Numerical study of straight-bladed Darrieus-type tidal turbine

Abstract

This paper presents developments in numerical simulations of a cross-flow vertical-axis marine current turbine (straight-bladed Darrieus type) with particular emphasis on rotor-performance prediction and hydrodynamic loads for structural design calculations. This study initially used theoretical double-multiple-streamtube models, followed by physical testing on a scaled-down model turbine and primarily numerical simulations. Numerical investigations of a proposed full-scale turbine(power coefficient, blade loads and flow behaviour) were undertaken using the developed computational models. The turbine design was studied using a time-accurate Reynolds-averaged Navier–Stokes (RANS) commercial solver. A transient-rotor-stator model with a moving mesh technique was used to capture the change in flow field at a particular time step. A shear stress-transport k-omega turbulence model was used to model turbulent features of the flow. The numerical results show good agreement with experimental measurements and the theoretical double-multiple-streamtube model. Turbine sensitivity to parametric variations was also demonstrated in the full-scale numerical study. This work concludes that the developed model can effectively predict hydrodynamic performance and structural design blade loads of a vertical-axis marine current turbine.