Abstract
The low/zero head river current energy converter represents an attractive way of producing electricity for rural areas with nearby rivers and a shift towards reliable no-dam technology. This work presents a new design of a low/zero head river current energy converter. Different from the traditional fixed-pitch turbines that operate at angles of attack that either prevent power extraction or stall the blade during a portion of their revolution, the horizontally deployed pitch adjustable turbine (cycloidal cross-flow turbine) features varying blade pitch throughout each revolution to maximize the energy harvest. The optimal hydrodynamic design of this concept is explored by adopting an optimization routine for determining the pitching scheme and running hydrodynamic analysis via CFD in a domain with two sets of sliding interfaces. Simulations of both a one-section turbine and a three-section turbine yield similar averaged values of power coefficient of about 0.49, significantly higher than other turbine designs. The three-section turbine produces less oscillatory load transmitted to the turbine structure and benefits from enlarging the turbine lifespan in long-term operations. For the current three-section design, an optimal Tip-Speed Ratio is recommended as the design condition. Increased turbulence level of the river current results in decreased turbine efficiency.