Delayed detached eddy simulation of the end-effect regime and side-loads in an overexpanded nozzle flow |
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Authors: | Sébastien Deck |
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Institution: | (1) Applied Aerodynamics Department, ONERA, 8 rue des Vertugadins, 92190 Meudon, France |
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Abstract: | The separated flow in an overexpanded nozzle featuring a restricted shock separation is investigated numerically using delayed
detached eddy simulation and compared with the experimental data of Nguyen et al. (Int J Flow Turbul Combust 71(1):161–181,
2003). First, the enormous cost of a Large Eddy Simulation for such a nozzle flow is assessed before being performed to motivate
the practical need for using an hybrid RANS/LES method. The calculation is then used to investigate the “end-effect” regime
which involves a strong global unsteadiness with very large amplitude fluctuations of about 15–20% of nozzle divergent length.
The flow regime is characterized by high wall pressure fluctuations which are hopefully nearly axisymmetric. The main properties
(rms levels, amplitude of displacement of the separation) of the motion are rather well reproduced by DDES compared to the
experiment. However, a major difference lies in the frequency of the computed motion which is higher than in the experiment.
This major discrepancy is currently not explained by the author. The properties of the side-loads are also briefly discussed.
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Keywords: | Delayed detached eddy simulation Separated flow Unsteady Nozzle Restricted-shock-separation Side-loads |
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