent–divergent nozzles at low pressure ratios can lead to flow separation. Certain nozzle contours are known to produce a discrete acoustical tone under such conditions that are believed to be generated by a phenomenon known as transonic resonance, which involves a standing pressure wave situated between the separation shock and the nozzle exit plane. This paper reports the findings of a dynamic mode decomposition analysis of a perturbed axisymmetric unsteady Reynolds-averaged Navier–Stokes simulation of a nozzle flow known to exhibit this phenomenon. Two cases of different pressure ratios were studied in depth. The results show that the two cases differ in the shape of the standing pressure wave. The lower pressure ratio produces a standing 3/4 pressure wave, whereas the higher pressure ratio produces a 1/4 wave. In both cases, dynamic mode decomposition modes that match the standing pressure wave shape were found to be the least damped and the most energetic modes of the modes produced by the dynamic mode decomposition algorithm. The frequency of the mode for the lower pressure ratio matched the experimentally observed transonic tone frequency extraordinarily well, whereas the higher pressure ratio case was in fair agreement. The dynamic mode decomposition algorithm captured the transonic frequency for five additional pressure ratios.

Nyckelord: Supersonic nozzle flow, Free-shock separation, Dynamic Mode Decomposition (DMD), Transonic resonance



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Denna post skapades 2017-04-26. Senast ändrad 2017-06-22.
CPL Pubid: 248972

 

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Institutioner (Chalmers)

Institutionen för tillämpad mekanik, Strömningslära (2005-2017)

Ämnesområden

Transport
Rymd- och flygteknik
Strömningsmekanik och akustik

Chalmers infrastruktur

C3SE/SNIC (Chalmers Centre for Computational Science and Engineering)