Performance enhancements via experimental optimization for a foil interacting with a vortex wake

Multi-foil flow interactions can lead to enhanced thrust and higher efficiencies compared to their isolated foil counterparts. The performance metrics of multi-foil systems largely depend on their spatial configuration as well as the motion kinematics. Based on these parameters, such as the amplitude of motion and synchrony, the vortex dynamics within the incoming flow field can be tailored for an unsteady foil in interactions to obtain higher thrust and/or propulsive efficiency. In this study we will investigate a four-foil system configured spatially in a diamond shape, inspired by the early work of D. Weihs in 1970s. We will show an experimental optimization procedure by tailoring the motion kinematics and therefore altering the associated vortex dynamics to obtain improved performance for a foil interacting with an unsteady incoming vortex wake. To do so, we will use direct force measurements as well as particle image velocimetry measurements to determine the associated force generation and flow interaction mechanisms.