Efficiency of Marine Hydropower Farms Consisting of MultipleVertical Axis Cross-Flow Turbines

Abstract

This study focuses on the Achard turbine, a vertical axis, cross-flow, marine current turbine module. Similar modules can be superposed to form towers. A marine or river hydropower farm consists of a cluster of barges, each gathering several parallel rows of towers, running in stabilized current. Two-dimensional numerical modelling is performed in a horizontal cross-section of all towers, using FLUENT and COMSOL Multiphysics. Numerical models validation with experimental results is performed through the velocity distribution, depicted by Acoustic Doppler Velocimetry, in the wake of the middle turbine within a farm model. As long as the numerical flow in the wake fits the experiments, the numerical results for the power coefficient (turbine efficiency) are trustworthy. The overall farm efficiency, with respect to the spatial arrangement of the towers, was depicted by 2D modelling of the unsteady flow inside the farm, using COMSOL Multiphysics. Rows of overlapping parallel towers ensure the increase of global efficiency of the farm.

Performance and Flow Field of a Gravitation Vortex Type Water Turbine

“…Many large-scale conventional hydraulic power generations mainly use medium-or high-heads and water turbines [1,2] for conduits, such as the Francis water turbine. Recently, however, as public consciousness about renewable energies has risen, the demand for small-scale hydraulic power generation with a water turbine [3][4][5][6][7] for open channels has been increasing, with the use of so-far unused common rivers or waterways that have low heads and low flow rates.…”