Unsteady Transonic Flow over a Transport-Type Swept Wing

The unsteady transonic flow around a flexible transport-type swept-wing configuration with the supercritical airfoil BAC 3-11/RES/30/21 is studied regarding the effects of dynamic shock/boundary-layer interaction involving separated-flow areas on the local fluid-structure coupling at unit Reynolds numbers of around 1.5 x 10(7) m(-1). A fast-responding pressure-sensitive-paint system using pyrene on anodic aluminum binder is applied to measure the unsteady pressure distribution on the entire wing surface, with high spatial and temporal resolution providing a unique view on the spanwise flow development and self-induced shock oscillations. The aeroelastic response of the wing structure is synchronously recorded by videogrammetric deformation measurement. Flow cases with incipient separation and full-scale separation at Mach numbers of 0.86 and 0.92 are compared. A weak shock/boundary-layer interaction with incipient separation has minor effects on the wing structure, despite the occurrence of large pressure fluctuations, whereas the strong interaction involving shock-induced separation results not only in significantly weaker fluctuations in the pressure field, but also in a strong fluid-structure coupling.