Flow field characteristics analysis of a horizontal axis marine current turbine by large eddy simulation

Abstract

As a renewable energy, marine currents get more and more attention. Thus the development of marine current turbines is critical to the use of this energy. We use large-eddy simulation to analyse the flow field characteristics by full geometry of a horizontal axis marine current turbine. Under the effect of a discrete number of blades, blade tip vortices develop and produce velocity variation near rotor. Referring to the flow induction factors in BEM theory, this paper focuses on the study of axial and tangential velocity and it is found that the main induced velocity component by the vortices is axial velocity. According to the distribution of the two velocity components along circumferential orientation, three peak-valley values corresponding to the number of blades reflect the flow non-uniformity due to the effect of a discrete number of blades even for the upstream of rotor. Meanwhile, this effect will continue developing due to the analysis of flow characteristics in the downstream field.