Cross-flow helical turbine for energy production in reversing tidal and ocean currents

This paper presents an investigation into the performance of a helical water turbine in both computer simulated and physical tests. Power curves were developed for both physical and virtual models, as well as angular velocity and power responses over time. The virtual model was tested with a PID controller to simulate real-world speed control in power generation by varying turbine loading. The virtual model responded well to virtual PID control, suggesting a physical model could be controlled by varying the brake torque, or applied load. Both models displayed some small variance in rotational speeds and torque over time, but values tended to oscillate between two asymptotic values. Though neither the virtual nor physical models approached previously demonstrated efficiencies of helical water turbines, both models agreed that peak power generation occurs at approximately 60% of freewheel angular velocity for the stream speeds tested. It is suggested that higher efficiencies may be obtained by changing turbine configuration, and in the case of virtual models, using an even finer resolution mesh for computational fluid dynamics analysis.