NUMERICAL STUDY OF THE LATERAL BLOCKAGE EFFECT ON THE PERFORMANCE OF A NOVEL VERTICAL-AXIS TURBINE

Regarding to a novel vertical axis auto-rotation current turbine (VAACT), a detailed three-dimensional (3D) numerical study was carried out on the influence of lateral blockage on its performance using detached eddy simulation (DES) combined with the slide mesh. Firstly, time series of angular velocities during the power production stage of the turbine are given, and it is demonstrated that the increase of blockage ratio is beneficial to stabilize its rotation and power output. Also, it is found that as the lateral blockage ratio decreases, the efficiency of the turbine decreases. The fitted curve of mean power coefficient ((C-p) over bar) as a function of lateral blockage ratio is presented. Based on the fitted curve, it is roughly predicted that (C-p) over bar will be about 0.145 without the lateral blockage effect. Finally, detailed flow field characteristics such as limiting streamlines and 3D vortical structures are displayed in this paper. The two rows of side-by-side vortexes are observed to periodically fall off in the wake, and the onset vortexes behind the turbine are almost two-dimensional in the spanwise direction. All in all, this study deepens the understanding of this novel vertical-axis turbine, and can provide references for its future industrial applications.