The Use of Actuated Flexible Plates for Adaptive Shock Control Bumps

Adaptive shock control bumps (SCB) aim to retain the performance of static SCV and improve off-design performance caused by variations in shock position due to flowfield unsteadiness and changes in aircraft cruise conditions. An adaptive SCB requires the flexibility to deform and the stiffness to withstand the complex pressure field that is present on the upper surface of a transonic aircraft wing. This study uses a quasi-steady aerostructural solver to design adaptive SCB. Both flexible and actuated plates have been tested in a Mach 1.4 blowdown wind tunnel. The shock structure has been captured over both plates (t=0.4mm) using high speed Schlieren Imaging. Experimental results show that the flexible and actuated plates both have a stabilising effect on the shock, reducing the amplitude of unsteady shock motion from 30 mm to 20 mm and 10 mm respectively. In addition, the actuated plate enabled the shock’s mean stream wise position to be varied by up to 26 mm for an actuator displacement of just 3 mm. The shock holding characteristics were attributed to how changes in surface curvature caused by the cavity pressure and actuation affected the external flow structure and shock structure. The cavity pressure beneath a flexible plate is shown to be a significant design variable with the plate geometry moving from a depression to a protrusion with just 0.1 bar variation.