Phononic materials for controlling stalled aerodynamic flows

Adaptive and passive flow control strategies hold great potential for active flow control. Towards this aim, we investigate the fluid-structure interaction (FSI) that arises between phononic materials (PMs) and a separated aerodynamic flow. Phononic materials are designed to have unique frequency-dependent properties that result from their periodic structure. We focus on the interaction between an aerodynamic flow and a partially rigid airfoil with a compliant sub-section on its suction surface. The behavior and motion of this compliant section are dictated by the interplay between the aerodynamic flow and a PM diatomic chain (a spring-mass system with alternating properties). This phononic chain is modeled using two configurations , where each mass either has an additional grounding spring (grounded configuration) or not. We conduct high-fidelity 2D FSI simulations of unsteady flow passing the modified airfoil for (a) a smaller angle of attack (12 degrees), where we aim to trigger vortex shedding from a nominally attached flow via the diatomic chain and (b) a higher angle of attack (15 degrees), where we seek to use the PM to modify the underlying vortex shedding that would be present in the rigid baseline scenario. We quantify how the PM impacts the overall performance changes and affects the FSI by comparison with the standard rigid airfoil case. Moreover, we discuss the underlying mechanisms that drive these interactions by relating dynamics of the FSI system to intrinsic properties of the PM and underlying flow behavior, respectively.