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Contribution to the numerical simulation of turbulent shock-induced separated flows : Application to supersonic over-expanded nozzles flows

Abstract : Shock-induced flow separation and reattachment are encountered in many configurations, such as supersonic inlets, transonic airfoils or rocket nozzles. These phenomena involve complex interactions of boundary layers with compression or expansion waves and exhibit a low-frequency unsteady behaviour which still requires a clear explanation. This study aims at better identifying the physical mechanisms which drive the global structure of these flows and suggesting improved numerical tools in order to predict these more accurately. The appearance of free and restricted separations in supersonic annular jets occuring in thrust optimised contour nozzles operating in overexpanded conditions is more particularly investigated while various hypothesis are tested to explain the evolution of the associated unsteady asymmetric wall pressure field in function of the nozzle pressure ratio. The numerical strategy proposed relies on a realizable extension of the Detached Eddy Simulation, combined with high order shock capturing schemes and an implicit time integration algorithm. This methodology is applied for a wide range of both constant or transient inflow conditions and leads to identify more accurately the appearance of free and restricted separations and the time-varying morphology of the flow during the transition process. For both regimes, the simulation is carried out for long-enough time to perform reliable statistical analysis and azimuthal expansion of the wall pressure field and thus investigate extensively the possible origins of the side-load activities.
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Submitted on : Monday, December 13, 2010 - 3:18:12 PM
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Afaque Shams. Contribution to the numerical simulation of turbulent shock-induced separated flows : Application to supersonic over-expanded nozzles flows. Engineering Sciences [physics]. ISAE-ENSMA Ecole Nationale Supérieure de Mécanique et d'Aérotechique - Poitiers, 2010. English. ⟨tel-00546037⟩

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