This paper presents a numerical investigation of the influence of solidity on the hydrodynamics of a generic tidal cross-flow turbine. Flows through two- and four-bladed turbines were simulated at a high laboratory Reynolds number, O(105). The corresponding turbine solidities were 0.019 and 0.038.
It was found that increasing the number of blades led to an increase in the maximum power coefficient from 0.43 to 0.53. Furthermore, the power curve shifted to a lower range of tip speed ratios due to an increase in flow impedance, and hence reduced streamwise flow velocity, that resulted from the higher turbine solidity.
It was observed that dynamic stall occurred at the lowest tip speed ratios. However, its net effect on turbine performance was found to be negative.