Abstract
A study of transonic buffet on the NASA Common Research Model at flight Reynolds numbers is presented. The ability of two different hybrid RANS/LES models as well as the URANS approach for resolving three-dimensional buffet motion was evaluated by means of spectral analysis. Automated Zonal DES and URANS simulations show similar results in terms of buffet frequency and spanwise propagation of buffet cells, whereas the Delayed Detached Eddy Simulation results indicate a strong interaction between flow separation and shock motion. The extracted characteristic frequencies which are associated with transonic buffet are located in a range of Sr = 0.2–0.65 for URANS and AZDES and are therefore in accordance with findings from related recent research. Furthermore, the simulation time series were investigated and a structure of spanwise moving buffet cells with varying convection speed and wavelength could be observed.
Highlights
Safety and efficiency improvements play a major role in the development of modern transport aircraft
The present study focuses on the capability of different simulation approaches to reproduce three-dimensional transonic buffet
The focus was on the investigation of threedimensional transonic buffet, and the selection of a proper hybrid RANS/LES simulation approach for this complex phenomenon
Summary
Safety and efficiency improvements play a major role in the development of modern transport aircraft. Since cruise flight in the transonic regime is the primary part of a typical flight connection, the investigation of the aerodynamics in this phase is of special interest. This requires a better understanding of the flow effects determining its boundaries. The accurate prediction of aerodynamic phenomena that occur under these conditions remains a challenging task due to the occurrence of locally supersonic flow above the upper surface of the wing and the associated shocks and shock–boundary layer interaction. If the Mach number or the angle of attack are increased, these phenomena can result in transonic buffet, a complex unsteady shock motion coupled
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