A parametric study on the perfprmance of tidal stream VAT using a simplified flow model

The effect of the design parameters of the vertical axis turbines used for the tidal current power generation is investigated by using a simple two-dimensional flow model. The power coefficient was calculated as a function of the tip-speedratio, with varying the turbine radius, the blade´s chord length and the pitch angle, while the lift and drag characteristics of a known symmetric hydrofoil is taken as an approximate function. The variable pitch showed to improve the overall efficiency of the turbine including better cut-in characteristics and some reduced shaft excitation.