Zonal-Detached Eddy Simulation of Transonic Buffet on a Civil Aircraft Type Configuration
This paper presents a transonic buffet simulation on a half wing/body rigid model at a realistic Reynolds number. The modelling approach retained is a Zonal-DES approach which allows attached boundary layers to be protected and a rapid switching into LES
- PDF / 1,466,178 Bytes
- 10 Pages / 430 x 660 pts Page_size
- 111 Downloads / 187 Views
Abstract This paper presents a transonic buffet simulation on a half wing/body rigid model at a realistic Reynolds number. The modelling approach retained is a Zonal-DES approach which allows attached boundary layers to be protected and a rapid switching into LES mode in the separated areas. Transonic buffet phenomenon is a challenging case for DES type simulations since the separation point is unstable during time and the separation remains closed to the skin of the model. The simulation was performed on an adapted mesh and comparisons with experiments are carried out. It is shown that the mean field is accurately predicted with ZDES while the present RANS calculations failed to reproduce this shape of the separated area. The results also provide an insight into the unsteady nature of the flow.
1 Introduction The transonic buffet is an aerodynamic phenomenon which results in a large scale self-sustained motion of the shock over the surface of the airfoil linked to a “pulsation” of a massive separation. The onset of this phenomenon is not related to any fluid/structure interaction, although it is inevitable that some structural deformation may be present. Indeed, the unsteady behavior of the flow may lead to structure vibrations named “buffeting” which can lead to fatigue failure. Design standards for aircrafts limit the intensity of the buffeting phenomenon since the large variation of lift associated with buffet limits the cruising speed of aircrafts and 30% of lift marging are necessary between the cruise conditions and the onset of buffeting. Then, the prediction of such phenomenon thanks to CFD tools around a whole civil aircraft is a problem of outstanding importance. Hence, there is considerable interest in numerical approaches solving unsteady averaged Navier-Stokes equations (U)RANS to predict this type of unsteady “harmfull” phenomenon. Past researches (Furlano, 2001, Caruelle, 2000 and Bartels, 1997) mainly focused on aerodynamic buffet on a two-dimensional rigid airfoil which is characterized by a periodic motion of the shock over the airfoil. As an example, complete study (turbulence models, numerical schemes) of (U)RANS calculations concerning the OAT15A supercritical airfoil (Jacquin, 2005) has been recently performed by Brunet (2003). His study shows that (U)RANS calculations are able to predict quite well the main properties of the flow (rms, pressure distribution) but often need to increase the angle of attack in the calculation compared to the experimental value. The transonic buffet on the OAT15A airfoil was also investigated by Deck S.-H. Peng and W. Haase (Eds.): Adv. in Hybrid RANS-LES Modelling, NNFM 97, pp. 182–191, 2008. © Springer-Verlag Berlin Heidelberg 2008 springerlink.com
ZDES of Transonic Buffet on a Civil Aircraft Type Configuration
183
(2005) using a Zonal-Detached Eddy Simulation (ZDES) approach. The main features including spectral analysis were compared with experimental data and used to discuss a possible aeroacoustic feedback process. Finally, the numerical simulation of
Data Loading...
