Delayed Detached-Eddy Simulation of Shock Buffet on Half Wing-Body Configuration

This paper presents a numerical study of the transonic flow over a half wing–body configuration representative of a large civil aircraft. The Mach number is close to cruise conditions, whereas the high angle of attack causes strong separation on the suction side of the wing. Results indicate the presence of shock-wave oscillations inducing unsteady loads that can cause serious damage to the aircraft. Transonic shock buffet is found. Based on exploratory simulations using a baseline grid, the region relevant to the phenomenon is identified and mesh adaptation is applied to significantly refine the grid locally. Time-accurate Reynolds-averaged Navier–Stokes and delayed detached–eddy simulations are then performed on the adapted grid. Both types of simulation reproduce the unsteady flow physics, and much information can be extracted from the results when investigating frequency content, the location of unsteadiness, and its amplitude. Differences and similarities in the computational results are discussed in detail and are also analyzed phenomenally with respect to recent experimental data

Global instability of wing shock buffet

Shock buffet on wings encountered in edge-of-the-envelope transonic flight remains an unresolved and disputed flow phenomenon, challenging both fundamental fluid mechanics and applied aircraft aerodynamics. The question of global instability leading to flow unsteadiness is addressed herein. It is shown for the first time that incipient three-dimensional shock buffet is governed by the dynamics of a single unstable linear eigenmode with its spatial structure describing previously reported buffet cells. An inner-outer Krylov approach is proposed to solve the arising large-scale eigenvalue problem iteratively using shift-and-invert spectral transformation and sparse iterative linear solver. The established numerical strategy with an industrial flow solver means that a practical non-canonical test case at high-$Re$ flow condition can be investigated. A modern wing design with publicly available geometry and experimental data for code validation is studied. The numerical findings can be exploited for routes to flow control and model reduction