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Brussels, Belgium

Hirsch C.,Numeca International
28th AIAA Applied Aerodynamics Conference | Year: 2010

Two representative test cases of shock wave boundary layer interactions (SWBLI) were simulated by a large number of groups, with models including RANS and LES models. The paper will review the main trends of the presented results, identifying strengths and weaknesses of turbulence models, in view of the three-dimensionality of the flow and the extend of the separation region. Trends of the CFD results are discussed and recommendations for future actions are suggested. © 2010 by Charles Hirsch.

Di Francescantonio P.,Scientific and Technical Software | Hirsch C.,Numeca International | Ferrante P.,Numeca International | Isono K.,NUMECA Japan
SAE Technical Papers | Year: 2015

A new method called Adaptive Spectral Reconstruction (ASR) for the stochastic reconstruction of broadband aeroacoustic sources starting from steady CFD analyses is presented and applied to the evaluation of the noise radiated by a model automotive side mirror. The new approach exploits some ideas from both SNGR and RPM, and for some aspects can be considered as a sort of mixing between the two methods since it permits to reconstruct both the frequency content of the turbulent field (as done by SNGR) and the spatial cross correlation (as done by RPM). The turbulent field is reconstructed with a sum of convected plane waves, but two substantial differences are introduced in respect of SNGR. The first difference concerns the spatial variation of the parameters that define each wave, that depends on the wavelength of each wave, rather than being kept constant or related to the CFD correlation length. The second innovative aspect is the usage of a dedicated full hexa adaptive mesh that is refined in function of the expected local correlation length, ensuring that the mesh be enough refined to capture the relevant acoustic length scales. The method is here applied to the evaluation of a classical side mirror model test case, and results are presented in terms of comparisons with measurements for both in plane and out of plane microphones. Visualizations of reconstructed acoustic sources are also presented. Copyright © 2015 SAE International.

Wunsch D.,Numeca International | Hirsch C.,Numeca International | Nigro R.,University of Mons | Coussement G.,University of Mons
Proceedings of the ASME Turbo Expo | Year: 2015

The NASA rotor 37 is investigated accounting for as many as 9 simultaneous operational and geometrical uncertainties. The combined influence of uncertainties on input quantities such as the total inlet pressure, static outlet pressure, tip gap or leading and trailing edge angles on output quantities is studied. These simulations provide results which go far beyond the standard deterministic simulation. A probabilistic collocation method in combination with a sparse grid quadrature is introduced into the software suite FINETM propagating combined operational and geometrical uncertainties in complex 3D CFD simulations. The modification of the parameterized geometry and the consequent re-meshing is provided by a fully automatic tool, which also couples with the flow solver and provides post-treatment routines. It is this automation, which makes this kind of study feasible. A manual modification of geometry, manual meshing and simulation set-up accounting for a multitude of simultaneous uncertainties is simply unfeasible for as many as hundreds of complex 3D turbo-machinery simulations. This work represents thus a break-through in the uncertainty management towards the application of uncertainty propagation in the daily engineering practice. Copyright © 2015 by ASME.

Bruce P.J.K.,University of Cambridge | Bruce P.J.K.,Imperial College London | Babinsky H.,University of Cambridge | Tartinville B.,Numeca International | And 2 more authors.
AIAA Journal | Year: 2011

An experimental and numerical investigation into transonic shock/boundary-layer interactions in rectangular ducts has been performed. Experiments have shown that flow development in the corners of transonic shock/boundary-layer interactions in confined channels can have a significant impact on the entire flowfield. As shock strength is increased from M∞ = 1:3 to 1.5, the flowfield becomes very slightly asymmetrical. The interaction of corner flows with one another is thought to be a potential cause of this asymmetry. Thus, factors that govern the size of corner interactions (such as interaction strength) and their proximity to one another (such as tunnel aspect ratio) can affect flow symmetry. The results of the computational study show reasonable agreement with experiments, although simulations with particular turbulence models predict highly asymmetrical solutions for flows that were predominantly symmetrical in experiments. These discrepancies are attributed to the tendency of numerical schemes to overprediction corner-interaction size, and this also accounts for why computational fluid dynamics predicts the onset of asymmetry at lower shock strengths than in experiments. The findings of this study highlight the importance of making informed decisions about imposing artificial constraints on symmetry and boundary conditions for internal transonic flows. Future effort into modeling corner flows accurately is required. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Deconinck T.,Numeca International | Deconinck T.,Aeroacoustic Group | Capron A.,Numeca International | Hirsch C.,Numeca International | Ghorbaniasl G.,Vrije Universiteit Brussel
International Journal of Aeroacoustics | Year: 2012

An innovative aeroacoustic prediction method for Contra-Rotating Open Rotors (CROR) based on the nonlinear harmonic method (NLH) for the CFD computations and on the Ffowcs Williams and Hawkings (FW-H) equations for the far-field acoustic propagation is described. This method is tested on a generic 8 × 8 puller CROR at typical take-off conditions. The outstanding efficiency of the prediction method in terms of CPU cost is demonstrated in this study. An analysis of the aerodynamic interactions between the two rotors as well as of the aeroacoustic field radiated in the far-field is presented, allowing for an improved understanding of noise generation mechanisms.

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