Laminar boundary layer separation over a fluttering panel induced by an oblique shock wave

Panel flutter in the presence of oblique shock waves and the associated shock wave/boundary-layer interaction have been identified as one of typical phenomena in the design and optimization of air-breathing, high-speed flight vehicles. The current study investigates this phenomenon using a previously considered two-dimensional model where an elastic panel with both ends pinned is impinged at the mid-point by an oblique shock wave with specified strength. An in-house code was used to solve the Euler or the full viscous compressible Navier-Stokes equation and nonlinear structural dynamics of the panel, where the conventional serial staggered algorithm was adopted for the fluid-structure interaction. As compared with previous studies of this topic, we focus on the effect of surface velocity feedback (i.e., using boundary blowing and suction for flow control), as well as the effect of the upstream boundary layer thickness, on the panel's dynamic behavior, surface pressure distribution, and boundary-layer separation. The results show that for inviscid flow, boundary control with feedback gain above one can suppress the panel vibration; however, this effect is not clear for viscous flow, where feedback gain below one has some effect on attenuation of vibration. Further study shows that the panel velocity based control introduces a phase shift for the pressure in the inviscid flow as a damping effect, but the effect is not as strong in the viscous flow. Finally, the boundary layer thickness has a non-monotonic effect on the panel flutter and flow separation. At intermediate thicknesses considered here, the panel flutter is reduced and separation becomes less oscillatory. (C) 2019 Elsevier Ltd. All rights reserved.