| Autor: |
M. Fiore, H. Parisot-Dupuis, B. Etchebarne, R. Gojon |
| Přispěvatelé: |
Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE), Office National d'Etudes et Recherches Aérospatiales - ONERA (FRANCE) |
| Jazyk: |
angličtina |
| Rok vydání: |
2022 |
| Předmět: |
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| Popis: |
A large variety of flow configurations involve an aero-acoustic coupling and the complexity of the interaction can make the analysis difficult. In the purpose to decompose these flows in simpler phenomena, the spectral proper orthogonal decomposition (SPOD) algorithm can be used. Compared to POD, this method adds up a discrete Fourier transform before the singular value decomposition. A theoretical framework for the weighting of the flow field variables used in the SPOD has been proposed to identify hydrodynamic modes by Schmidt et al. However, in flow configurations where both the hydrodynamic and acoustic fields interact, without additional data processing, only hydrodynamic modes that are generally dominants would be identified by the SPOD. This paper proposes a general framework based on a few pre-processing steps applied to the input aero-acoustic fields to facilitate the identification of both the hydrodynamic and acoustic fields by the SPOD, the purpose being to analyze how the hydrodynamic waves lead to the acoustic ones and the possible feedback process. This framework is applied to large-eddy simulations of supersonic ideally expanded impinging planar jet of infinite extent characterized by different nozzle-to-plate distances and incidence angles of the flat plate. The analysis shows that the SPOD algorithm is able to capture two important aero-acoustic feedback loops of impinging jet configurations: the one closed by sound waves traveling upstream (related to the jet impingement on the flat plate) and the one characterized by neutral wave modes of the jet shear layer itself. The analysis has also shown that the symmetrical/anti-symmetrical acoustic patterns radiated with respect to the jet main axis and due to the jet impingement are mainly correlated to the axial velocity fluctuations structures in the jet for the normally impinging cases. For the cases with flat plate incidence, the acoustic radiated is mainly correlated to vertical velocity fluctuations structures developing in the upper shear layer of the jet. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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