As part of the project iGREEN, a new experimental setup was tested for the first time in the TWG adaptive test section. The experiments were designed to analyse forced responses similar to gust and tail buffet problems.
The first measurement campaign (FLIB-1) was designed to examine the suitability of a vibrating NACA0010 rectangular wing as a gust or interference generator for a future downstream 3-D wing. Particle image velocimetry (PIV) was applied at the installation point of the active wing to visualise unsteady flow and to subsequently analyse the unsteady wake field and the expansion of the downstream vortices induced by the torsional vibration of the upstream gust generator. The image at the bottom right shows the flow amplitudes of the vertical velocities induced downstream across the height of the central tunnel section at Mach 0.70 and a=0 degrees during PIV and RANS simulation.
The consistency can be considered very good, especially in view of the extremely sophisticated numerical modelling of the convective turbulence transport from the gust generator to the location of the PIV light section.
Other measurement campaigns conducted on the test rig during the iGREEN and ALLEGRA projects analysed how excitation of the rectangular wing impacts response behaviour of the elastic, aerodynamically stable wing located downstream.