Dynamic Roughness Applied to Boundary Layer Control

Physical Sciences (PSI) with its partners, West Virginia University (WVU), Iowa State University (ISU) and Pennsylvania University (PSU), successfully demonstrated the feasibility of using dynamic roughness for boundary layer control on a wing. In Phase I the team developed the theoretical models and CFD tools necessary to understand the underlying phenomenology, and validated the results using sophisticated experimental setups. In Phase II PSI, WVU and ISU will refine the theoretic models and CFD tools to create high-fidelity flow simulations which will be used to quantify the performance of dynamic roughness of various geometries actuated across a range of amplitudes and frequencies. A Dynamic Roughness Boundary Layer Control System (DRBLCS) will be developed and tested on SUASs in wind tunnel and free-flight experiments. The ultimate goals of the program are to develop a firm understanding of how dynamic roughness controls the boundary layer; develop the materials, components and systems necessary to allow dynamic roughness appliqués to be applied to aerospace vehicles; and commercialize the technology for application on military and civilian systems. BENEFIT: Active boundary layer control can be used to enhance an aircraft’s performance, agility and noise control. While numerous active boundary layer concepts have been proposed and tested, all have suffered from issues relating to complexity, power requirements, robustness and mass. PSI’s proposed Dynamic Roughness Boundary Layer Control System is different from other BL control technologies in that it has been shown to be capable of controlling boundary layer separation and preliminary power and mass estimates indicate that it is appropriate for vehicles as small as MAVs. In addition to enhancing the performance of conventional aircraft designs, dynamic roughness may be an enabling technology for unconventional designs based on flapping wings. Flying insects for example rely on complex vortex generation over their wings for the efficient generation of lift. To make an artificial insect using engineered materials fly efficiently, PSI is investigating using dynamic roughness to aid in vortex formation and control. Other military and commercial applications of dynamic roughness include: drag reduction of ships and submarines, flow noise control in pipes, switchable surface traction and tactile feedback systems.