On the Dispersion Mechanism of the Flutter Boundary of the AGARD 445.6 Wing

Abstract

The variation in the flutter boundary of the AGARD 445.6 wing in transonic and low supersonic states is an unresolved issue in the field of aeroelasticity. This well-known variation phenomenon is mainly reflected in three aspects: 1) the discrepancy between the computational and the experimental results; 2) the large dispersion of the computational results between different solvers; 3) the sensitivity of calculated flutter boundary to many factors, such as computational fluid dynamics discretization scheme and spatial resolution. However, the root cause of this phenomenon is not clear yet. In this paper, the physical mechanism of the dispersion phenomenon is investigated in the case of using the reduced-order model (ROM)–based aeroelastic analysis model. A dominant least stable flow mode, which has an important effect on the flutter characteristic, is captured by the ROM. The variation in the damping of this dominant flow mode significantly affects the flutter boundary or even changes the instability branch of the structural mode. By adjusting the aerodynamic damping of the dominant flow mode, the flutter boundary curve under the aerodynamic damping variation is predicted. When comparing with the available literature results, the scattered literature data fall around the predicted curve, which indicates that the sensitivity of the damping of the dominant flow mode is the root cause for the dispersion phenomenon of the flutter boundary.