Feasibility studies for the installation of Plasma Synthetic Jet Actuators on the skin of a morphing wing flap

A morphing structure can be considered as the result of the synergic integration of three main systems: the structural system, based on reliable kinematic mechanisms or on compliant elements enabling the shape modification, the actuation and control systems, characterized by embedded electromechanical actuators and robust control strategies, and the sensing system, usually involving a network of sensors distributed along the structure to monitor its state parameters. Technologies with ever increasing maturity level are adopted to assure the consolidation of products in line with the aeronautical industry standards and fully compliant with the applicable airworthiness requirements. In the framework of the CleanSky2, one of the largest research projects ever funded by the European Union, a novel multi-modal camber morphing flap was conceived for the enhancement of the aerodynamic performances of the next generation green regional aircraft. Thanks to different morphing modes, the shape of the flap can be suitably adapted in order to preserve an optimal configuration as the aircraft trim parameters change according to the specific flight phase (take-off, climb, cruise, descent, landing). To further improve the benefits brought by such technology on the wing aerodynamic efficiency, an active flow control system based on plasma synthetic jet (PSJ) actuators was investigated for a potential installation on the upper skin of the flap. PSJ actuators, or Sparkjets, are able to produce very high jet velocities, without the aid of any moving parts, affecting the structure of the flow-field to be controlled and allowing a positive variation of the aerodynamic forces on the aircraft, with a modest power consumption. This work is focused on the two main aspects related to the feasibility of PSJ actuators integration into the adaptive flap skin: the thermal and electromagnetic interferences of the actuators with the other electronic equipment of the flap. Experimental measurements were carried out to characterize the thermal and the electromagnetic fields induced by the operating device into the surrounding structure. A simplified test article was designed and manufactured to support all experimental activities while being fairly representative of the actual PSJ-skin assembly. Test results allowed for a definition of the safety-critical areas for the installation of flap actuation, control and sensing systems.