Assessing the Influence of Operational and Geometric Parameters on the Hydrodynamic Performance of Vertical-axis Marine Current Turbines

The hydrodynamic behavior of vertical-axis marine current turbines is analyzed through a multivariate study considering various combinations of blade numbers, chord lengths, and rotor radii across 16 geometrical configurations operating over a wide range of tip speed ratios (TSRs) using two-dimensional computational fluid dynamics (CFD) simulations. The results reveal that reducing the number of blades from 6 to 3 at a given solidity can increase the power coefficient by up to 7.9%. However, this performance gain comes at the cost of a considerable increase in torque fluctuation amplitude, which in water applications could affect structural loading and operational stability. While these results align well with the literature in aggregate, the present study provides additional insights by reconstructing lift and drag polars using an advanced methodology to extract the instantaneous angle of attack of the flow approaching the blades. This approach provides not only a more in-depth analysis of blade hydrodynamics under unsteady conditions but also contextualizes the impact of the Reynolds number and chord-to-radius (c/R) ratio on turbine performance through the virtual cambering effect. The results demonstrate that higher Reynolds numbers enhance resistance to flow separation, while larger chord lengths amplify the virtual curvature effect. These findings improve the understanding of the interplay between key geometric and operational parameters, offering valuable guidance for optimizing vertical-axis turbine design in marine energy applications.A simple local watertight plate adjustment in the high-risk area can improve the safety of the ship