  Cross-flow turbines, also known as vertical-axis turbines, convert the
kinetic energy in moving fluid to mechanical energy using blades that rotate
about an axis perpendicular to the incoming flow. In this work, the performance
of a two-turbine array in a recirculating water channel was experimentally
optimized across sixty-four unique array configurations. For each
configuration, turbine performance was optimized using tip-speed ratio control,
where the rotation rate for each turbine is optimized individually, and using
coordinated control, where the turbines are optimized to operate at synchronous
rotation rates, but with a phase difference. For each configuration and control
strategy, the consequences of co- and counter-rotation were also evaluated. We
hypothesize how array configurations and control cases influence interactions
between turbines and impact array performance.
